Unit 5 Test--Just a Phase: Liquids and Solids

Multiple Choice (Choose the best answer.)

  1. On the graph at right, where would it be possible to find only a gas present?

  2. On the graph above, which letter indicates the boiling point?

  3. On the graph above, where are all the places it would be possible to find a liquid present?

    B only

    C only

    B & C only

    C & D only

    B, C, & D only

  4. On the graph above, where is the potential energy primarily increasing?

    B only

    C only

    B & D only

    C & D only

    B, C, & D only

  5. In comparison with liquids and gases, solids are:

    more dense.

    more compressible.

    less organized.

    more likely to flow to fill their containers

    more than one of the above are correct

  6. The amount of heat to raise the temperature of 1 gram of a substance 1 oC is called:

    heat capacity

    enthalpy

    specific heat

    heat of fusion

    heat of vaporization

  7. Water could be made to boil at 92 oC by:

    lowering the external air pressure.

    raising the external air pressure.

    increasing the pressure on the water.

    More than one answer is possible.

    None of these would work.

  8. The heat absorbed by one mole of a substance in changing from a liquid to a solid at constant temperature is symbolized by which of these symbols?

    Hsoln

    Hsolid

    Hfusion

    Hvap

    None of these is correct.

  9. A sample of glass that has a mass of 6.0 g gives off 12 J of heat. If the temperature of the sample changes by 4.0 oC, what is the specific heat of the glass?

    2.0 J/(g oC)

    1.1 J/(g oC

    0.50 J/(g oC)

    0.45 J/(g oC)

    None of these is correct.

  10. How many calories are required to raise the temperature of 75.0 g of water from 20 oC to 50 oC?

    1500 cal

    2250 cal

    3750 cal

    75.0 cal

    None of these.

  11. How much heat, is required to melt 54.0 g of ice at 0 oC into water at 0 oC ? The heat of melting is 1.44 Kcal/mol.

    0.0264 Kcal

    77.4 Kcal

    4.32 Kcal

    2.14 Kcal

    None of these is correct.

  12. Substance "X" requires 26.5 Joules to vaporize 10.0 g of "X" at its normal boiling point. If the molecular weight of substance "X" is 7.00 g/mol, what is its heat of vaporization?

    37.9 g/mol

    0.379 J/mol

    18.6 J/mol

    1860 J/mol

    None of these are correct.

    Questions 13-15 refer to the vapor pressures of various liquids shown in the figure at right.

  13. The normal boiling point of ethanol is:

    ~ 55 oC

    ~ 65 oC

    ~ 75 oC

    ~ 80 oC

    ~100 o

  14. If beakers of each of the substances shown in the figure were placed under a bell jar and the pressure reduced to 20 KPa, which of the liquids would boil at room temperature (~20 oC)?

    chloroform only

    chloroform and ethanol only

    chloroform, ethanol, and water only

    all of the liquids would boil

    none of the liquids would boil

  15. Which of the substances would you predict has the highest melting point?

    chloroform

    ethanol

    water

    ethanoic acid

    impossible to tell

Problem-Solving (Show all work and units. Pay attention to significant figures.)

1. A 10.0 g piece of metal at 75.0 oC is placed into a calorimeter containing 50.0 g of water at 20.0 oC. The final temperature of the water is 25.0 oC.

a) What are the temperature changes of the water and metal?


b) Calculate the energy gained by the water.


c) Calculate the energy lost by the metal.


d) Calculate the specific heat of the metal



2. How much energy in Kcal would it take to melt 90.0 g of ice at 0 oC and warm the resulting liquid to 65 oC? ( Hmelting = 1.44 Kcal/mol)






3. Use the graph at right to explain why the vapor pressure of a substance increases as the temperature of that substance increases. Your explanation should be accompanied by an alteration of the graph.

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