Question

A sample of cold water was mixed with a sample of hot water inside a calorimeter, and the final temperature of the cold water was 40 °C. Which statement is true about the hot water in the calorimeter? It absorbed 40 joules. It absorbed 80 joules. Its final temperature was 80 °C. Its final temperature was 40 °C.

Answer 1

Answer: One technique we can use to measure the amount of heat involved in a chemical or physical process is known as calorimetry. Calorimetry is used to measure amounts of heat transferred to or from a substance. To do so, the heat is exchanged with a calibrated object (calorimeter). The change in temperature of the measuring part of the calorimeter is converted into the amount of heat (since the previous calibration was used to establish its heat capacity). The measurement of heat transfer using this approach requires the definition of a system (the substance or substances undergoing the chemical or physical change) and its surroundings (the other components of the measurement apparatus that serve to either provide heat to the system or absorb heat from the system). Knowledge of the heat capacity of the surroundings, and careful measurements of the masses of the system and surroundings and their temperatures before and after the process allows one to calculate the heat transferred as described in this section.

Explanation:

Answer 2

Answer: Option (d) is the correct answer.

Explanation:

Since it is given that temperature of hot water is 40 degree celsius. So, when cold water is added into it then it will absorb heat from the hot water and hence, temperature of cold water will become equal to 40 degree celsius.

Therefore, a thermal equilibrium will be maintained as temperature of both hot and cold water becomes equal. In thermal equilibrium, hotter body loses the heat and colder body absorbs the heat.

Therefore, we can conclude that the true statement about the hot water in the calorimeter is its final temperature was $40^{o}C$.