5.2 Calorimetry
Measuring heat exchanged between a reaction and its surroundings in coffee-cup and bomb calorimeters, and extracting heats of reaction from that data.
12 exercises
5.2 Exercise 2
Would the amount of heat measured for the reaction in the example be greater, lesser, or remain the same if we used a calorimeter that was a poorer insulator than a coffee cup calorimeter? Explain your answer.
5.2 Exercise 4
Would the amount of heat absorbed by the dissolution in the example appear greater, lesser, or remain the same if the heat capacity of the calorimeter were taken into account? Explain your answer.
5.2 Exercise 6
How much will the temperature of a cup (180 g) of coffee at 95 °C be reduced when a 45 g silver spoon (specific heat 0.24 J/g °C) at 25 °C is placed in the coffee and the two are allowed to reach the same temperature? Assume that the coffee has the same density and specific heat as water.
5.2 Exercise 8
The temperature of the cooling water as it leaves the hot engine of an automobile is 240 °F. After it passes through the radiator it has a temperature of 175 °F. Calculate the amount of heat transferred from the engine to the surroundings by one gallon of water with a specific heat of 4.184 J/g °C.
5.2 Exercise 10
If a reaction produces 1.506 kJ of heat, which is trapped in 30.0 g of water initially at 26.5 °C in a calorimeter like that in the figure, what is the resulting temperature of the water?
5.2 Exercise 12
Dissolving 3.0 g of CaCl2(s) in 150.0 g of water in a calorimeter (the figure) at 22.4 °C causes the temperature to rise to 25.8 °C. What is the approximate amount of heat involved in the dissolution, assuming the specific heat of the resulting solution is 4.18 J/g °C? Is the reaction exothermic or endothermic?
5.2 Exercise 14
The addition of 3.15 g of Ba(OH)2·8H2O to a solution of 1.52 g of NH4SCN in 100 g of water in a calorimeter caused the temperature to fall by 3.1 °C. Assuming the specific heat of the solution and products is 4.20 J/g °C, calculate the approximate amount of heat absorbed by the reaction, which can be represented by the following equation:
Ba(OH)2·8H2O(s) + 2NH4SCN(aq) ⟶ Ba(SCN)2(aq) + 2NH3(aq) + 1…
5.2 Exercise 16
If the 3.21 g of NH4NO3 in the example were dissolved in 100.0 g of water under the same conditions, how much would the temperature change? Explain your answer.
5.2 Exercise 18
When a 0.740-g sample of trinitrotoluene (TNT), C7H5N2O6, is burned in a bomb calorimeter, the temperature increases from 23.4 °C to 26.9 °C. The heat capacity of the calorimeter is 534 J/°C, and it contains 675 mL of water. How much heat was produced by the combustion of the TNT sample?
5.2 Exercise 20
The amount of fat recommended for someone with a daily diet of 2000 Calories is 65 g. What percent of the calories in this diet would be supplied by this amount of fat if the average number of Calories for fat is
9.1 Calories/g?
5.2 Exercise 22
What is the maximum mass of carbohydrate in a 6-oz serving of diet soda that contains less than 1 Calorie per can if the average number of Calories for carbohydrates is 4.1 Calories/g?
5.2 Exercise 24
A serving of a breakfast cereal contains 3 g of protein, 18 g of carbohydrates, and 6 g of fat. What is the Calorie content of a serving of this cereal if the average number of Calories for fat is 9.1 Calories/g, for carbohydrates is 4.1 Calories/g, and for protein is 4.1 Calories/g?
Adapted from General Chemistry © 2019 Rice University. Licensed under CC BY 4.0. Sources: Chemistry 2e, Chemistry: Atoms First 2e. Imported at revision 32c7196.