on the test paper. _____11. At the same temperature and pressure, 1.0 liter of CO
(g) and 1.0 liter of. CO2(g) have. (1) equal masses and the same number of.
Regents Chemistry Unit 8 Thermochemistry Practice Test
Name ________________________ Period _________________
Part I Vocabulary (5 points) Select the best vocabulary word, from the list on the left, for each of the statements/definitions placing its letter in the answer space provided for each statement/definition. Part II Multiple Choice (14 points) For questions 11-24, use you knowledge of Chemistry and your reference tables, to select the best answer, of those provided, to each question/statement. Record your answer in the space provided on the test paper. _____11. At the same temperature and pressure, 1.0 liter of CO(g) and 1.0 liter of CO2(g) have (1) equal masses and the same number of molecules (2) different masses and a different number of molecules (3) equal volumes and the same number of molecules (4) different volumes and a different number of molecules _____12. A real gas behaves more like an ideal gas when the gas molecules are (1) close and have strong attractive forces between them (2) close and have weak attractive forces between them (3) far apart and have strong attractive forces between them (4) far apart and have weak attractive forces between them _____13. The solid and liquid phases of water can exist in a state of equilibrium at 1 atmosphere of pressure and a temperature of (1) 273 ⁰C (3) 0°C (2) 100 °C (4) 373 °C ____14. What is the freezing point of sodium? (1) 371°C (3) -98 °C (2) 644 °C (4) 98 °C
_____15. A 15.75-g piece of iron absorbs 1086.75 joules of heat energy, and its temperature changes from 25°C to 175°C. Calculate the specific heat capacity of iron.
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(1) 1.0 J/g ⁰C
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(2) 4.18 J/g ⁰C
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(3) 0.46 J/g ⁰C
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(4) 2.76 J/g ⁰C
_____16. Using your knowledge of chemistry and the information in the Vapor Pressure of Four Liquids chemistry reference table, which statement concerning propanone and water at 50 °C is true? (1) Propanone has a lower vapor pressure and weaker intermolecular forces than water (2) Propanine has a lower vapor pressure and stronger intermolecular forces than water. (3)Propanone has a higher vapor pressure and weaker intermolecular forces than water. (4) Propanone has a higher vapor pressure and stronger intermolecular forces than water.
The graph below represents the uniform heating of a substance, starting with the substance as a solid below its melting point. Use this graph to answer question 17.
_____17. Which line segment represents an increase in average kinetic energy and no change in potential energy? (1) BC (3) ED (2) AB (4) DE _____18. Which phase change is an exothermic process? (1) CO2 (s)→ CO2 (g) (2) CU(s)→ CU(l) (3) NH3(l)→ NH3 (g) (4) Hg(l)→ Hg (s) _____19. A gas occupies a volume of 40.0 milliliters at 20 °C. If the volume is increases to 80.0 milliliters at constant pressure, the resulting temperature will be equal to (1) 20 °C x 80. 0 mL (3) 20 °C x 40.0 mL 40.0 mL 80.0 mL (2) 293 K x 80.0 mL 40.0 mL
(4) 293 K x 40.0 mL 80.0 mL
_____20. How many joules are required to melt 100 grams of water? (1)226000 kJ (2)22600 J (3)33400 kJ (4)33400 J
___1__ 21. Which graph shows the pressuretemperature relationship expected for an ideal gas?
_____22. What is the vapor pressure of water at 105°C? (1) 100 kPa (3) 101.3 kPa (2) 110 kPa (4) 120 kPa _____23. A sample of a gas is contained in a closed rigid cylinder. According to kinetic molecular theory, what occurs when the gas inside the cylinder is heated? (1) The number of gas molecules increases. (2) The number of collisions between gas molecules per unit time decreases. (3) The average velocity (speed) of the gas molecules increases. (4) The volume of the gas decreases. ____24. As a substance changes from a liquid to a gas, the average distance between molecules (1) decrease (2) increase (3) remains the same
Part III Constructed Response (13 points) Answer all questions in this section. Show your work and units. You do not need to use complete sentences. Use sig figs when directed. Heat is added to a sample of liquid water, starting at 80.°C, until the entire sample is a gas at 120.°C. This process, occurring at standard pressure, is represented by the balanced equation below. H2O(ℓ) + heat →H2O(g) 25. In the box below, using the key, draw a particle diagram to represent at least five molecules of the product of this physical change at 120.°C. [2]
26. On the diagram below, complete the heating curve for this physical change and label the phase changes.[1] H2O(s) + heat → H2O (g)
27. Based on data collected during a laboratory investigation, a student determined an experimental value of 322 joules per gram for the heat of fusion of H2O. Calculate the student’s percent error. Your response must include a correct numerical setup and the calculated result. [2] 3.6%
The temperature of a sample of a substance is increased from 20.°C to 160.°C as the sample absorbs heat at a constant rate of 15 kilojoules per minute at standard pressure. The graph below represents the relationship between temperature and time as the sample is heated.
28. What is the boiling point of this sample? [1]_________120⁰C______________ 29 What is the total time this sample is in the liquid phase, only? [1]____3 min_______ 30. Determine the total amount of heat required, in kJ, to completely melt this sample at its melting point. Significant figures required for full credit[2] 30. kJ
31. A 500.000-g sample of liquid water is set on the stove to boil. (a) Assuming that all the energy from the stove is uniformly added, how much energy (J) must be absorbed by the water to completely change all of the liquid water to gaseous water at the boiling point. Show the numerical set-up and record the answer to the ONES place. [2] 1130000J
(b) Calculate the moles of water in the sample. Show the numerical set-up and record the answer according to the rules of significant figures. [1] 27.8 Moles 28 moles (sig fig)
(c) Calculate the amount of energy, in J/mole, absorbed by the water. Show the numerical set-up and record the answer to the ONES place. [1] 1130000J/27.8 Mol = 40647 J/mol best result 113000J/28 mol= 40357 J/mol
