Name ………………………………………………………………..
Sample Regents Questions from
June 2008 and June 2009
Period…………….
1. Standard pressure is equal to
(1) 1 atm
(2) 1 kPa
(3) 273 atm
(4) 273 kPa
2. At 65°C, which compound has a vapor pressure
of 58 kilopascals?
(1) ethanoic acid (3) propanone
(2) ethanol
(4) water
3. At STP, which 2.0-gram sample of matter
uniformly fills a 340-milliliter closed container?
(1) Br2(l)
(3) KCl(aq)
(2) Fe(NO3)2(s) (4) Xe(g)
4. A person with a body temperature of 37°C holds
an ice cube with a temperature of 0°C in a room
where the air temperature is 20.°C. The
direction of heat flow is
(1) from the person to the ice, only
(2) from the person to the ice and air, and from
the air to the ice
(3) from the ice to the person, only
(4) from the ice to the person and air, and from
the air to the person
5. At standard pressure, which element has a
freezing point below standard temperature?
(1) In
(2) Ir
(3) Hf
(4) Hg
6. Two solid samples each contain sulfur, oxygen,
and sodium, only. These samples have the same
color, melting point, density, and reaction with
an aqueous barium chloride solution. It can be
concluded that the two samples are the same
(1) compound
(2) element
Unit 7: Matter and Thermochemistry
(3) mixture
(4) solution
7. Which process increases the potential energy of
the particles of a sample?
(1) condensation (3) solidification
(2) deposition
(4) vaporization
Question Set #5
8. Which equation represents a physical change?
(1) H2O(s) + 6.01 kJ → H2O(l)
(2) 2H2(g) + O2(g) → 2H2O(g) + 483.6 kJ
(3) H2(g) + I2(g) + 53.0 kJ → 2HI(g)
(4) N2(g) + 2O2(g) + 66.4 kJ → 2NO2(g)
9. Which liquid has the lowest vapor pressure at
65°C?
(1) ethanoic acid (3) propanone
(2) ethanol
(4) water
10. Which substance can not be broken down by a
chemical reaction?
(1) ammonia
(2) argon
(3) methane
(4) water
11. In which sample is the average kinetic energy of
the particles greatest?
(1) 10. mL of HCl(aq) at 25°C
(2) 15 mL of HCl(aq) at 20.°C
(3) 10. mL of H2O(l) at 35°C
(4) 15 mL of H2O(l) at 30.°C
12. A thermometer is in a beaker of water. Which
statement best explains why the thermometer
reading initially increases when LiBr(s) is
dissolved in the water?
(1) The entropy of the LiBr(aq) is greater than
the entropy of the water.
(2) The entropy of the LiBr(aq) is less than the
entropy of the water.
(3) The dissolving of the LiBr(s) in water is an
endothermic process.
(4) The dissolving of the LiBr(s) in water is an
exothermic process.
13. Which 1-mole sample has the least entropy?
(1) Br2(s) at 266 K
(2) Br2(l) at 266 K
(3) Br2(l) at 332 K
(4) Br2(g) at 332 K
14. Which two particle diagrams represent mixtures of diatomic elements?
(1) A and B
(2) A and C
(3) B and C
(4) B and D
15. The graph below represents the relationship between temperature and time as heat is added to a sample of
H2O.
Which statement correctly describes the energy of the particles of the sample during interval BC?
(1) Potential energy decreases and
average kinetic energy increases.
(2) Potential energy increases and
average kinetic energy increases.
(3) Potential energy increases and
average kinetic energy remains the same.
(4) Potential energy remains the same and
average kinetic energy increases.
Base your answers to questions 16 and 17 on the information below.
At a pressure of 101.3 kilopascals and a temperature of 373 K, heat is removed from a sample of water vapor,
causing the sample to change from the gaseous phase to the liquid phase. This phase change is represented by
the equation below.
H2O(g) → H2O(l) + heat
16. Explain, in terms of particle arrangement, why entropy decreases during this phase change. [1]
17. Determine the total amount of heat released by 20. grams of water vapor during this phase change. [1]
Base your answers to questions 18 through 19 on the information below.
Boiling Point (K)
18. On the grid below, mark an appropriate scale on the axis labeled “Boiling Point (K).” [1]
19. On the same grid, plot the data from the data table. Circle and connect the points. [1]
0
10.
20.
30.
40.
Molar Mass (g/mol)
50.
60.
20. Based on the data in the table, state the relationship between the boiling point at 1 atmosphere and molar
mass for these four substances. [1]
21. State, in terms of intermolecular forces, why the boiling point of propane at 1 atmosphere is lower than the
boiling point of butane at 1 atmosphere. [1]
Base your answers to questions 22 through 23 on the information below. A 150.-gram liquid sample of stearic
acid, C17H35COOH, is cooled at a constant rate. The temperature of the sample is recorded at 2-minute intervals
in the data table below.
22. Identify the physical change occurring during the time interval 4 minutes to 10. minutes. [1]
23. Determine the gram-formula mass of stearic acid. [1]
Thermochemistry Problems
*Show Units*
- if there is a change in temperature, use q = mC∆T
- if there is a change in phase, use q = mHf or q = mHv
24. How much energy must be absorbed by 20.0 g of water to increase its temperature from 283ºC to 303ºC?
25. When 15.0 g of steam drops in temperature from 275 ºC to 250 ºC, how much heat energy is released?
26. If 720.0 g of steam at 400 ºC absorbs 800 kJ of heat energy, what will be its increase in temperature?
27. If it takes 41.72 joules to heat a piece of gold with a mass of 18.69 g from 10 ºC to 27 ºC, what is the
specific heat of the gold?
28. A certain mass of water was heated with 41, 840 J, raising its temperature from 22 ºC to 28.5 ºC. Find the
mass of the water.
29. What would be the temperature change if 15 g of water absorbed 75 J of heat?
30. The heat of vaporization of a liquid is 1344 J/g. What is the minimum number of joules needed to change
40.0 g of the liquid to vapor at the boiling point?
31. Determine the energy required to melt 74.5 g of ice at 0 ºC. Is this reaction endothermic or exothermic?
32. Determine the energy needed to convert 52.6 g of steam to liquid water. Is this endothermic or exothermic?
33. Refer to the graph below, which shows a cooling curve for a substance in a gaseous phase that was cooled
during a 24-minute period. The substance gave off heat at a constant rate of 40 J/min. during the entire
time. The 24-minute period has been divided into five time intervals, labeled I, II, III, IV, and V.
a) What is the boiling point of the substance?
b) In which interval or intervals are there two phases present?
c) During which interval or intervals is all of the substance a gas?
d) During interval IV, what happens to the kinetic energy of the molecules in the substance?
e) During interval IV, what happened to the potential energy of the molecules in the substance?
f) What is the heat of vaporization for the substance?
g) What is the heat of fusion for the substance?
h) Why is the heat of vaporization always bigger than the heat of fusion?