Someone please help me with this

Answer:

LiCl = 0.492 m

Explanation:

Molal concentration is the one that indicates the moles of solute that are contained in 1kg of solvent.

Our solute is lithium chloride, LiCl.

Our solvent is distilled water.

We do not have the mass of water, but we know the volume, so we should apply density to determine mass.

Density = mass / volume

Density . volume = mass

1 g/mL . 19.7 mL = 19.7 g

We convert g to kg → 19.7 g . 1 kg / 1000g = 0.0197 kg

Let's determine the moles of LiCl

0.411 g . 1 mol / 42.394 g = 9.69×10⁻³ moles

Molal concentration (m) = 9.69×10⁻³ mol / 0.0197 kg → 0.492 m

The molal concentration of the resulting solution is 0.492 m. The concentration number of moles of solute in one kg of solvent.

It is the measure of the concentration number of moles of solute in one kg of solvent.

To calculate the molal concentration first calculated the mass of [tex]\bold {LiCl}[/tex],

[tex]\rm \ mass = density \times volume[/tex]

Put the values,

m = 1 g/mL x  19.7 mL

m = 19.7 g     or

m = 0.0197 kg

Calculate the moles of LiCl:

[tex]n =\rm \dfrac { 0.411 \ g \times 1 mol }{ 42.394 \ g }\\\\n = 9.69\times 10^{-3} \ moles[/tex]

So, now the molal concentration,

[tex]m = \rm \dfrac { 9.69\times 10^{-3}\ mol} {0.0197 \ kg} \\\\m = 0.492[/tex]

Therefore, the molal concentration of the resulting solution is 0.492 m.

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Answer:

0.127M

Explanation:

Molarity of a solution = number of moles (n) ÷ volume (V)

Molar mass of Mg(NO3)2 = 24 + (14 + 16(3)}2

= 24 + {14 + 48}2

= 24 + 124

= 148g/mol

Using the formula, mole = mass/molar mass, to convert mass of Mg(NO3)2 to mole

mole = 14g ÷ 148g/mol

mole = 0.095mol

Volume = 750mL = 750/1000 = 0.75L

Molarity = 0.095mol ÷ 0.75L

Molarity = 0.127M

Explanation:

Air is a combination of other gases, dust particles, pollens, spores etc. This means that air is a heterogeneous mixture where particles are unevenly distributed.

Air is not considered as a pure substance because there is not one element present in air. A substance which contains only one type of element is called a pure substance.

Therefore, it is wrong to use the term 'Pure Air' in Science.

Answer:

maybe it's c. An endothermic reaction

An endothermic reaction is a chemical reaction that absorbs heat. Therefore, the correct option is option C.

An endothermic reaction in thermochemistry would be any thermodynamic process that results in a rise in the system's enthalpy H (or heat capacity U). A closed system typically helps to absorb thermal energy from the surroundings during such a process, which causes heat transfer through into system.

It could be a physical process, like the melting of ice cubes, or a chemical process, like the dissolution of ammonium nitrate (NH[tex]_4[/tex]NO[tex]_3[/tex]) throughout water (H[tex]_2[/tex]O).  An endothermic reaction is a chemical reaction that absorbs heat.

Therefore, the correct option is option C.

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Answer:

.094 M

Explanation: 0.32molNaCl/ 3.4L = .094M

Answer:

turtle

Explanation:

they are slow and they take there time

Answer:

When the negatively-charged rod is brought close to the electroscope, positive charges are attracted to it and negative charges are repelled away from it. The electroscope has a net neutral charge and the rubber rod has a net negative charge. If they are brought into contact, they will both take a net negative charge.

Explanation:

I looked it up

Answer: The correct option is A) a nitrogen molecule.

Explanation:

Polar covalent molecules are defined as chemical compounds in which the difference in electronegativity between the atoms is not equal to 0. These molecules are formed by heteronuclear molecules.

Heteronuclear molecules are defined as the molecules which are formed by the combination of more than one type of atom having a different nucleus.

Non-polar covalent molecules are defined as chemical compounds in which the difference in electronegativity between the atoms is equal to 0. These molecules are formed by homonuclear molecules.

Homonuclear molecules are defined as the molecules which are formed by the combination of one type of atom having the same nucleus.

From the given options:

It is a homonuclear molecule formed by the combination of 2 nitrogen atoms

It is a heteronuclear molecule formed by the combination of 1 nitrogen and 1 oxygen atoms

It is a heteronuclear molecule formed by the combination of 2 nitrogen and 1 oxygen atom and has some dipole moment. Thus, is considered a polar molecule

It is a heteronuclear molecule formed by the combination of 1 nitrogen and 2 oxygen atoms and has some dipole moment. Thus, is considered a polar molecule

Hence, the correct option is A) a nitrogen molecule.

Answer:

B - The high temperature makes the gas molecules spread apart according to Charles's law because this law describes how a gas will behave at constant pressure.

Explanation:

Charle's Law describes the relationship between temperature and volume, where increased temperature leads to increased volume. When volume is increased, that means the gas molecules are more spread apart and have more random motion. Therefore, the answer is B.

The high temperature causes the gas molecules to spread apart according to Charles's law because explain how a gas, behave at constant pressure.

The physical principle called Charles' law which  states that the volume of a gas equals a constant value many by its temperature as measured on the Kelvin scale.

Volume regaled by a clinched amount of gas is directly proportional to its temperature and pressure if remains steady.

Thus, option "B" is correct, the volume of a gas equals a constant value.

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Answer:

Reactions in which a multiple bond between two atoms becomes partly or fully saturated by covalent attachments... A typical addition reaction may be illustrated by the hydrochlorination of propene (an alkene), for which the equation is CH3CH = CH2 + HCl → CH3C+HCH3 + Cl− → CH3CHClCH3.

Explanation:

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CH3CH = CH2 + HCl → CH3C+HCH3 + Cl− → CH3CHClCH3.

This reaction is the example of addition reaction.

An addition reaction is defined as a chemical reaction in which two or more molecules combine to produce a bigger molecule. This type of reaction is called addition reaction.

So we can conclude that the formation of bigger molecule is the example of addition reaction.

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Answer:

(b) Chlorine takes electrons from potassium in the reaction.

Explanation:

Oxidation-Reduction: A reaction in which electrons are exchanged from one substance to another, also called redox.

In K(s) + Cl2(g) → 2KCl(s) , the electrons are being exchanged between one another. In this case, Chlorine atoms are taking electrons from potassium.

you're welcome

The reaction has been termed the oxidation-reduction reaction, as Chlorine takes electrons from potassium. Thus, option C is correct.

The reaction between Chlorine and Potassium has resulted in the formation of Potassium Chloride. The reaction has been termed the ionic redox reaction.

The redox reaction can be described as the oxidation-reduction reaction in which the oxidation of an atom by the loss of electrons, results in the reduction of another atom by the gain of the electron.

In the reaction of Chlorine and Potassium, there has been the loss of electron potassium and the gain of electrons by Chlorine. Thereby Potassium is getting oxidized, and Chlorine is getting reduced.

Thus, the reaction has been termed the oxidation-reduction reaction, as Chlorine takes electrons from potassium. Thus, option C is correct.

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Answer:

5Atm

Explanation:

I just guess and it’s right

Answer:

The milk takes shape of the round glass.

Answer:

0.00370 g

Explanation:

From the given information:

To determine the amount of acid remaining using the formula:[tex]\dfrac{(final \ mass \ of \ solute)_{water}}{(initial \ mass \ of \ solute )_{water}} = (\dfrac{v_2}{v_1+v_2\times k_d})^n[/tex]

where;

v_1 = volume of organic solvent = 20-mL

n = numbers of extractions = 4

v_2 = actual volume of water = 100-mL

k_d = distribution coefficient = 10

∴

[tex]\dfrac{(final \ mass \ of \ solute)_{water}}{0.30 \ g} = (\dfrac{100 \ ml}{100 \ ml +20 \ ml \times 10})^4[/tex]

[tex]\dfrac{(final \ mass \ of \ solute)_{water}}{0.30 \ g} = (\dfrac{100 \ ml}{100 \ ml +200 \ ml})^4[/tex]

[tex]\dfrac{(final \ mass \ of \ solute)_{water}}{0.30 \ g} = (\dfrac{1}{3})^4[/tex]

[tex]\dfrac{(final \ mass \ of \ solute)_{water}}{0.30 \ g} = 0.012345[/tex]

Thus, the final amount of acid left in the water = 0.012345 * 0.30

= 0.00370 g

Answer:

2266g

Explanation:

mass = no.of molecules /6.o23*1o(23) * molar mass

molar mass of co2= 44g /mol

1.5 .10^25/6.023 .10^23 =51.5 moles of co2

51.5 .44g/mol =2266 g

1 mole is equal to 6.023 × 10 ²³ molecules. 2266 grams are in 1.50 x 10²⁴ atoms of copper.

The term mole is defined as the amount of substance of a system which contains as many elementary entities.

One mole of any substance is equal to 6.023 × 10²³ units of that substance such as atoms, molecules, or ions. The number 6.023 × 10²³ is called as Avogadro's number or Avogadro's constant.

The mole concept can be used to convert between mass and number of particles.

mass = number of molecules / 6.023 × 10²³ × molar mass

molar mass of CO2 = 44g /mol

1.5 .10^25 / 6.023 × 10^23

= 51.5 moles of CO2

= 51.5 .44g/mol

= 2266 g

Thus, 2266 grams are in 1.50 x 10²⁴ atoms of copper.

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Answer:

P = pressure T = temperature

Answer:

Explanation:

fluorine have gained one electron that is why the sign is -1. they both have different number of protons. They have different neutron numbers. F have 10 and O have 8.

hope this helps :)

Answer:

sending heat waves and vibrations

Answer:

46 pounds

Explanation:

Let the amount of Plutonium-238 left after 10 years be P

Let the initial mass of Plutonium-238 be Po

Let the rate of decay be r

Let the time taken be t

Hence;

P = Poe^-rt

P= 50e^-0.008×10

P= 46 pounds

Answer:

The equation: (NH₄)₂SO₄ = 2NH4(+) + SO4(-2)

The number of moles = 5 g / 132.14 g/mol = 0.038 mol

The number of molecules = 0.038 X 6.022x10^23 = 2.29x10^23

the number of positive ions present in the ammonium sulphate solution:

2 positive ions for every 1 molecule of (NH₄)₂SO₄

so 2 x 2.29x10^23 = 4.58x10^23

the number of negative ions present in the ammonium sulphate solution

1 negative ion for every 1 molecule of (NH₄)₂SO₄

so 1 x 2.29x10^23 = 2.29x10^23

the total number of ions present in the ammonium sulphate solution​

4.58x10^23 + 2.29x10^23 = 6.87x10^23

Explanation:

Do đó cấu hình electron của canxi là: 1s2 2s2 2p6 3s2 3p6 4s2.

Fluids are liquid and gases. They take the shape of their containers. They are called fluids because of their ability to flow.

Answer:

70.137 °C

Explanation:

The reaction generated from the question can be expressed as:

[tex]2NaOH_{(s)} + H_2SO_{4(aq)} \to Na_2SO_{4(aq)} +2H_2O_{(l)}[/tex]

The enthalpy reaction:

[tex]\Delta H^0 _{rxn} = \sum \Delta H^0 _{f (products)} - \sum \Delta H^0 _{f (reactants)}[/tex]

[tex]\Delta H^0 _{rxn} =[2 \times \Delta H^0 _f (H_2O) + \Delta H^0 _f (Na_2SO_4) ] -[2 \Delta \times H^0 _f (NaOH) + \Delta H^0 _f (H_2SO_4) ][/tex]

Repacing the values of each compound at standard enthalpy conditions;

[tex]\Delta H^0 _{rxn} =[2 \times -279.4 + (-1384.49)]-[(2\times -418) -913]\ kJ[/tex]

[tex]\Delta H^0 _{rxn} =-194.29 \ kJ[/tex]

no of moles of NaOH = 12.618g/39.99 g/mol

= 0.3155 mol

no of moles of H₂SO₄ = molarity of H₂SO₄ × Volume

= 1.3553 mol/L × 100 × 10⁻³ L

= 0.13553 mol

From the reaction,

1 mol of NaOH = 2 × mol of H₂SO₄

Since mol of NaOH is greater than that of  H₂SO₄, then NaOH is the excess reagent and H₂SO₄ is the limiting reactant

∴

1 mol of H₂SO₄ yields = - 194.29 kJ

0.13553 mol of H₂SO₄ will yield;

[tex]= \dfrac{-194.29 \ kJ}{1 \ mol} \times 0.13553 \ mol[/tex]

= -26.332124 kJ

= -26332.12 J

Finally,

Heat(q) = [tex]m_{(copper)} \times C_{(copper)}\times \Delta T[/tex]

26332.12 J = 1.317 × 10³ g × 0.375 J/g°C ×ΔT

26332.12 J = 493.875 J/° C  × ΔT

26332.12 /  493.875 = ΔT

ΔT = 53.317 °C

[tex]T_f - T_i = 53.317 ^0 C[/tex]

[tex]T_f[/tex]- 16.82 °C = 53.317 °C

[tex]T_f[/tex] = (53.317 + 16.82) °C

[tex]T_f[/tex] = 70.137 °C

Answer: The amount of heat needed to melt the given amount of octane is 84.6 kJ

Explanation:

We know:

Boiling point of Octane = [tex]125.6^oC[/tex]

Few processes involved are:

(1): [tex]C_8H_{18} (s) (-57^oC, 219K) \rightleftharpoons C_8H_{18}(s) (-57^oC, 219K[/tex]

(2): [tex]C_8H_{18}(l) (-57^oC, 219K) \rightleftharpoons C_8H_{18}(l) (99.2^oC,372.2K)[/tex]

Calculating the heat absorbed for the process having same temperature:

[tex]q=n\times \Delta H_{(f)}[/tex] ......(i)

where,

q is the amount of heat absorbed, n is the moles of sample and [tex]\Delta H_{(f)}[/tex] is the enthalpy of fusion

Calculating the heat released for the process having different temperature:

[tex]q=n\times C_{l}\times (T_2-T_1)[/tex] ......(ii)

where,

n = moles of sample

[tex]C_{l}[/tex] = specific heat of liquid

[tex]T_2\text{ and }T_1[/tex] are final and initial temperatures respectively

The number of moles is defined as the ratio of the mass of a substance to its molar mass.

The equation used is:

[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex] ......(3)

Given mass of octane = 160. g

Molar mass of octane = 114.23 g/mol

Plugging values in equation 3:

[tex]\text{Moles of octane }=\frac{160.g}{114.23g/mol}=1.40 mol[/tex]

We are given:

[tex]n=1.40mol\\\Delta H_{fusion}=20.740 kJ/mol[/tex]

Putting values in equation (i), we get:

[tex]q_1=1.40mol\times 20.470kJ/mol\\\\q_1=28.658kJ[/tex]

We are given:

[tex]n=1.40mol\\C=255.68J/mol^oC\\T_2=99.2^oC\\T_1=-57^oC[/tex]

Putting values in equation (ii), we get:

[tex]q_2=1.40mol\times 255.68J/mol^oC\times (99.2-(-57))\\\\q_2=55912.10J=55.912kJ[/tex]

Calculating the total amount of heat released:

[tex]Q=q_1+q_2[/tex]

[tex]Q=[(28.658)+(55.912)]kJ=84.6kJ[/tex]

Hence, the amount of heat needed to melt the given amount of octane is 84.6 kJ

Answer:

h2o2 and liver produce oxygen gas

Answer:

pOH = 0.3

Explanation:

As KOH is a strong base, the molar concentration of OH⁻ is equal to the molar concentration of the solution. That means that in this case:

With that information in mind we can calculate the pOH by using the following formula:

Answer:

Constitutional Isomers

Explanation:

Constitutional isomers can be regarded as structural isomers ,these are compounds that have the same molecular formula with different structural formulas. Example is Butane and isobutane; both compound posses the same molecular formula(C4H10) with different structural formulas. compounds of Constitutional isomers are differ in term of connectivity, which

is the way the constituent atoms are been connected to another. It should be noted that Constitutional Isomers Share the same molecular formula but have different connectivity of atoms and different physical properties.

Answer:

0.515 M

Explanation:

The reaction that takes place is:

First we convert 1.22 g of malonic acid into moles, using its molar mass:

Then we convert 0.01172 malonic acid moles into NaOH moles, using the stoichiometric coefficients of the balanced reaction:

Finally we calculate the concentration of the NaOH solution, using the number of moles and given volume:

Converting 45.5 mL ⇒ 45.5/1000 = 0.0455 L

Answer:

35.75 days

Explanation:

From the given information:

For first-order kinetics, the rate law can be expressed as:

[tex]\mathsf{In \dfrac{C}{C_o} = -kt}[/tex]

Given that:

the rate degradation constant = 0.12 / day

current concentration C = 0.05 mg/L

initial concentration C₀ = 3.65 mg/L

[tex]\mathsf{In( \dfrac{0.05}{3.65})= -(0.12) t}[/tex]

㏑(0.01369863014) = -(0.12) t

-4.29 = -(0.12)

t = -4.29/-0.12

t = 35.75 days