Answers
This question is asking for a method for the determination of the freezing point in a solution that does not have a noticeable transition in the cooling curve, which is basically based on a linear fit method.
The first step, would be to understand that when the transition is well-defined as the one on the attached file, we can just identify the temperature by just reading the value on the graph, at the time the slope has a pronounced change. For instance, on the attached, the transition occurs after about 43 seconds and the freezing point will be about 4 °C.
However, when we cannot identify a pronounced change in the slope, it will be necessary to use a linear fit method (such as minimum squares) to figure out the equation for each segmented line having a significantly different slope and then equal them so that we can numerically solve for the intercept.
As an example, imagine two of the segmented lines have the following equations after applying the linear fit method:
[tex]y=-3.5 x + 25\\\\y=-0.52 x + 2[/tex]
First of all, we equal them to find the x-value, in this case the time at which the freezing point takes place:
[tex]-3.5 x + 25=-0.52 x + 2\\\\-3.5 x+0.52 x =2-25\\\\x=\frac{-23}{-2.98}=7.72[/tex]
Next, we plug it in in any of the trendlines to obtain the freezing point as the y-value:
[tex]y=-3.5 (7.72) + 25\\\\y = 1.84[/tex]
This means the freezing point takes place after 7.72 second of cooling and is about 1.84 °C. Now you can replicate it for any not well-defined cooling curve.
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pls help me right now
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Answer:
LETTER
1. D. PURE SUBSTANCES CAN BE FURTHER BROKEN DOWN INTO SIMPLER SUBSTANCES.
2.A
PO PLEASE MARK A BRAINLIESTS ANG MARK A 5 STAR ANG HEART PO PLEASW
what does cost-effective mean? im kind of confused on cost-effective and time-effective things and i keep getting mixed up :(
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Cost-effective definition: producing good results without costing a lot of money. E.g: that machine is very cost effective, it made 200 shirts with only a dollar.
Time effective definition: how well time was used. E.g that machine is very time-effective, it made 200 pants in one hour!
Would appreciate brainly <3
Can anybody complete this for me?
Answers
Answer:
I wish i could
Explanation:
Where did the atoms come from in the first place?
Answers
Answer:
All the carbon atoms in the human body were created in the stars. Elementary particles, such as protons, were formed during the "big bang"; that amazing moment about 14 billion years ago in which the universe got it's start.
1: Given that Ka for HCOOH is 1.8×10^-4 at 25°C what is the value of b for COOH− at 25 °C?
Kb=
2: Given that b for (CH3)2 NH is 5.4×10^-4 at 25°C, what is the value of Ka for (CH3)2NH+2 at 25 °C?
Ka=
Answers
Explanation:
At 25 °C Dissociation constant of water or Kw = 1× 10^-14 mol2dm-6
Ka × Kb = Kw for all diluted solutions
Ka×Kb = 1 × 10^-14 mol2dm-6
Therefore for question 1 -
COOH- is the conjugate base for HCOOH ( we find the conjugate base by removing an H atom and the Conjugate acid by adding an H atom)
COOH- (aq) + H2O ( l) <-----> HCOOH( aq) + OH-(aq)
So we can apply the above mentioned equation to find Kb value for COOH-
Kb = 5.56 × 10^-11 moldm-3
For question 2-
We can see that (CH3)2NH+2 is the conjugate acid of (CH3)2 NH. (A H atom has been removed so the one with a H atom less is the conjugate base.)
(CH3)2NH+2 (aq) + H2O (l) <-----> (CH3)2 NH (aq) + H3O+ (aq)
So applying the previously mentioned equation we get Ka = 1.85 × 10^-11 moldm-3
2. What pressure is required to compress 196.0 L of air at 1.00 atmosphere into a cylinder
whose volume is 26 0 L? (2 points)
Answers
Answer:
7.54 atmExplanation:
The required pressure can be found by using the formula for Boyle's law which is
[tex]P_2 = \frac{P_1V_1}{V_2} \\[/tex]
where
P1 is the initial pressure
P2 is the final pressure
V1 is the initial volume
V2 is the final volume
From the question we have
[tex]P_2 = \frac{1 \times 196}{26} = \frac{196}{26} \\ = 7.538461...[/tex]
We have the final answer as
7.54 atmHope this helps you
as the solar nebula cooled which compounds were the first to condense from a gas to a solid? Rock water ice or metal
Answers
As the solar nebula cooled METAL compounds are the first to condense from a gas to a solid. The solar nebula gave birth to the Solar system.
A solar nebula is a disc-shaped cloud of gases and grain dust, which gave birth to the Sun and planets of the Solar system, approximately 4.6 billion years ago.
The solar nebula is at the beginning a mixture of interstellar gases (hydrogen and helium) and dust grains.
As the solar nebula cools, heavy elements such as metals in the disk condensate into planetesimals.
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Part C
Describe the shape of the graph showed in part B.
(Is it like- a normal shape??)
Answers
This graph shows a straight line.
Answer:
The graph is a straight line that angles upward.
Problem 07.020 - Heat transferred from cold to hot reservoir Assume that heat in the amount of 100 kJ is transferred from a cold reservoir at 600 K to a hot reservoir at 1050 K contrary to the Clausius statement of the second law. What is the total entropy change
Answers
This problem is describing a system in which 100 kJ of energy is transferred from a cold reservior at 600 K to a hot one at 1050 K. This situation is opposed to the Clausius statement of the second law of thermodynamics, because it is widely known that heat is transferred from hot to cold systems.
However, we can calculate the total entropy change by using the following formula:
[tex]\Delta S =\Delta S _{Low}+\Delta S _{High}[/tex]
Which is broken down as follows:
[tex]\Delta S =\frac{-Q}{T_{Low}} + \frac{Q}{T_{High}}\\\\\\\Delta S =Q(\frac{-1}{T_{Low}} + \frac{1}{T_{High}})[/tex]
Since the heat is assumed to be equal for the both of them. Then, we plug in the given heat and temperatures to obtain:
[tex]\Delta S =100kJ(\frac{-1}{600K} + \frac{1}{1050K})\\\\\Delta S =-0.0714\frac{kJ}{K}[/tex]
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https://brainly.com/question/17145614https://brainly.com/question/13999732After being placed on the table where should the ocular lenses face?
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Find five household items that contain ionic compounds. List the following information for each compound: a.name of the product
b. the chemical name of the ionic compound
d.the chemical formula of the ionic compound c. identify the ions present in each compound
Answers
Answer:
D . GOD BLESS .
Explanation:
What instruments are used to measure moleculars vibration , rotation and translation?
Answers
Answer:
you hear
Explanation:
beautiful hear can be wonderful day in your life so to be rotations is not a big deal
Mechanical waves travel fastest through
A -Solid
B -Liquid
C -Gas
D -Vacuum
Answers
Answer:
A-Solid
Explanation:
Waves travel faster in solids & slowest in gases
Describing Chemical Reactions
Project: Modeling the Conservation of Mass
Answers
Answer:
Step 1: Prepare for the project.
a) Read the entire Student Guide before you begin this project.
b) If anything is unclear, be sure to ask your teacher for assistance before you begin.
c) Gather the materials you will need to complete this project.
Step 2: Review the chemical reaction.
a) The chemical reaction that you will model is shown below. Calcium oxide (CaO) is a white
solid with a crystalline structure. It is made by heating limestone, coral, sea shells, or chalk,
which are composed mainly of calcium carbonate (CaCO3). During the heating process,
carbon dioxide (CO2) is released and calcium oxide (CaO) is produced. Commercially,
calcium oxide is called lime. One of the oldest uses of lime is to make mortar, a substance
used in construction to secure bricks, stones, and blocks together.
CaCO3 CaO + CO2
Step 3: Build a model of the reactant.
a) Use gumdrops and toothpicks to build a model of CaCO3.
b) Select one color of gumdrop for calcium, a second color for carbon, and a third color for
oxygen. Be sure to include a key of your chosen color scheme with your model.
c) Use the periodic table to help you determine the number of bonds each atom will form.
Step 4: Build models of the products.
a) Use gumdrops and toothpicks to build a model of CaO and a model of CO2.
b) Be sure to use the same colors of gumdrops for calcium, carbon, and oxygen as you did in
Step 3. Include a key of your chosen color scheme with your models.
c) Use the periodic table to help you determine the number of bonds each atom will form.
Step 5: Type one to two paragraphs that describe your models and explain the conservation of
mass in the chemical reaction.
a) Create a new blank document. Type your name at the top.
b) Type one to two paragraphs that describe your models and relate them to the law of
conservation of mass. Your document should:
i. identify the names of the reactants and products in the reaction.
ii. identify the number of molecules that make up the reactants and products.
iii. identify the type and number of atoms in each molecule of the reactants and products.
iv. explain what happens during the chemical reaction.
v. explain how mass is conserved during the chemical reaction.
Step 6: Evaluate your project using this checklist.
If you can check each criterion below, you are ready to submit your project.
Did you create an accurate model of calcium carbonate (CaCO3)? Your model should include
the correct number of gumdrops for each element in calcium carbonate, consistent use of
colors for elements in calcium carbonate, and the correct number and placement of toothpicks
(bonds).
Did you create an accurate model of calcium oxide (CaO)? Your model should include the
correct number of gumdrops for each element in calcium oxide, consistent use of colors for
elements in calcium oxide, and the correct number and placement of toothpicks (bonds).
Did you create an accurate model of carbon dioxide (CO2)? Your model should include the
correct number of gumdrops for each element in carbon dioxide, consistent use of colors for
elements in carbon dioxide, and the correct number and placement of toothpicks (bonds).
Did you type one to two paragraphs that describe your models and relate them to the law of
conservation of mass? Your document should include the names of the reactants and
products in the reaction, the number of molecules that make up the reactants and products,
and the type and number of atoms in each molecule of the reactants and products. It should
also explain what happens during the chemical reaction and how mass is conserved during the reaction
Step 7: Revise and submit your project.
a) If you were unable to check off all of the requirements on the checklist, go back and make
b) When you have completed your project, submit your models to your teacher for grading.
c) Submit your document through the virtual classroom. Be sure that your name is on it.
Step 8: Clean up your workspace.
a) Clean up your workspace. Return any extra materials to your teacher and throw away any trash.
Explanation:
Find the volume of 0.170 M sulfuric acid necessary to react completely with 72.2 g sodium hydroxide.
Answers
The volume of sulphuric acid, H₂SO₄ needed for the complete reaction with 72.2 g of sodium hydroxide, NaOH is 5.31 L
We'll begin by calculating the number of mole in 72.2 g of NaOH. This can be obtained as follow:
Mass of NaOH = 72.2 g
Molar mass of NaOH = 23 + 16 + 1 = 40 g/mol
Mole of NaOH =?Mole = mass / molar mass
Mole of NaOH = 72.2 / 40
Mole of NaOH = 1.805 mole Next, we shall determine the number of mole of H₂SO₄ needed to react with 1.805 mole of NaOH.2NaOH + H₂SO₄ —> Na₂SO₄ + 2H₂O
From the balanced equation above,
2 moles of NaOH reacted with 1 mole of H₂SO₄.
Therefore,
1.805 mole of NaOH will react with = 1.805 / 2 = 0.9025 mole of H₂SO₄.
Finally, we shall determine the volume of H₂SO₄.Mole of H₂SO₄ = 0.9025 mole
Molarity of H₂SO₄ = 0.170 M
Volume of H₂SO₄ =?Volume = mole / Molarity
Volume of H₂SO₄ = 0.9025 / 0.170
Volume of H₂SO₄ = 5.31 LThus, the volume of H₂SO₄ needed for the reaction is 5.31 L
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A 14.0 L container at 323 K holds a mixture of two gases with a total pressure of 8.00 atm. If there are 1.50 mol of Gas A in the mixture, how many moles of Gas B are present
Answers
The number of moles of gas B present in the gas mixture is 2.72 moles.
The given parameters;
Volume of the gases, V = 14 LTemperature of the gases, T = 323 KTotal pressure of the gases, P = 8 atmNumber of moles of gas A = 1.5 molesThe total number of moles of the gases is calculated by applying ideal gas law;
PV = nRT
where;
R is ideal gas constant = 0.0821 L.atm./mol.K
n is the total mole of the gases
[tex]n =\frac{PV}{RT} \\\\n = \frac{8 \times 14}{0.0821 \times 323} \\\\n = 4.22 \ moles[/tex]
The number of moles of gas B is calculated as follows;
[tex]n_B = 4.22 - n_A\\\\n_B = 4.22 - 1.5\\\\n_B = 2.72 \ moles[/tex]
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Identify the strongest intermolecular force that is likely to affect each of the samples described below.
A mixture of chlorine gas (Cl) and fluorine gas (F): V London dispersion forces
COMPLETE
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A mixture of hydrogen sulfide (H2S) and hydrogen chloride (HCI): V dipole-dipole interactions
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Selection
COMPLETE
Guess
this
hydrogen bonding
A mixture of water (H2O) and ammonia (NH3):
Answers
Answer:
A mixture of chlorine gas (Cl2) and fluorine gas (F2):
✔ London dispersion forces
Explanation:
What element is a gas at room temp, has 6 valence electrons, and is non-reactive
Answers
Answer:
Noble gases
Explanation:
Noble gases are nonreactive, nonmetallic elements in group 18 of the periodic table. As you can see in the periodic table in the figure below, noble gases include helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn).18 Jun 2021
which two types of food are homogeneous mixtures
A. mustard
B. mayonnaise
C. tossed salad
D. trail mix
Answers
Answer: It’s most likely Mayonnaise and mustard.
Explanation: It’s definitely mayonnaise because it’s not possible to see the different substances and for mustard it depends on what type. Hope this helps. Good luck :)
5. Select the answer for both questions
Answers
Answer:
engey
Explanation:
Bethany observes a white crystal that is cube shaped under a microscope.
Based on this observation, Bethany thinks the crystal could be sodium chloride, or table
salt. Because the crystal has an extended structure, she knows that sodium chloride is
not a molecule. Bethany uses gray and white spheres, representing the atoms in
sodium chloride, to make a model of the crystal’s most likely structure, as shown.
a. Provide two reasons why the model accurately represents sodium chloride. Support
your reasons with evidence from the model.
b. Predict whether the melting point should be high or low based on the model.
Answers
Answer:
In nature there are many different minerals we call "Salts". If you look very closely at the particles of table salt, you will find little cubic crystals. These salt crystals are made of sodium chloride (NaCl), and their cubic shape is due to a very specific arrangement of the atoms. As discussed earlier, all of the minerals classified as salts are held together through ionic bonds. The arrangement of atoms, the shapes of the crystals they form, and their mechanical, thermal, and electrical properties are all due to this special type of bonding
The two reasons why the model shows sodium chloride is that:
Sodium chloride crystals are cubic in their form as they have crystalline structure.Why sodium chloride does not exist as molecule?The other is that:
Sodium chloride does exist as an aggregates of a bigger number of ions that are oppositely charged as shown using gray and white spheres.The melting point will be high based on the model as because Sodium chloride is known to have high melting and boiling point.Note that a lot of Formula unit cannot exist as a single entity. Because of this, compound such as NaCl exist only as an aggregates of a more bigger number of ions that are oppositely charged .
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Hot air balloons are open at their lower and end. A basket is suspended from the balloon and can take several passengers as well as the pilot. A propane burner fixed to the basket is used to heat up the air in the balloon A hot balloon has a volume of 1500 m3 and its volume does not change when the enclosed air is heated.
1) Use the ideal gas equation, pV=nRT. to calculate how many molecules of the balloon contains at a temperature of 10 °C and a pressure 10.1 KP.
2) Calculate the mass of air it contains, assuming an average M of 29.
Answers
(a) The number of molecules contained by the balloon at the given condition is 6,438.97 moles.
(b) The mass of air in the balloon is 186.73 kg.
The given parameters;
volume of the balloon, V = 1500 m³temperature, T = 10⁰C = 273 + 10 = 283 Kpressure, = P = 10.1 kPa = 10,100 PaThe number of molecules contained by the balloon at the given condition is calculated as follows;
[tex]PV = nRT[/tex]
where;
R is ideal gas constant = 8.314 J/mol.Kn is the number of moles air in the balloon;[tex]n = \frac{PV}{RT} \\\\n = \frac{10,100 \times 1500}{8.314 \times 283} \\\\n = 6,438.97 \ moles[/tex]
The mass of air in the balloon is calculated as;
[tex]n = \frac{m}{M} \\\\m = nM\\\\m = 6,438.97\ moles \ \times \ 29 \ g/mol\\\\m = 186.73 \ kg[/tex]
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If an atom should form from its constituent particles,
(a) matter is lost and energy is taken in.
(b) matter is lost and energy is released. .
(c) matter is gained and energy is taken in.
(d) matter is gained and energy is released.
Answers
Answer:
(b) matter is lost and energy is released
Explanation:
When atoms are being formed from its constituent components it weighs less this is called mass defect so the answer would be (b) matter is lost and energy is released.
Given the ionic formula below, what is the charge on ion X? Be sure to
include the sign (+ or -). Li2 x
Answers
Answer:Charge on X = (+ 2)
Explanation:
Charge on one Cl = -1
So Charge on two Cl = -2
The molecule = Neutral = 0 charge
So, to make total charge = 0 , the X should have +2 charge
XCl2 = +2 -2 = 0
X = +2
Alkaline earth metals(Be , Mg , Ca , Sr) form such type of compounds
Explanation:
the process of breaking food is to release energy is called _____
Answers
Answer:
The process by which food is broken down to release energy is called respiration
I hope it helps.
Answer:
Respiration
Explanation:
hope this helps.
Oil does not dissolve in water because
Answers
Answer:
Because oil have apolar molecules, while water have polar molecules
an alloy composed of tin, lead, and cadmium is analyzed. the mole ratio of sn:pb is 2.73:1.00, and the mass ratio of pb:cd is 1.78:1.00. what is the mass percent composition of pb in the alloy
Answers
This problem is describe the mole-ratio composition of an allow composed by tin, lead and cadmium. Ratios are given as Sn:Pb 2.73:1.00 and Pb:Cd is 1.78:1.00, and we are asked to calculate the mass percent compositon of Pb in the allow.
In this case, according to the given information, it turns out possible realize that the following number of moles are present in the alloy, according to the aforementioned ratios:
[tex]2.73mol Sn\\\\1.00molPb\\\\\frac{1.00molPb*1.00molCd}{1.78molPb}= 0.562molCd[/tex]
Next, we calculate the masses by using each metal's atomic mass:
[tex]m_{Sn}=2.73mol*\frac{118.7g}{1mol}=324.05g\\\\ m_{Pb}=1.00mol*\frac{207.2g}{1mol}=207.2g\\\\m_{Cd}=0.562mol*\frac{112.4g}{1mol}=63.2g[/tex]
Thus, the mass percent composition of each metal is shown below:
[tex]\%Sn=\frac{324.05g}{324.05g+207.2g+63.2g} *100\%=54.5\%\\\\\%Pb=\frac{207.2g}{324.05g+207.2g+63.2g} *100\%=34.9\%\\\\\%Cd=\frac{63.2}{324.05g+207.2g+63.2g} *100\%=10.6\%[/tex]
So that of lead is 34.9 %.
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Which of the following is NOT a type of evidence indicating that a chemical change has occurred? *
- fizzing/bubbling
- heat is released
- solubility
- sound is given off
Answers
Answer:
sound is given off
Explanation:
due to a number of scientific research sound that is given off of an object is not due to a chemical reaction.
Dont need work pls help
Answers
In this photograph, a soccer player is about to kick the ball. Use the situation to explain that when two objects interact, the force between them can cause energy to be transferred. In your response, identify the type of energy that each object has before they interact, the forces exerted when the objects interact, and the type of energy that each object has after they interact.
Answers
The explanation to the question is stated as follows:
Newton's first law of motion states that: a body will continue in its state of rest or uniform motion unless an external force acts on it. So then, the ball initially possesses potential energy because it was at rest. While the leg of the soccer player possesses kinetic energy because its in motion.
Thus, when the player hits the ball, a force known as push has been applied. This would ensure that the ball compels and moves in the direction of the applied force. Therefore after the interaction, the leg of the player now possesses potential energy, since it would come to rest after hitting the ball. While the ball would start moving, now possessing kinetic energy.
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