Unit 6 – Some Review Questions

1. Unit 6 – Some Review Questions States of Matter & Behavior of Gases

2. What Kelvin temperature is equal to 25°C? • 248 K • 298 K • 100 K • 200 K b

3. When the external pressure is 101.3 kPatorr, water will boil at what temperature? • 12.8°C • 14.5°C • 100°C • 18°C c

4. As ice cools from 273 K to 263 K, the average kinetic energy of its molecules will • decrease • increase • remain the same • convert to potential energy a

5. The phase change represented by the equation I2 (s)  I2(g) is called • sublimation • condensation • melting • boiling a

6. As the pressure of a gas at 2 atm is changed to 1 atm at constant temperature, the volume of the gas • decreases • increases • remains the same • is undeterminable b

7. Under the same conditions of temperature and pressure, a liquid differs from a gas because the particles of the liquid • are in constant straight-line motion • take the shape of the container they occupy • have no regular arrangement • have stronger forces of attraction between them d

8. A student investigated the physical and chemical properties of a sample of unknown gas and then investigated the gas. Which statement represents a conclusion rather than an experimental observation? • The gas is colorless. • The gas is carbon dioxide. • When the gas is bubbled in limewater, the liquid becomes cloudy. • When placed in the gas, a flaming splint stops burning. b

9. Which set of values represents STP? • 1 atm and 101.3 K • 1 kPa and 273 K • 101.3 kPa and 0°C • 101.3 atm and 273°C c

10. A gas changes directly to a solid during • fusion • saponification • deposition • decomposition c

11. The phase of a sample of a molecular substance at STP is not determined by its • arrangement of molecules • intermolecular forces • number of molecules • molecular structure c

12. A 220.0-mL sample of helium gas is in a cylinder with a movable piston at 105 kPa and 275 K. The piston is pushed in until the sample has a volume of 95.0 mL. The new temperature of the gas is 310. K. What is the new pressure of the sample? • 51.1 kPa • 243 kPa • 216 kPa • 274 kPa d

13. Which particle diagram represents the arrangement of F2 molecules in a sample of fluorine at 95 K and standard pressure? • 1 • 2 • 3 • 4 b

14. Given the cooling curve of a substance: During which intervals is potential energy decreasing and average kinetic energy remaining constant? • AB and BC • DE and BC • AB and CD • DE and EF b

15. What is the boiling point of propanone if the pressure on its surface is 48 kilopascals? • 25°C • 30°C • 35°C • 40°C c

16. Using your knowledge of chemistry and the information in Reference Table H, which statement concerning propanone and water at 50°C is true? • Propanone has a higher vapor pressure and stronger intermolecular forces than water. • Propanone has a higher vapor pressure and weaker intermolecular forces than water. • Propanone has a lower vapor pressure and stronger intermolecular forces than water. • Propanone has a lower vapor pressure and weaker intermolecular forces than water. a

17. Two gas tanks contain nitrogen, N2(g), and oxygen, O2(g). The volume of both tanks is 20 L, the pressure in each tank is 2.0 atm, and the temperature of each tank is 330 K. What can be said of the number of molecules in each tank? • There are more N2(g) molecules than O2(g) molecules. • There are more O2(g) molecules than N2(g) molecules. • They both have the same number of gas molecules. • Cannot be determined. c