Unit 7 Review

  1. Compare and contrast solids, liquids, and gases.
  1. Convert
  2. -16 °C to K
  3. 380 K to °C
  4. For each of the changes of state listed, state what phase it starts at and what state it is going to.
  5. Freezing ______
  6. Melting ______
  7. Boiling ______
  8. Condensation ______
  9. Sublimation ______
  10. Deposition ______
  11. Which changes of state listed above are exothermic processes (i.e. lose kinetic energy as heat to the surroundings)?
  1. Which changes of state are endothermic processes?
  1. For each of the following q values, determine if the sign is negative or positive.
  1. The system absorbs heat ______
  2. Heat is released from the system______

Solve each equation below:

  1. A student finds a rock on the way to school. In the laboratory he determines that the volume of the rock is 22.7 cm3, and the mass is 39.943 g. What is the density of the rock?
  1. What is the mass of a 350 cm3 sample of pure silicon with a density of 2.336 g/cm3?
  1. Pure gold has a density of 19.32 g/cm3. How large would a piece of gold be if it had a mass of 318.97 g?
  1. A cubic sample of quartz has a density of 2.65 g/cm3 and the length of one side of the cube is 4 cm. What is the mass of the quartz sample?
  1. A student was asked to determine the density of a spherical object, but she couldn’t remember the formula for finding the volume of a sphere. She placed the sphere into a graduated cylinder containing 3.0 ml of water. The water level rose to 4.5 ml. Then she found the mass of the sphere to be 4.7 g. Calculate the density.
  1. A 120g sample of an unknown substance was heated from 15oC to 30oC. The substance absorbed 458 joules of energy. What is the specific heat of this substance?
  1. If the temperature of 28 g of ethanol increases from 15oC to 65.5oC, how much heat was absorbed by the ethanol? (Specific heat ethanol = 2.44 J/goC)
  1. How many grams of water would require 2.20 x 104 joules of heat to raise its temperature from 34.0°C to 100.0°C? The specific heat of water is 4.184 J/g∙°C
  1. A cube of gold weighing 192.4g is heated from 30.0°C to some higher temperature, with the absorption of 226 joules of heat. The specific heat of gold is 0.030 J/g∙°C. What was the final temperature of the gold?
  1. A lump of chromium (Cr) has a mass of 92.5 grams and a temperature of 89.5oC. It is placed into a calorimeter with 75.2 g of water at 20.5oC. After stirring, the final temperature of the water, Cr metal, and calorimeter is 27.4oC. What is the specific heat of Cr metal?
  1. A 324 g sample of a metal with a specific heat of 0.82 J/g°C is heated to 100.0°C then placed in a 50.0 g sample of water at 20.0°C. What is the final temperature of the metal and the water?
  1. Explain why (in terms of molecular kinetic energy) the heat of vaporization is seven times larger than the heat of fusion for water.
  1. A liquid will begin to boil when ______= ______.
  1. What is the specific condition of pressure for the normal values of freezing or boiling for a liquid?
  1. a) What is the critical point for a liquid? And b) what is the triple point for a substance?

a)b)

  1. Draw a cooling curve for water starting at 110°C going to -10°C (y-axis is °C and x-axis is time)
  1. Identify the letters on the phase diagram shown below and place your response in the spaces provided.

A: ______

B:______

C: ______

D: ______

E: (arrow)______