1. Base your answer to the following question on the information below.

Cold packs are used to treat minor injuries. Some cold packs contain NH4NO3(s) and a small packet ofwater at room temperature before activation. To activate this type of cold pack, the small packet mustbe broken to mix the water and NH4NO3(s). The temperature of this mixture decreases toapproximately 2°C and remains at this temperature for 10 to 15 minutes.State the direction of heat flow that occurs when the activated cold pack is applied to the body.

Base your answers to questions 2 and 3 on the information below.

Heat is added to a 200.-gram sample of H2O(s) to melt the sample at 0°C. Then the resulting H2O( ) is heated to a final temperature of 65°C.

2. In the space below, show a numerical setup for calculating the total amount of heat required to raisethe temperature of the H2O( ) from 0°C to its final temperature.

3. Determine the total amount of heat required to completely melt the sample.

Base your answers to questions 4 through 6 on the information below.

A sample of helium gas is in a closed system with a movable piston. The volume of thegas sample is changed when both the temperature and the pressure of the sample are increased.The table below shows the initial temperature, pressure, and volume of the gas sample, as well asthe final temperature and pressure of the sample.

4. Compare the total number of gas particles in the sample under the initial conditions to the total numberof gas particles in the sample under the final conditions.

5. Convert the final temperature of the helium gas sample to degrees Celsius.

6. In the space below show a correct numerical setup for calculating the final volume of the helium gassample.

7. A liquid boils when the vapor pressure of the liquid equals the atmospheric pressure on the surface ofthe liquid. Using Reference Table H, determine the boiling point of water when the atmosphericpressure is 90. kPa.

8. Base your answer to the following question on the following paragraph.

The boiling point of a liquid is the temperature at which the vapor pressure of the liquid is equalto the pressure on the surface of the liquid. The heat of vaporization of ethanol is 838 joules pergram. A sample of ethanol has a mass of 65.0 grams and is boiling at 1.00 atmosphere.

Calculate the minimum amount of heat required to completely vaporize this sample of ethanol. Yourresponse must include both a correct numerical setup and the calculated result.

Base your answers to questions 9 through 11 on onthe information below.

A 100.0-gram sample of NaCl(s) has an initialtemperature of 0°C. A chemist measures thetemperature of the sample as it is heated. Heat is not added at a constant rate. The heating curve forthe sample is shown below.

9. Identify one line segment on the curve where theNaCl sample is in a single phase and capable ofconducting electricity.

10.Identify one line segment on the curve where theaverage kinetic energy of the particles of the NaClsample is changing.

11. Determine the temperature range over which theentire NaCl sample is a liquid.

Base your answers to questions 12 through 14 on the information below.

The temperature of a sample of a substance is increased from 20.°C to 160.°C as the sampleabsorbs heat at a constant rate of 15 kilojoules per minute at standard pressure. The graph belowrepresents the relationship between temperature and time as the sample is heated.

12. What is the total time this sample is in the liquid phase, only?

13. Use the key below to draw at least nine particles in the box, showing the correct particle arrangementof this sample during the first minute of heating.

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14. What is the boiling point of this sample?

15. Base your answer to the following question on the information below.

Air bags are an important safety feature in modern automobiles. An air bag is inflated inmilliseconds by the explosive decomposition of NaN3(s). The decomposition reaction produces N2(g), as well as Na(s), according to the unbalanced equation below.

NaN3(s) ®Na(s) + N2(g)When the air bag inflates, the nitrogen gas is at a pressure of 1.30 atmospheres, a temperature of 301K, and has a volume of 40.0 liters. Calculate the volume of the nitrogen gas at STP. Your responsemust include both a correct numerical setup and the calculated volume

16. A sample of oxygen gas in one container has a volume of 20.0 milliliters at 297 K and 101.3 kPa. Theentire sample is transferred to another container where the temperature is 283 K and the pressure is94.6 kPa. Show a correct numerical setup for calculating the new volume of this sample of oxygengas.

Base your answers to questions 17 through 19 on the information below

A 5.00-gram sample of liquid ammonia is originally at 210. K. The diagram of the partialheating curve below represents the vaporization of the sample of ammonia at standard pressuredue to the addition of heat. The heat is not added at a constant rate.

17. Determine the total amount of heat required to vaporize this 5.00-gram sample of ammonia at itsboiling point.

18. Describe what is happening to both the potential energy and the average kinetic energy of themolecules in the ammonia sample during time interval BC. Your response must include bothpotential energy and average kinetic energy.

19. Calculate the total heat absorbed by the 5.00-gram sample of ammonia during time interval AB. Yourresponse must include both a correct numerical setup and the calculated result.

Base your answers to questions 20 and 21 on the properties of propanone.20. A liquid's boiling point is the temperature at which its vapor pressure is equal to the atmospheric

pressure. Using Reference Table H, what is the boiling point of propanone at an atmospheric pressureof 70 kPa?

21. Explain, in terms of molecular energy, why the vapor pressure of propanone increases when itstemperature increases.

Answer KeyRegents Review - Unit 6 - Physical Behavior of Matter

1. Acceptableresponses include,but are not limitedto: • Heat flowsfrom the body to thecold pack from thearea of highertemperature to thearea of lowertemperature.

2. q = (200. g)(4.18J/g•°C)(65°C) or(200)(4.18)(65)

3. 66800 J or 6.68 × 104 J

4.5.6.7. 97°C ± 1°C.8. Examples:

– (65)(838)– 5.45 104 J – 54500 J

9. CD10. AB

CD11. 801°C to 1465°C12. 3.0 min 0.2 min13.

14. 120.°C 2°C.15. 47.2 L

V2 = (273 K)(1.30atm)(40.0 L) (301K)(1.00 atm)(273)(1.30)(40.0) (301)(1.00)

16. Acceptableresponses include,but are not limitedto:

17. 6850 J18. The potential energy

of the ammoniamolecules increasesand the averagekinetic energy of theammonia moleculesremains the same.

19. q = mC T = (5.00g)(4.71 J/g • K)(30.K)(5)(4.71)(30)710 J

20. 45°C (±2).21. Acceptable

responses include,but are not limitedto:As the temperatureincreases, moremolecules haveenough energy toescape the liquidphase.