A student is told that both energy and mass must be conserved in every chemical reaction. She measures the mass of Hydrochloric acid and a zinc strip separately. She then places the zinc strip into the acid and bubbles form as the zinc looks like it disappears. The combined mass afterward is less than the original.

Which of these can explain this result?

Answers

Answer 1

The bubbles indicate that a gas is created and mass is lost as it escapes from the container.

Why stduent is told that the both energy and the mass must be conserved in every chemical reaction?

According to the the law of conservation of mass states that in a chemical reaction mass is neither created nor destroyed.So that the student told that both the energy and mass must be conserved in every chemical reaction.

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Related Questions

In a titration, acetic acid is used as the analyte and sodium hydroxide is the titrant. At the equivalence point, will the ph be higher than, lower than, or equal to 7?.

Answers

In a titration, acetic acid is used as the analyte and sodium hydroxide is used as the titrant. At the equivalence point,  ph be higher than 7.

The equivalence point of the titration is that point at which enough titrant has been added to react with all of the substance being titrated. A strong acid with a weak base gives a slightly acidic salt. Likewise, a strong base with weak acid gives slightly basic salt.

When acetic acid react with NaOH then a salt sodium acetate and water is formed. Acetic acid, CH3COOH react with sodium hydroxide, to produce sodium acetate, CH3COONa and water

CH3COO- + H2O ---> CH3COOH + OH-

This reaction of the acetate ion makes the ph greater than 7.

At the equivalence point, moles of acetic acid is equal to the moles of sodium hydroxide. The solution will turn pink as more of sodium hydroxide is added.

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.. / -.-. .- -. / .--. .- -.-- / - .... .-. ..- / .--. .- -.-- .--. .- .-.. --..-- / .--- ..- ... - / -.. .-. --- .--. / .. - / .- ..-. - . .-. / ..- / .- -. ... .-- . .-.
1.) Answer the following:

2NH3(g)+ 5F2(g) =N2F4(g) +6HF(g)

Calculate

a. the stoichiometric ratio of moles NH3 to moles F2

b. the actual NH3 to F2 mole ratio when 0.235 mol NH3 is mixed with 0.368 mol F2

c. the limiting reactant (NH3 to F2) for the mixture in (b)

d. the theoretical yield, in moles, of N2F4 for the mixture in (b)


2.) Use the given equation to solve the problems

3Fe(g) + 4H2O = Fe3O4 (g) +4H2 (g)

a. How many moles of Fe would be required to react with 2.0 mol of H20?

b. How many moles of Fe3O4 can be produced from 6.0 mol of Fe?

c. How many grams of Fe3O4, can be produced from 10.00 g of Fe?

d. If you have 10.00g of Fe, how many grams of H2O will be needed for a complete reaction?

e. When 50.00g of Fe is reacted with excess H2O, 57.89 g of Fe3O4 is produced. What is the percentage yield of Fe3O4?


Thank you very much.

Answers

The precise proportion of air to a combustible gas or vapor at which complete combustion occurs is known as the stoichiometric ratio.

To determine the stoichiometry by mass, multiply the quantity of molecules needed for each reactant by its molar mass to get the mass of each reactant per mole of reaction. Divide each by the sum of the reactions to determine the mass ratios.

In the field of chemistry known as stoichiometry, needed quantitative data is ascertained by exploiting relationships between the reactants and/or products of a chemical process. Stoichiometry literally translates as the measure of elements because the Greek words stoikhein and metron both mean element and measure, respectively.

2NH3 (gas) + 5F2 → N2F4 + 6HF

    34g          190g     104g

Quantity of N2F4​ created from 2gNH3 = (104/34) × 2 = 6.12

Quantity of N2F4​ created from 8gF2 = (104​/109) × 8 = 4.38

N2​F4 ​will be limited, and the real product weight is 3.56 g.

Yield % = (Actual product quantity / calculated product quantity) x 100

             = (3.56 / 4.83) x 100

             = 81.28%

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whats the molarity of phosphoric acid in a solution labelled 20% of Phosphoric acid by weight and a density of 1.12g/mL

Answers

The molarity of phosphoric acid in a solution labelled 20% of Phosphoric acid by weight and a density of 1.12g/mL is 11.85 mol/L.

What is molarity?

The number of moles of solute divided by the number of liters of solution is the definition of molarity, a concentration unit in chemistry. Molarity is measured in moles per liter (mol/L).

Number of moles of phosphoric acid whose molar mass is 98:

[tex]Number of moles = \frac{mass}{molar mass}[/tex]

n = 20/98

n = 0.204 mols

[tex]Volume = \frac{mass}{density }[/tex]

V = 20/1.22

V = 17.85 ml

Molarity is the number of moles of solute per liter of solution.

[tex]M = \frac{n}{V}[/tex]

Where, M = molarity, V = volume of solvent in liters, n = no. of moles of solute.

So, [tex]M = \frac{0.204}{17.85} \times \frac{1000}{1}[/tex]

M = 11.85 mol/L

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Determine the empirical and molecular formulas for a compound that gives the following percentages on analysis (in mass percent):
71.65% Cl 24.27% C 4.07% H
The molar mass is known to be 98.96 g/mol

Answers

The empirical and molecular formula of a compound that has the aforementioned percentages are CClH₂ and C₂Cl₂H₄ respectively.

How to calculate empirical formula?

The empirical formula, which is a notation indicating the ratios of the various elements present in a compound, without regard to the actual numbers, can be calculated as follows:

71.65% Cl = 71.65g ÷ 35.5 = 2.02mol24.27% C = 24.27g ÷ 12 = 2.0223mol4.07% H = 4.07g ÷ 1 = 4.07mol

Next, we divide by the smallest mole value as follows:

Cl = 2.02mol ÷ 2.02 = 1C = 2.0223mol ÷ 2.02 = 1H = 4.07mol ÷ 2.02 = 2

The empirical ratio of Cl:C:H is 1:1:2, hence, the empirical formula is CClH₂.

The molecular formula can be calculated as follows:

{CClH₂}n = 98.96g/mol

(12 + 35.5 + 2)n = 98.96

49.5n = 98.96

n = 2

The molecular formula of the compound is C₂Cl₂H₄

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The empirical and molecular formula for the compound is CClH₂ and C₂Cl₂H₄ respectively.

What is empirical formula?

Empirical formula is defined as a chemical formula where the number of atoms in the molecule is replaced by the most basic ratio of the elements in the compound.

Molecular formula is defined as a chemical formula that specifies how many atoms of each element there are in total in each substance's molecules.

Without respect to actual quantities, the empirical formula, which is a notation representing the ratios of the different elements contained in a compound, can be determined as follows:

71.65% Cl = 71.65g ÷ 35.5 = 2.02mol

24.27% C = 24.27g ÷ 12 = 2.0223mol

4.07% H = 4.07g ÷ 1 = 4.07mol

The smallest mole value is

Cl = 2.02mol ÷ 2.02 = 1

C = 2.0223mol ÷ 2.02 = 1

H = 4.07mol ÷ 2.02 = 2

So the empirical formula is CClH₂

The molecular formula can be calculated as

[CClH₂]n = 98.96g/mole

(12 + 35.5 + 2)n = 98.96

49.5n = 98.96

n = 2

So, the molecular formula is C₂Cl₂H₄

Thus, the empirical and molecular formula for the compound is CClH₂ and C₂Cl₂H₄ respectively.

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Which group's results are unexpected and what mistake did they most likely make?

Group A is incorrect and they most likely added too much acid.

Group A is incorrect and they most likely added too little acid.

Group B is incorrect and they most likely added too little acid.

Group B is incorrect and they most likely added too much acid.

Answers

Group B is incorrect and they most likely added too much acid. Option D.

Group B Streptococci Group B Streptococci GBS are bacteria that naturally occur and migrate in the body. Although most of the time the bacteria are not harmful, they can cause serious illness in people of all ages. In fact group, B streptococcal disease is a common cause of serious infections in newborns. A positive test result means you have a group B streptococcal infection.

This doesn't mean you will get sick or affect your baby, but it does mean that you are at a higher risk of passing the bacteria on to your baby. Group B Streptococcus also known as Group B Streptococcus GBS is a type of bacterial infection found in the vagina or rectum of pregnant women. This bacterium is normally found in the vagina and/or rectum of about 25% of healthy adult women. GBS-positive females are considered colonized.

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The answer key says its D). Why isn't the answer B)
Wouldn't the equation be an endothermic forward reaction so decreasing the temp would shift the equilibrium to the left?

Answers

We can see that the reaction is endothermic hence it would be shifted to the left by;

1) Decreasing the concentration of ammonia

2) Increasing the pressure of the system

What is the equilibrium?

We know that the position of the equilibrium could be affected when the parameters of the reaction are altered. Thus we often say in chemistry that when a constraint is imposed on a system that has already attained equilibrium, then the system must have undergo a through readjustment of itself so that it could be able to annul the constraint.

Let us note that that we want the equilibrium position to move to the left in this case and have more products.

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abs plastic is a polymer consisting of three monomer units: acrylonitrile (c₃h₃n), butadiene (c₄h₆), and styrene (c₈h₈). a sample of abs plastic contains 14.9% n by mass. it took 1.56 g of br₂ to react completely with a 2.00 g sample of abs plastic. bromine reacts 1:1 (by moles) with the butadiene units in the polymer and nothing else, so bromination is a method for determining the quantity of butadiene in the polymer. what is the percent by mass of styrene in the polymer?

Answers

The ABS plastic is a polymer which has styrene 28.5% by mass.

A polymer is a substance or material made up of macromolecules, which are very big molecules made up of several repeating subunits.

Styrene and acrylonitrile are polymerized with polybutadiene to create ABS, a terpolymer. Since ABS plastic is amorphous, it lacks a proper melting point.

A polymer called a terpolymer is created when three distinct monomers are copolymerized.

Let the mass of sample ABS plastic = 100 g

Given, mass of Nitrogen (N) in ABS plastic = 11.9 g

Moles of Nitrogen (N) in ABS plastic = 11.9 / 14 = 0.85 mol

1 mole of N is present in 1 mole of acrylonitrile

0.85 mol of N is present in acrylonitrile = 0.85 mol

Moles of acrylonitrile = 0.85 mol

Mass of acrylonitrile = 0.85 mol X 53 g/mol = 45.05 g

Moles of [tex]Br_2[/tex] reacted = 1.56 g / 159.8 g/mol = 0.0098 mol

As given, [tex]Br_2[/tex] and butadiene react in 1:1 by moles

So, moles of butadiene = 0.0098 mol

Mass of butadiene in 2g ABS sample = 0.0098 mol X 54 g/mol = 0.529 g

Mass of butadiene in 100g ABS sample= 0.529 / 2 x 100 g = 26.45 g

Mass of styrene in 100g ABS Sample = mass of sample - mass of butadiene - mass of acrylonitrile

Mass of styrene = 100 – 26.45 – 45.05 = 28.5g

% Mass of styrene = 28.5%

Result:

28.5% of styrene is present in 100g ABS plastic, which is a polymer.

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how are the groups named in IUPAC(1984) and Bohr(1920) schemes . ​

Answers

The IUPAC terminology is based on the longest chain of carbons connected by a single bond, whether it be a continuous chain or a ring.

All deviations, whether multiple bonds or atoms other than carbon and hydrogen, are identified by prefixes or suffixes in accordance with a particular set of priorities.

A functional group's naming IUPAC

To assist you in identifying the compound, the carbon atoms have been given numbers.

Identifying the functional group.the longest carbon chain to be found.The longest chain of carbon atoms should be counted.Find any branching groups, identify them, and state where they are located along the carbon chain.Consolidate the name's components into a single word.

An organic compound's systematic IUPAC name has four components.

Root phraseSuffix(es)Infix(es) Prefix(es).

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let's consider that ethyl acetate is the ideal solvent for this tlc experiment. what might have happened to the spots if you had used acetone as the eluent instead of ethyl acetate.

Answers

Silica gel is polar, sure. If three doors are present at this time and you look at the TNC played here, this door is performing the less polar structure. And the more polar one is displayed here.

The first question in this query asks us about silica gel's polar properties. Silica gel is therefore polar, yes. If three doors are present and the TNC is being played here, this door is performing the least polar structure.

And the more polar one is displayed here. The tile accidents' structure, I believe, is what comes next. As a result, the tile acetate has the following structure. He did it in a similar manner. And the magazine's structure is as follows.

This is a magazine, then. Nixon is made up of 12345 and six carbon atoms. This has six carbons in it.

In response to the second question, 75% of respondents indicated that they would be highly hesitant to give Zane a hug. The answer is 75/25". Since there is a greater amount of polar solvent, it will hesitate, and the magazine is a non-polar solvent.

Therefore, the new solvent is more dated than Poehler's new solvent. R. F values for sports rise as solvent concentration rises. Therefore, as the polarity of the solvent grows, our F values, office boards, and material become more connected to the solvent and move with it. Thus, all winter sports are faster in pollers. These sports have quicker paces.

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27. Sample of gas is electrically charged so that it glows red. The red color is emitted when

Answers

The red color is emitted when electrons in the gas return to ground state.

What is the Bohr model?

From the Bohr model, we know that an electron in atom could be found in its lowest energy state. The electron could receive energy in this lowest energy state and move to a higher energy state called the excited sate. The lower energy state that the electron was at the first is called the ground state of the electron.

As the electrons return to ground states, photons of light of a characteristic wavelength is emitted. The color of the light shows the wavelength of the light emitted.

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At the end of the video, the man getting interviewed provides an analogy about meditation and states of matter. Create your own analogy that explains the differences between the behavior of molecules in different states of matter. Explain.

Answers

Marathon runners well exhibit the differences between the behavior of molecules in different states of matter.

At the starting point before the start of the race, the runners would gather in a common place before the starting line. They would be close to each other and are tightly packed like solid molecules.

After the race was started, some players would start to move fast and some remain in a group for a certain period. They were loosely packed compared to solid.

As the game reaches the end point, the players would be more spread out based on their stamina. They would be more loosely packed compared to solid and liquid.

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(a) what fraction of the neutron's kinetic energy is transferred to the carbon nucleus? (the mass of the carbon nucleus is about 12.0 times the mass of the neutron.)

Answers

There is the neutron's total kinetic energy. E is the same as the final kinetic energy of the EF-2 carbon nucleus. Okay, I'm down one from k E F one. In other words, Jews, this is 1.3 incremental -13 -4, -3.69 into 10 to the Power -14. 1.3 into a power of 10 to the -13th Minour.

Two will equal twelve in one if we subscribe one river to the neutron and another to carbon. Okay. EI one, which is a brand-new drone's first kind of technology, is equivalent to one three into ten to thirteen. For the first support, no. Half of Mnu square is equal to E I and E F, respectively, as well as one V squared. Additionally, if you apply the law of conservation of momentum, M 1 - M 2 will equal 1 + M 2 into Vi, giving you v = 2 and M 1 - M 2. And to you, multiplied by M1 + M2, is mmhmm.

As a result, if you substitute, the answer to the second equation will be K E F 1, which is equal to half of M 1, which is divided by M 1 plus M 2 entire square to give you square. We make this much simpler. And if we divide KEF one by KEI one, we get four, which is equal to M1 plus M2 divided by M1. Cool square, can you divide 4 M1 12 by M 1 + 12? My father has all this. One divided by M. They were by 1 69, which is equal to 40.

This serves as the first support's response. The final kinetic energy is provided by k e F one as a result of the neutron's current technology being transmitted to carbon during the collision's second support. That is equivalent to 3.69 into 10 and 48 x 1, respectively, and to 1.3 into 10 to the power of 13 and 69. Jews, to the Power -14. There is the neutron's total kinetic energy. E is the same as the final kinetic energy of the EF-2 carbon nucleus. Okay, I'm down one from k E F one. In other words, Jews, this is 1.3 incremental -13 -4, -3.69 into 10 to the Power -14. 1.3 into 10 to the power -13 Minor of the original solution.

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what temperature will the water reach when 10.1 g cao is dropped into a coffee cup containing 157 g h2o at 18.0°c if the following reaction occurs? cao(s) h2o(l) → ca(oh)2(s) δh°rxn

Answers

By using the specific heat capacity of water, the temperature of the water in the cup is found to reach 38.5℃ assuming the cup absorbs negligible heat as it is a perfect insulator.

The specific heat capacity of a substance is defined as the amount of heat (J) absorbed per unit mass (kg) when its temperature rises 1 K (or 1 °C).

The specific heat capacity of a solid is determined by its mass, temperature change, and solid nature.

Specific heat capacity is useful in calculating processing temperatures and the amount of heat required for processing, as well as in distinguishing between two polymeric composite materials.

No. of moles of CaO available = 10.1 / 56 = 0.18 mol

Since 1 mol reactant supplies 64.8 kJ, thus 0.18 mol gives = 11.69 kJ

Therefore, we have 11.69 kJ heat available

Now,

ΔH = mCΔT

where,

ΔH = heat supplied

C = specific heat

ΔT = rise in temperature

Therefore,

ΔT = ΔH/mC = 17.8

Thus,

Final temperature = 18 + 17.8 = 35.8℃

Result:

Hence, (B) 35.8℃ is the temperature of the water in the cup.

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Human Hair Predicts Weathery
Bad hair days are not new to science! In 1783, Swiss geologist Horace Benedict de
Saussure observed that strands of hair lengthen or contract when exposed to
different levels of moisture. He used this knowledge to invent a device that used
human hair to measure the amount of moisture in the atmosphere.
The hair hygrometer was just one tool used to measure changes in the atmosphere.
Can you think of any others? With a partner, brainstorm a list of techniques or tools
that are used to record weather. Write your ideas in the space below.

Answers

A list of techniques or tools that are used to record weather are:

Doppler radarAnemometersWind vanesBarometersSatellite dataRadiosondesLightning detectors.

What are the techniques of recording data about?

The meteorologist's window into witnessing powerful storms is Doppler radar. It uses 159 radar towers spread out over the country to find all kinds of precipitation, the rotation of thunderstorm clouds, tornado debris in the air, and wind speed and direction.

Temperature is measured via thermometers. Humidity is measured via hygrometers. The quantity of water vapor in the air is known as humidity.

From space, weather satellites keep an eye on Earth and collect observational data that our scientists study. Geostationary satellites orbit the Earth at a fixed altitude, taking pictures of the entire planet as regularly as every 30 seconds.

Lastly, The upper stratosphere is where radiosondes float, where they gather and transmit information about air pressure, temperature, relative humidity, wind speed, and wind direction every second.

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i will give 100 points for help

Answers

Answer: Hope this helps!

Explanation:

Oxygen has the atomic number 8; its atoms contain 8 protons and 8 electrons. Uranium has the atomic number 92; its atoms contain 92 protons and 92 electrons.

I don't know if this is what your looking for but i think it should help!

problem 3 how many rearrangements of are there in which no two adjacent letters are also adjacent letters in the alphabet? for example, no such rearrangements could include either or .

Answers

There are 2 rearrangements of abcd in which no two adjacent letters are also adjacent letters in the alphabets.

Here's the Complete question:

How many rearrangements of abcd are there in which no two adjacent letters are also adjacent letters in the alphabet? For example, no such rearrangements could include either ab or ba.

(A) 0

(B) 1

(C) 2

(D) 3

(E) 4

Using XXXX

We can't put B in either of the middle positions, as there would only be the far end at which to put both A and C and we can't put two things in one slot. That is, XBXX would require A and C to both be in the red X in order to avoid putting them next to B...can't do that, so B can't go in the middle.

Similarly, we can't put C in either of the middle positions, as there would only be the far end at which to put both B and D and we can't put two things in one slot.

So, B and C must go on the ends.

BXXC can only be filled in as BDAC.

CXXB can only be filled in as CADB.

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The hydrochloric acid utilized in this experiment can often discolor gloves if it is spilled on them during use. If this does occur, what should be done in order to remedy this potentially hazardous situation?.

Answers

There are many applications for hydrochloric acid. It is used for the production of chlorides, fertilizers and dyes, as well as in galvanic plating and in the photographic, textile and rubber industries.

Eyes, skin and mucous membranes are corroded by hydrochloric acid. In humans, acute (short-term) inhalation exposure may cause eye, nose, and respiratory tract irritation, as well as inflammation and pulmonary edema. Acute oral exposure can cause mucosal, esophageal, and stomach burns, and dermal contact can cause severe burns, ulceration, and scarring in humans. Gastritis, chronic bronchitis, dermatitis, and photosensitization have all been associated with chronic (long-term) exposure to hydrochloric acid. Long-term exposure to low concentrations can also cause tooth discoloration and erosion. Hydrochloric acid has not been classified as a carcinogen by the EPA.

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a 0.755g sample of hydrated copper (ii) sulfate, cuso4 x h2o was heated carefully until it had changed completely to anhydrous copper (ii) sulfate, cuso4, with a mass of 0.483 g. determine the value of x.

Answers

The value of x is 5.

We know that,

Molar mass of CuSO​​​4 = 156.609g/mol

Molar mass of H2O = 18.015g/mol

So ,Molar mass of CuSO​​​4 .xH2O = molar mass of CuSO​​​4 +X(molar mass of H2O)

Molar mass of CuSO4.xH2O=[( 156.609) + (18.015)X] g/mol 

mass of CuSO4.xH2O = 0.755gmass of CuSO​​​4 = 0.483g

And if we change 4.895 to a whole number or one significant figure,

then we get 

x = 5 

chemical formula is = CuSO4.5H2O (Blue Vitriol)

What is molar mass?
The molar mass of a chemical compound is determined by dividing its mass by the quantity of that compound, expressed as the number of moles in the sample, measured in moles.

Therefore the value of x is 5.

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7. Explain how excitatory and inhibitory actions of neurotransmitters are different.

Answers

In contrast to an inhibitory transmitter, an excitatory transmitter encourages the development of an electrical signal known as an action potential in the receiving neuron.

Depolarization is brought on by excitatory neurotransmitters (decrease in membrane potential). Hyperpolarization is brought on by inhibitory neurotransmitters (increase in membrane potential).

Neurotransmitters fall into two categories: excitatory and inhibitory. While inhibitory neurotransmitters work to stop an action potential, excitatory neurotransmitters function to activate receptors on the postsynaptic membrane and enhance the effects of the action potential.

While inhibitory neurons release neurotransmitters that prevent action potential firing, excitatory neurons release neurotransmitters that cause an action potential to occur in the postsynaptic neuron.

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Examine the electron configurations of oxygen, phosphorus and gallium. According to valence bond theory, how many bonds could each of these atoms form?.

Answers

Oxygen forms two bonds and the configuration is 1s₂ 2s₂ 2p₄, Phosphorus forms three bonds and the configuration is [Ne]3s₂ 3p₃, Gallium forms four bonds and the configuration is [Ar] 3d₁₀ 4s₂ 4p₁

What is valence bond theory?This concept describes chemical bonding. An atomic bond between two atoms is formed when incompletely filled atomic orbitals overlap, according to VBT. A hybrid orbital is formed by sharing the unpaired electrons. According to Valence bond theory, a metal atom or ion can use its (n-1)d, ns, np, and nd orbitals for hybridization under the influence of ligands to generate a set of equivalent orbitals with specific geometry, such as octahedral, tetrahedral, square planar, and so on. The valence bond (VB) theory, developed in large part by the American scientists Linus Pauling and John C. Slater, explains bonding in terms of hybridised orbitals of the electron. The Lewis concept of the electron-pair bond is the foundation of VB theory.

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Which statement describes the
distribution of charge in an atom?
-A neutral nucleus is surrounded by one or
more
negatively charged electrons.
-A neutral nucleus is surrounded by one or more
positiVely charged electrons.
-A positively charged nucleus is surrounded by one
or more negatively charged electrons.
-A positively charged nucleus
is surrounded by one
or more positively charged electrons

Answers

Answer:

-A positively charged nucleus is surrounded by one

or more negatively charged electrons.

During a phase change, the temperature remains constant although heat is still being added. What is the best explanation for what the heat energy is being used to do?

A) Breaking chemical bonds to form new substances.

B) Moving the particles closer together.

C) Weakening or breaking the intermolecular forces.

D) Increasing the movement of particles.

Answers

A phase change is a physical change involves no bond making or breaking. The heat energy is used to weaken the intermolecular forces of attraction and moves the molecules apart. Thus option C and D are correct.

What is a phase change?

A phase change is the change in phase or state of the substance. For example, solid to liquid, liquid to gas conversions etc. are phase changes.

During a phase change, no chemical bond is breaked or maked but the intermolecular force of attraction holding the molecules together weakens and moves the molecules apart.

Consider the phase change of solid to liquid. The closely packed molecules in solid uses heat energy to to move apart by weakening the intermolecular force and form the liquid state.

Therefore, during a phase change, heat is used to weaken or break the intermolecular force and increasing movement of particles. Thus options C and D are correct.

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a 71.0 ml portion of a 1.50 m solution is diluted to a total volume of 258 ml. a 129 ml portion of that solution is diluted by adding 149 ml of water. what is the final concentration? assume the volumes are additive.

Answers

The final concentration assuming the volumes are additive when a 71.0 ml portion of a 1.50 m solution is diluted to a total volume of 258 ml. a 129 ml portion of that solution is diluted by adding 149 ml of water is 0.191 M

This can be solved by using the dilution factor.

So the dilution factor for the first dilution is 71.0 ml to 258 ml

DF1=258/71=3.63

For the first solution, the dilution factor is

3.163, refers that the concentration is decreased by a factor of 3.163.

The concentration of diluted solution is

c(diluted)=1.50/3.63=0.413

Now, you take a sample of 129 mL of this diluted solution and add another 165 mL of water. So,

V(final)=129ml +149 ml=278 mL

The concentration of the 129 mL sample is equal to the concentration of the first diluted solution, i.e. 0.413 M

So,

DF2=278/129=2.155

So, the final concentration is

c(final)=0.413/2.155=0.191 M

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part a a solution is prepared by dissolving 0.69 mol of mgcl2 in 0.40 kg of water. how many moles of ions are present in solution? express your answer to two significant figures and include the appropriate units. n

Answers

The moles of ions present in the solution when a solution is prepared by dissolving 0.69 mol of mgcl2 in 0.40 kg of water is 2.0 moles.

0.69 moles of MgCl2 in 0.4 kg water

MgCl2 disassociates as Mg2+ + 2Cl-

So 1 MgCl2 from 3 moles

Moles of ion present is 3x0.69=2.0 moles

The number of moles is given mass by molecular mass.Significant figures are a way of expressing numbers.In positional notation, significant figures are the digits in a number that is trustworthy and required to denote the amount of something.

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Which fundamental mechanisms appear in the reaction between pyridinium chlorochromate and a secondary alcohol? choose all that apply.

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The idea is to foretell the formation of a carbonyl compound by the reaction between alcohol and too much pyridinium chlorochromate. An oxidizing agent called pyridinium chlorochromate converts the alcohol group into the 1carbonyl group.

Carbonyl molecule

The carbonyl molecule that results from the reaction will depend on the reactant's OH group. Pyridinium chlorochromate [PCC] converts primary OH to aldehydes, whereas it converts secondary OH to ketones, and oxidation of tertiary OH has little effect. Alcohols and pyridinium chlorochromate [PCC] react to create a carbonyl molecule.

From primary alcohols to aldehydes and from secondary alcohols to ketones, pyridinium chlorochromate oxidizes alcohols one step up the oxidation ladder. pyridinium chlorochromate will not oxidize aldehydes to carboxylic acids, in contrast to chromic acid. Comparable to Pyridine (the Collins reagent) and CrO3 will both oxidize primary alcohols to aldehydes. Here are two instances of pyridinium chlorochromate being used.

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How do you expect elodea to change the ph of a solution over time when exposed to light?.

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Elodea leaves will extract CO2 from water and make glucose through photosynthesis when placed in a light environment with water. When CO2 dissolves in water, it combines with the water to produce carbonic acid (H2CO3) and acidify the water (pH 7).

What is Elodea ?

Elodea are herbaceous perennials with whorls of two to seven dark green leaves grouped along the stem. Plants often generate seeds in ellipsoid or oval capsules and are dioecious (individuals only bear one type of flower, either male or female).

Why elodea is experimental?

It is widely recommended for demonstrating oxygen formation during photosynthesis. Elodea is cheap and easy to grow. When the original pH of the water was low, Elodea had the potential to raise it, which led to more Cd accumulating in the water. The pH difference was more noticeable the more densely planted an area was. Since the pH rise was more noticeable in the absence of DCMU and in the dark, it cannot have been caused by photosynthetic activity. Cadmium was the cause of Elodea's pH increase.

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Donald rides his bicycle 12 km north, turns around, and then rides the bicycle 9 km back toward his starting point.

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Donald rides his bicycle 12 km north, turns around, and then rides the bicycle 9 km back toward his starting point.

He rides total 21 km .

What is meant by Starting point ?

An object, a concept, or a collection of data that can be utilized to start a process or conversation. The essay provided a good place to start for our conversation.

Your beginning point is the location from where you begin a journey. Safaris into northern Tanzania's game parks and reserves depart from the recently constructed airport. From their starting position, they had already traveled a few miles or more on foot.

A baseline is a beginning or the beginning of something.

The baseline line is always crucial and can be used as a basis for comparison.

In many fields, including medicine, the baseline data—which is the data discovered at the start of a study—is employed.

Every person's base line or start up is equally important and significant, and it's frequently taken seriously to avoid mistakes that might not be readily rectified.

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at the low temperatures found in some interstellar molecular clouds (around 100 k), molecular oxygen emission is strongest at a wavelength is 0.2521 cm. determine the speed (in km/s) of a low temperature molecular cloud containing molecular oxygen if its strongest emission is at a wavelength of 0.1835 cm

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By using the Doppler effect, - 81634.27km/s is found to be the velocity of the cloud.

The Doppler effect can be used to solve this problem. When an observer travels in relation to the wave source, the frequency or wavelength changes from the viewpoint of the observed. The Doppler Effect is commonly used to calculate the velocity of the origin of waves or the velocity of the viewer. The generic waveform and frequency equations are used to derive the Doppler Effect velocity equations. The source velocity may then be calculated by setting the observer velocity to zero.

The Doppler shift in wavelength or frequency is calculated using the following relationship:

Δλ / λne = ν / c

where,

Δλ = wavelength shift

λne = wavelength of stationary source

ν = velocity of source

c = velocity of light = 3 x [tex]10^5[/tex] km/s

Given:

Initial wavelength, λini = 0.2521cm

New wavelength, λnew = 0.1835cm

Calculation:

Wavelength shift,

Δλ = λnew - λini

Δλ = (0.1835cm) - (0.2521cm)

Δλ = - 0.0686

On substitution of the known values in the above equation, we get:

Δλ / λne = ν / c

- 0.0686 / 0.2521 = ν / 3 x [tex]10^5[/tex]

ν = - 0.0686 x 3 x [tex]10^5[/tex] / 0.2521

ν = - 81634.27km/s

Result:

- 81634.27km/s is found to be the required velocity of the cloud moving towards us.

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A molecule contains 3 atoms. It has 1 triple bond and 1 single bond. There are no lone pairs on any of the atoms. How many rheds are within the molecule?.

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The described molecule has 2 regions of high electron density (RHEDs). This is determined using the basics of molecule geometry and the VSEPR model.

If a molecule has three atoms, but only two bonds (1 single bond and 1 triple bond), then that molecule needs to be linear, especially because there are no lone pairs on any of the atoms. According to the VSEPR model (valence shell electron pair repulsion), each bond (it doesn't matter if it's a single, double, or triple bond) and lone pair is considered a separate region of high electron density.

Because we only have two bonds and no lone pairs, it follows that we only have two RHEDs.

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The photo shows a close-up of the surface of one of the sheets from the rock in part 1. Note the large crystals of a dark, soft, flaky mineral. What mineral is it?.

Answers

The mineral shown in the photo is Biotite as there are large crystals of a soft, dark, and flaky material.

A typical class of mica group phyllosilicate minerals is called biotite. Between the iron-endmember annite and the magnesium-endmember phlogopite, there is largely a solid-solution series; other more aluminous end-members are siderophyllite and eastonite.

Black mica called "biotite" has flawless cleavage and a vitreous sheen on the faces of the cleavage. Thin sheets of the mineral biotite are flexible but will shatter under heavy bending when separated. The sheets are transparent to translucent and appear brown, gray, or green when held up to the light.

The other mineral options are not correct because Feldspar has a white or light orange shade, Quartz is colourless and shiny, whereas Calcite is usually white or colourless.

The complete question is:

The photo shows a close-up of the surface of one of the sheets from the rock in part 1. Note the large crystals of a dark, soft, flaky mineral. What mineral is it?

a) Feldspar

b) Biotite

c) Quartz

d) Calcite

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