Name:______
Grade 11B/G Take Home Test #3
Thermodynamics
Due Friday December 3, 2010
______
Instructions:
· Please answer each of the following questions in the space provided.
· Test will be marked out of 100; each question is worth 5 marks
· 5 marks will be deducted per day late.
· There will be no bonus questions.
Talk about heat transfer!
1. What is an endothermic chemical reaction? Please give an example.
2. What is an exothermic chemical reaction? Please give an example.
3. Consider the diagram below,
a) What would the temperature of the mixture be compared to that of the hot water and that of the cold water?
b) What type of energy is being transferred? Please explain how this transfer is occurring.
4. If you were to order a cup of coffee, would you want the cup to have a high heat capacity or a low heat capacity before you carry it out? Please explain your answer.
5. Please define Heat Capacity and Molar Heat Capacity.
6. A 30.0 g sample of water at 280 K is mixed with 50.0 g of water at 330 K. Calculate the final temperature of the mixture assuming no heat loss to the surroundings.
7. A 70.0 g sample of water at 95.00°C is mixed with 50.0 g of water at 135.0°C. Calculate the final temperature of the mixture assuming no heat loss to the surroundings.
8. If I burn 0.315 moles of hexane (C6H14) in a bomb calorimeter containing 5.65 liters of water, what’s the molar heat of combustion of hexane is the water temperature rises 55.40 C? The heat capacity of water is 4.184 J/g0C.
9. Calculate the number of joules released when 75.0 grams of water are cooled from 100.0˚C to 27.5˚C.
10. The specific heat of gold is 0.128 J/g˚C. How much heat would be needed to warm 250.0 grams of gold from 25.0˚C to 100.0˚C?
11. The specific heat of zinc is 0.386 J/g˚C. How many joules would be released when 454 grams of zinc at 96.0˚C were cooled to 28.0˚C? What would be the final temperature if 3.31 x 103 joules were added to 18.5 grams of water at 22.0˚C?
12. A sample of lead, specific heat 0.138J/g˚C, released 1.20 x 103J when it cooled from 93.0˚C to 29.5˚C. What was the mass of this sample of lead?
13. Calculate the specific heat of platinum if 1092 joules of heat were released when 125 grams of platinum cooled 65.2 Celsius degrees.
14. How much heat is required to raise 15.0 g of water from 20.0 ˚C to 50.0 ˚C?
15. A 1.29 g piece of lead has a temperature of 26.0 ˚C. If it loses 1.90 J of heat to its surroundings, what is its new temperature. Specific heat of lead is 0.128 J/g˚C
16. A 55.1 g piece of metal is heated to a temperature of 45.1 ˚C, and placed into a cup containing 359 g of water at 20.0 ˚C. The final temperature of the water and metal is 22.3˚C.
a. How much heat energy did the water absorb?
b. How much heat energy did the metal release to the water?
c. What is the specific heat of the metal?
17. Compound A is burned in a bomb calorimeter that contains 2.50 liters of water. If the combustion of 0.175 moles of this compound causes the temperature of the water to rise 45.0˚ C, what is the molar heat of combustion of compound A? The heat capacity of water is 4.184 J / g˚C.
18. The molar heat of combustion of compound C is 1,250 kJ/mol. If I were to burn 0.115 moles of this compound in a bomb calorimeter with a reservoir that holds 2.50 L of water, what would the expected temperature increase be?
Some Multiple Choice Questions
19. The specific heat capacity of Fe(s) is 0.45 J/g°C and that of Al(s) is 0.90 J/g°C.
Given the same mass of solid aluminum (Al) and iron (Fe), which of the following is true?
A) / The amount of energy required to raise the temperature of Fe one degree Celsius is twice that of Al.B) / The amount of energy required to raise the temperature of Al one degree Celsius is twice that of Fe.
C) / The amount of energy removed from Fe that has cooled one degree Celsius is twice that of Al.
D) / The same amount of energy is required to raise the temperature of Fe and Al one degree Celsius.
20. You have 250 mL of coffee, whose temperature is 25°C. You add 50.0 mL of water, whose temperature is 95°C.
What will be the final temperature of the coffee?
(Assume that coffee has the same density and specific heat capacity as water.)
A) / 33°C / C) / 44°CB) / 37°C / D) / 60°C
21. A 1.00 ´ 102 mL sample of water at 90.0°C is placed into a calorimeter containing 1.00 ´ 102 mL of water at 25.0°C.
What is the final temperature of the water in the calorimeter?
A) / 57.5°C / C) / 50.0°CB) / 52.5°C / D) / 37.0°C
22. Magnesium burns in oxygen according to the following equation:
Mg(s) + O2(g) ® MgO(s) DH = -6.00 ´ 102
23. If 6.00 g of magnesium metal is burned in an excess of oxygen, what energy will be released by this reaction?
A) / 1.48 ´ 102 KjB) / 1.92 ´ 102 kJ
C) / 3.60 ´ 102 kJ
D) / 2.43 ´ 103 kJ
24. Everyday, phenomena take place all around us.
Which of the following may be identified as exothermic processes?
1. Dew forming on blades of grass
2. Melting snow and ice on a driveway by adding salt
3. Drying a wet T-shirt on a clothesline
4. Freezing meat to preserve it
5. Burning propane gas in a stove
A) / 2 and 3 / C) / 1, 2 and 3B) / 4 and 5 / D) / 1, 4 and 5
The combined gas law
25. The standard value for R is 8.31 . Over time atmospheric pressure has been measured using many different units, including:
101.3 kPa
1 atmosphere (atm)
760 mm Hg
407 inches H2O
What would be the ideal gas constant, R, if the pressure were measured in inches H2O?
(Use standard units forV,n,T.)
26. Antoine Lavoiser produced oxygen by heating mercury (II) oxide (HgO) according to the following equation:
2 HgO(s) ® 2 Hg(l) + O2(g)
What volume of oxygen will be produced by heating 54.0 g of mercury (II) oxide at STP?
27. A science student would like to identify a pure gas sample. She finds the following information:
Mass of empty container / 4.40 gMass of container + unknown gas / 6.00 g
Volume / 1210 mL
Temperature / 18°C
Pressure / 102 kPa
Which of the following is the unknown gas? (show all your work)
H2, / O2, / OCl2, / BCl328. Nitroglycerine, C3H5(ONO2)3, has a density of 1.59 g/mL. When it explodes, the following reaction takes place:
4 C3H5(ONO2)3 (l) ® 12 CO2(g) + O2(g) + 6 N2(g) + 10 H2O(g)
What volume of water vapour, measured at STP, is produced when 1.0 x 102 mL of nitroglycerine explodes?
FORMULAS
Q = mcDTPV = n RT
PHYSICAL CONSTANTS
SYMBOL / NAME / VALUE
/ Specific heat capacity of water / 4190 J/(kg·°C)
or 4.19 J/(g·°C)
/ Density of water / 1.00 g/mL
R / Molar gas constant / 8.31 kPa · L/(mol·K)
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