Question

If a reaction causes 20.0 mL of water to decrease temperature by

4.72 oC at constant pressure, what would be the change in
temperature if 40.0 mL of water were used instead? Assume change in
enthalpy of the reaction remains the same.

Answer 1

Doubling the volume of water from 20.0 mL to 40.0 mL for the same reaction would halve the temperature change from 4.72°C to 2.36°C, assuming the change in enthalpy remains the same.

Step-by-step explanation:

If a reaction causes a 20.0 mL of water to decrease its temperature by 4.72°C at constant pressure, and assuming the change in enthalpy of the reaction remains the same, using 40.0 mL of water would result in a two-fold increase in the mass of the water, leading to a two-fold decrease in the temperature change. Therefore, if 20.0 mL of water results in a 4.72°C decrease in temperature, 40.0 mL would lead to a 4.72°C / 2 = 2.36°C decrease in temperature. This is based on the premise that the heat capacity and mass of water are approximately equal, so doubling the mass of water halves the temperature change for the same amount of heat transfer.