When 1 g of a salt is dissolved in 50.0 g of water, the temperature increases by 2.5ºC. Which of the following changes will cause the temperature to increase by about 5ºC?

Question

When 1 g of a salt is dissolved in 50.0 g of water, the temperature increases by 2.5ºC. Which of the following changes will cause the temperature to increase by about 5ºC?

a. Doubling the amount of salt to 2 g and doubling the amount of water to 100 g

b. Doubling the amount of water to 100 g for the same amount of salt

c. Halving the amount of salt to 0.5 g for the same amount of water

d. Doubling the amount of salt to 2 g for the same amount of water

Answer 1

The temperature change in the water upon dissolving a salt is dependent on the ∆Hsoln for that solute (salt). Thus, the greater the mass of salt that is dissolved, the greater will be the change in temperature. This makes choice (d) the most appropriate answer.