Question

which statement describes how a basic coffee cup calorimeter works?

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

it measures the density of a substance given the mass, specific heat, and temperature of water in a cup of known size.

it measures the mass of a substance given the specific heat and temperature of water in a cup of known size.

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.

Explanation:

Identify the purpose of a coffee cup calorimeter

A coffee cup calorimeter is a constant-pressure calorimeter used to measure the heat exchange (gain or loss of energy) during a chemical or physical process in solution.

Analyze the required measurements

To calculate heat transfer \(q = m c \Delta T\), we need the mass of the water (\(m\)), the specific heat capacity of the water (\(c\)), and the change in temperature (\(\Delta T\)), which is measured using a thermometer.

Evaluate the options

• Option 1 mentions a pressure gauge, which is incorrect for a simple constant-pressure coffee cup calorimeter.
• Options 2 and 3 state it measures density or mass, which are not the direct quantities determined by operating the calorimeter.
• Option 4 correctly states it uses the mass and specific heat of water along with a thermometer to measure the gain or loss of energy.

Answer:

• It uses the mass and specific heat of water along with a pressure gauge to measure the gain or loss of energy when a substance is added.
• It measures the density of a substance given the mass, specific heat, and temperature of water in a cup of known size.
• It measures the mass of a substance given the specific heat and temperature of water in a cup of known size.
• 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. (Correct answer)