Calorimetry Assignment and Quiz

A sample of hexane (C6H14) has a mass of 0.580 g. The sample is burned in a bomb calorimeter that has a mass of 1.900 kg and a specific heat of 3.21 J/giK. What amount of heat is produced during the combustion of hexane if the temperature of the calorimeter increases by 4.542 K?

27.7 kJ

Use the specific heat values to answer the following questions. Which of the following has the smallest heat capacity? Which of the following would release the most heat upon cooling from 75°C to 50°C?

3.0g Pb 10g H2O(l)

A cube of iron (Cp = 0.450 J/g•°C) with a mass of 55.8 g is heated from 25.0°C to 49.0°C. How much heat is required for this process? Round your answer to three significant figures. A sample of tin (Cp = 0.227 J/g•°C) is placed in a freezer. Its temperature decreases from 15.0°C to −10.0°C as it releases 543 J of energy. What is the mass of the sample? Round your answer to three significant figures.

603 J 95.7g

Sodium carbonate (Na2CO3) reacts with acetic acid (CH3COOH) to form sodium acetate (NaCH3COO), carbon dioxide (CO2), and water (H2O). A chemist carries out this reaction in a bomb calorimeter. The reaction causes the temperature of a bomb calorimeter to decrease by 0.985 K. The calorimeter has a mass of 1.500 kg and a specific heat of 2.52 J/g•K. What is the heat of reaction for this system? This reaction is

-3.72 kJ endothermic

What is the specific heat of a substance if a mass of 10.0 kg increases in temperature from 10.0°C to 70.0°C when 2,520 J of heat is applied?

0.00420 J/(gi°C)

The specific heat of water is 4.18 J/(gi°C) and that of wood is 1.97 J/(gi°C). Which statement is correct?

Given equal masses, water will heat up less than wood if the same heat is added.

Which statement describes how a basic coffee cup calorimeter works?

It uses the mass and specific heat of water along with a thermometer to measure the gain or loss of energy when a substance is added.

Which units express heat capacity?

J/°C, J/K, cal/°C, cal/K

What would be the greatest difference in using an open ceramic coffee mug rather than an insulated mug with a lid as a calorimeter?

exchange of energy with the surroundings

Which statement defines the heat capacity of a sample?

the quantity of heat that is required to raise the sample's temperature by 1°C (or Kelvin)

The initial temperature of a bomb calorimeter is 28.50°C. When a chemist carries out a reaction in this calorimeter, its temperature decreases to 27.45°C. If the calorimeter has a mass of 1.400 kg and a specific heat of 3.52 J/(gi°C), how much heat is absorbed by the reaction?

5,170 J

Describe how you could determine the specific heat of a sample of a solid substance. You may assume that the substance does not react with water. In your answer, make sure to include a description of what equipment you would use and how you would interpret the data you collected.

I would use calorimetry to determine the specific heat. I would measure the mass of a sample of the substance. I would heat the substance to a known temperature. I would place the heated substance into a coffee-cup calorimeter containing a known mass of water with a known initial temperature. I would wait for the temperature to equilibrate, then calculate temperature change. I would use the temperature change of water to determine the amount of energy absorbed. I would use the amount of energy lost by substance, mass, and temperature change to calculate specific heat.

Which units express specific heat capacity?

J/(gi°C), J/(giK), cal/(gi°C), cal/(giK)

The heat capacity of a sample should be divided by which quantity to find the specific heat capacity?

mass in grams