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AP Chem > Unit 3 Test > Flashcards

Unit 3 Test Flashcards

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1
Q

Effusion

A

the escape of gas molecules through a tiny hole into an evacuated space.

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2
Q

How are volume and moles of gas related when it comes to the ideal gas law?

A

They are directly related. If the volume increases, then the moles of a gas increases.

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3
Q

Why would a Maxwell-Boltzmann graph be shifted to the right?

A

As the temperature increases, the curve
flattens out and the most probable speed rises (shifts
right.)

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4
Q

What does the peak of a Maxwell-Boltzmann Distribution graph mean?

A

It means that is the most probable speed

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5
Q

How are temperature and pressure related when it comes to the ideal gas law?

A

They are directly related. If the pressure increases, then the temperature increases.

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6
Q

CO2 melts at 78 C and SiO2 melts at 1650 C. Explain the difference in melting points.

A

CO2 is molecular solid and only IMFs are being broken when it is melted. However, SiO2 is a covalent network and covalent bonds require a lot to be broken.

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7
Q

Partial Pressure Formula

A

Total pressure= Pressure of A + Pressure of B + Pressure of C….

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8
Q

Practice 2014 frq number 4 and 6; 2015 frq number 2; 2017 number 1; 2021 number 7

A
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9
Q

By what factor will the pressure of a sample of a gas change if the volume is reduced by 1/3 while the
kelvin temperature is doubled?

A

Using the ideal gas law equation change it to Pressure= Temperature/ Volume. Then the Temperature is doubled and the volume is reduced by 1/3 so it is 2/3. So the equation is 2 divided by 2/3 and the final answer is 3x factor.

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10
Q

Why would dichloromethane(a polar molecule) have a higher vapor pressure than carbon tetrachloride(a nonpolar molecule)?

A

Typically as IMFs increase vapor pressure decreases. However, in this case, dichloromethane has weaker dipole-dipole and LDFs combined compared to the strong LDFs in carbon tetrachloride.

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11
Q

Retention factor formula

A

Distance moved by sample/ Distance moved by solvent

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12
Q

On a chromatography paper what solutions will move farther?

A

The solutions that have more in common with the mobile phase(the solvent). So whatever is closest to the solvent front is most like the solvent.

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13
Q

Distillation

A

Separates substances based on their IMFs and their different vapor pressures/boiling points

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14
Q

Heterogenous Mixtures

A

The macroscopic properties of the mixture could vary

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15
Q

Stationary phase

A

Chromatography paper

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16
Q

Study 3.1-3.3 quizlet

A
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17
Q

Kinetic Molecular Theory(KMT)

A
  • Gases are in continuous motion and they move in straight lines and only change directions when they collide with the container wall or other molecules
  • IMFs between gases are negligible because they are so far apart
  • The combined volume of all the molecules of the gas is negligible compared to the container the gas is in
  • The molecules in a gas are negligibly small compared to the distance between them
  • Collisions are elastic(no kinetic energy is lost)
  • Pressure inside container comes from collisions of the particles on the container’s walls
  • Average kinetic energy is directly proportional to the temperature
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18
Q

Ethane and methanal have the same molar mass. One of these two molecules are a liquid at room temperature. Ethane is nonpolar and methanol is polar. Predict the substance that is liquid at room temperature.

A

Methanal is the liquid because both of these liquids are covalent meaning they are either liquids or gases. So, methanol is a liquid because it is polar and harder to break apart unlike ethane.

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19
Q

Solubility

A

The extent in which a solute will dissolve into a solvent from a solution

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20
Q

Mobile phase

A

The solvent that the chromatography paper is in

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21
Q

Which of the following would produce the lowest vapor pressure?
a) C3H8
b) MgCl2
c) NH3
d) H2O

A

B) MgCl2 because as IMFs increase vapor pressure decreases and ionic solids have higher IMFs than molecular solids like the rest of the options.

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22
Q

Ion
- Two types or parts of an ion and “definition”

A

A metal and a nonmetal
- Cation(positive/ metal), Anion(negative/ nonmetal)

23
Q
A
24
Q

How are pressure and volume related when it comes to the ideal gas law?

A

They are inversely related. If pressure increases, then volume decreases

25
Q

Do practice problems in 3.4 video 3 and review 3.4 questions in packet(look at answer key on classroom when reviewing rather than packet); 3.5 video 1 and 2 and 3.5 questions in packet; 3.6 video 1 and 3.6 questions in packet; 3.7 video and packet questions, 3.9 video 2

A
26
Q

How does a boiling point increase in relation to polarizability?

A

The larger and more polarizable something is the higher the boiling point is

27
Q

What type of molecules experience stronger IMFs?

A

Larger molecules experience stronger IMFs

28
Q

Concentration vs Molarity

A

Same thing and the equation is on the equation sheet under molarity

29
Q

How are the number of moles and pressure related when it comes to the ideal gas law?

A

They are directly related. If the number of moles increases, then the pressure increases.

30
Q

The more particles, the _______ concentration

A

higher

31
Q

How many milliliters in a liter?

A

1000

32
Q

When does the KMT start to break down?
AKA- when are there deviations from the ideal gas law?

A

When real gases come into play. They thrive off of high pressure and/or low temperature because with both of these the gas is going to have IMFs because they are constantly interacting and the KMT says that gases have no attractive forces. Also, there is going to be volume.

33
Q

Anions are always __________ than cations

A

Larger

34
Q

What do molecular compounds dissolve in?

A

Nonpolar solvents

35
Q

What is the density formula when related to the ideal gas law?

A

Density= PM/ RT
M= molar mass

36
Q

Properties of real gas behavior

A
  • There are attractive forces and the gases are able to condense
  • Molecules do have volume
  • Significant molecular size of gas particles
37
Q

Mole Fraction
- Definition
- Formula

A
  • Ratio of the moles of one gas in a mixture to the total number of moles of gases
  • Number of specific particle/ total number of particles in mixture
38
Q

What do ionic compounds dissolve in?

A

Polar solvents

39
Q

Cl2 heat vaporization is 24.1 and its dipole moment is 0. HCl heat vaporization is 16.3 and its dipole moment is 1.5.

Identify the IMFs for both and explain the difference in heat vaporization in terms of relative strength of IMFs.

A

Cl2 has LDFs only because it is nonpolar. However, HCl has LDFs and dipole-dipole because it is polar. The heat vaporization for HCl is higher because its LDFs are stronger than the LDFs and dipole-dipole in the HCl which means its atoms are pulled strongly together and harder to pull apart and vaporize. a

40
Q

How to analyze thin-layer chromatography?

A

The more nonpolar the sample is the farther it will travel. The more polar the sample is, the shorter it will travel.

41
Q

Why are ionic solids brittle?

A

Because they’re made up of positive and negative ions arranged in a neat, repeating pattern. When you apply force, like trying to bend or hit them, the ions can shift. If the positive ions get too close to other positive ions (or negative to negative), they repel each other, causing the solid to crack or break rather than bend.

42
Q

Dipole-induced dipole interactions
- How do they increase?
- When do these occur?

A
  • They are typically stronger when the two molecules are close in proximity.
  • These occur between nonpolar and polar molecules, like water and oxygen
43
Q

Ideal gases behave the _______ regardless of __________

A

Same; Chemical Identity

44
Q

If you are comparing two gases and know both of their masses, what can you say about their velocity and about their kinetic energy?

A

The gas with the lower mass will have a greater velocity than the heavier gas.

The gas with the heavier mass will have the greater kinetic energy.

45
Q

Percent yield formula

A

Actual yield/ Max possible yield times 100

46
Q

Diffusion

A

the spread of one substance throughout a space
or a second substance

47
Q

Homogenous Mixtures

A

The macroscopic properties of the mixture do not vary

48
Q

How can you determine what has stronger IMFs when looking at two molecules of different sizes and different IMFs?

A

You have to use data like boiling point

49
Q

When comparing two elements, how do you know which one has the lower boiling point?

A

It will be the one with less electrons because it is less polarizable

50
Q

Which type of chromatography works best with amino acids?

A

Thin layer chromatography

51
Q

In distillation what is extracted first?

A

The nonpolar things are extracted first

52
Q

Hydration
- Definition
- What type of molecules are more strongly hydrated?

A
  • The process where the water molecules surround the ions to dissolve them
  • Smaller ions and large charges
53
Q

What are the 3 steps for a solution to form?

A

1) The solute particles must separate(energy required)
2) The solvent particles must separate(energy required)
3) The solute and solvent particles must come back together(energy released)

54
Q

Practice #8, 15, 21 on progress check multiple choice

A

AP Chem (6 decks)

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