Question

The reaction of 50 mL of acid and 50 mL of base described in Example 9.5 increased the temperature of the solution by 6.9 ºC. How much would the temperature have increased if 100 mL of acid and 100 mL of base had been used in the same calorimeter starting at the same temperature of 22.0 ºC? Explain your answer.

Answer 1

Doubling the amount of acid and base in a calorimetry experiment in an ideal calorimeter results in double the heat being produced, but the temperature increase remains the same because the capacity to absorb heat is also doubled.

Step-by-step explanation:

If we double the volumes of acid and base used in a calorimetry experiment, under the assumption that the calorimeter does not absorb any heat and there is no heat exchange with the environment, the amount of heat produced by the reaction will double. However, the temperature increase will remain the same. This is because the heat capacity of the solution is directly proportional to its mass. When we double the amounts of acid and base, we are also doubling the mass of the solution, meaning it can absorb twice as much heat without changing the temperature rise observed.

For example, in Example 9.5, mixing 50.0 mL of 1.00 M HCl and 50.0 mL of 1.00 M NaOH resulted in a temperature increase of 6.9 °C. If 100 mL of each were used instead, the reaction would produce twice as much heat, but since the mass of the solution is also doubled, the temperature increase would still be 6.9 °C.