Regular Chemistry Name: ____________________________ #______

Block: __________

Unit 8: Phases of Matter

Homework Packet

1. Forces of Attraction WS

2. Vapor Pressure WS

3. Heating Curve WS

4. Calorimetry WS

5. Phase Diagrams WS

6. Solubility WS

Forces of Attraction WSChemistry

1. Dispersion forces, dipole-dipole forces, and hydrogen bonds are examples of what type of forces?

___________________________________f2. Define an instantaneous dipole.

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3. Define a permanent dipole.

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4. What is the difference between London dispersion forces and dipole-dipole forces?____________________________________________________________________________________

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5. Define a hydrogen bond.

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6. Is a hydrogen bond a true chemical bond? ____________

7. Identify each of the diagrams below as illustrating dipole-dipole forces, London dispersions forces, or hydrogen bonds.

a. __________________________ b. __________________________ c. __________________________

8. Rank the three intermolecular forces in order of increasing strength.

__________________________ < __________________________ < __________________________

*Instantaneous

H2O molecules

*Permanent

Vapor Pressure WSChemistry

Vapor Pressure is the pressure exerted by a vapor when in equilibrium with its condensed phase (solid or liquid). Vapor pressure is an indication of a liquid’s evaporation rate. Boiling occurs when vapor pressure is equal to atmospheric pressure (normal pressure occurs at 1 atm = 760 torr = 760 mmHg = 101.2 kPa).

Directions: Use the vapor pressure graph below of propanone, (CH3)2CO, ethanol, CH3CH2OH, water, H2O, and ethanoic acid, CH3COOH.

1. What is the normal boiling point of each substance?

2. Which compound has the strongest intermolecular forces?

_________________________

3. Which compound has the weakest intermolecular forces?

__________________________

4. What is the relationship between boiling point and strength of intermolecular forces? s

5. At what temperature will each substance boil if atmospheric pressure is 80 kPa?

6. At 50C, what is the vapor pressure of each substance?

7. When we say that a compound has “high vapor pressure,” what does that mean in terms of intermolecular forces?

PropanoneEthanolWater

Ethanoic Acid

Propanone

Ethanol

Water

Ethanoic Acid

Propanone

Ethanol

Water

Ethanoic Acid

Heating Curve WSChemistry

The general equation for calculating heat energy to change the temperature of a substance is:Heat = mass x specific heat x temperature change

Q = mCT*The specific heat of water is 4.18 J/gC.

The general equation for calculating heat energy to undergo a phase change is:

Heat = heat of phase change x moles or gramsQ = Hphase change(moles or grams)

Directions: The heating curve shown to above is a plot of temperature vs. time. It represents the heating of substance X at a constant rate of heat transfer. Answer the following questions using this heating curve:

______ 1. In what part of the curve would substance X have a definite shape and definite volume?

______ 2. In what part of the curve would substance X have a definite volume but no definite shape?

______ 3. In what part of the curve would substance X have no definite shape or volume?

______ 4. What part of the curve represents a mixed solid/liquid phase of substance X?

______ 5. What part of the curve represents a mixed liquid/vapor phase of substance X?

______ 6. What is the melting temperature of substance X?

______ 7. What is the boiling temperature of substance X?

______ 8. In what part(s) of the curve would kinetic energy be increasing?

______ 9. In what part(s) of the curve would potential energy be increasing?

______ 10. In what part of the curve would the molecules of substance X be farthest apart?

______ 11. In what part of the curve would the molecules of substance X have the lowest kinetic energy?

______ 12. In what part of the curve would the molecules of substance X have the greatest kinetic energy?

Calorimetry WS Q = Hphase change(moles or grams) Q = mCTChemistryDirections: Show all work and box your final answers for the following questions.

1. How much energy is needed to change the temperature of 50.0 g or water by 15.0C?

2. How many grams of water can be heated from 20.0C to 75C using 12500.0 Joules of energy?

3. What is the final temperature after 840 Joules is absorbed by 10.0 g of water at 25.0C?

4. The specific heat capacity of aluminum is 0.900 J/gC. How much energy is needed to raise the temperature of a 850. g block of aluminum from 22.8C to 94.6C?

5. How much energy in kilojoules is required to completely change 100 g of water to steam at the boiling point? Hvap = 40.7 kJ/mol

6. Critical Thinking (5 steps!): How much energy in kilojoules is needed to completely change an 18 g block of ice at -5C to steam at 120C? (Hvap = 40.7 kJ/mol and Hfus = 6.02 kJ/mol)

Phase Diagrams WS (Page 1)Chemistry

Phase Diagrams: Phase diagrams show which phase a substance exists under different conditions. There are two variables that control states of matter (phase) of a substance: temperature and pressure. As temperature increases, the substance becomes a vapor, and as pressure increases, condensation occurs. There are two important points on a phase diagram: triple point and critical point. Triple point is where all three phases of matter exist in equilibrium at the same time. Critical point is where the substance cannot exist as a liquid and becomes a supercritical fluid. If a vapor is at critical temperature, an increase in pressure will not change the substance to a liquid.

Directions: For questions 1-6, refer to the phase diagram for mysterious compound X.

1. What is the critical temperature of compound X?

_____________________________

2. If you were to have a bottle containing compound X in your closet, what phase would it most likely be in?

_____________________________

3. At what temperature and pressure will all three phases coexist?

_____________________________

4. If I have a bottle of compound X at a pressure of 45 atm and a temperature of 100C, what will happen if I raise the temperature to 400C?

_____________________________

5. Why can’t compound X be boiled at a temperature of 200C?

6. If I wanted to, could I drink compound X under conditions safe for human consumption? Why or why not?

Phase Diagrams WS (Page 2)Chemistry

Directions: Use the following phase diagrams for water and carbon dioxide to answer the remaining questions.

_____________________________ 7. Point O on the above diagrams represents a temperature andpressure where all three phases exist in equilibrium. What is the point called?

_____________________________ 8. At which point do solid and liquid phases exist in equilibrium?

_____________________________ 9. At which point would a boiling liquid be found?

_____________________________ 10. At which point would sublimation occur?

_____________________________ 11. What is the name of the highest temperature at which it is possible to liquefy a gas with any amount of pressure?

_____________________________ 12. What is the critical pressure for water?

_____________________________ 13. What is the critical pressure for CO2?

_____________________________ 14. Does the solid-liquid equilibrium line on the water diagram have a positive or negative slope?

_____________________________ 15. What phase change occurs going from point C to point B?

_____________________________ 16. Refer to the phase diagram for carbon dioxide. What changes in temperature and pressure would be necessary to go from point D, vapor, to point B, solid?

_____________________________ 17. Refer to the phase diagram for water. What changes in temperature and pressure would be necessary to go from point D, vapor, to point

C, liquid?Solubility WSChemistry

For questions 1-5, an amount of solute is given and the temperature is stated. If all of the solute could be dissolved in 100 g of water at the given temperature, would the resulting solution be unsaturated, saturated, or supersaturated?

1. 60 g KCl at 70C _______________________

2. 10 g KClO3 at 60C _______________________

3. 80 g NaNO3 at 10C _______________________

4. 70 g CaCl2 at 20C _______________________

5. 40 g KNO3 at 50C _______________________

For questions 6-9, a solute and temperature are given. Tell how many grams of each solute must be added to 100 g of water to form a saturated solution at the given temperature.

6. Pb(NO3)2 at 10C ______________

7. Ce2(SO4)3 at 50C ______________

8. NaCl at 20C ______________

9. K2Cr2O7 at 50C ______________

For questions 10 and 11, circle the solution that is more concentrated in each statement.

10. At 10C: a saturated solution of KNO3 or a saturated solution of CaCl2

11. At 50C: a saturated solution of KNO3 or an unsaturated solution of NaNO3 consisting of 90 g of the solute dissolved in 100 g of water

For questions 12 and 13, show your work and box your final answer.

12. If 115 g KNO3 are added to 100 g of water at 35C, how many grams do not dissolve?

13. What mass of KCl would be needed to form a saturated solution if the KCl was dissolved in 200 g of water at 80C?