Part -1:

1. We keep the drying oven at 105°C to evaporate water from the wet sand. You heat the evaporating dish over a Bunsen burner with a flame temperature of 900-1200°C to evaporate water from the dissolved salt. Contact with water at 68°C can produce a serious scald in one second. Describe precautions you should take to avoid burning yourself in today's experiment.

2. Describe the difference between a pure substance and a mixture.

3. A student found a 10.630-g mixture of salt, sand and iron to contain 4.813 g of iron and 3.507 g of sand. Calculate the mass percentages of iron, sand and salt in the mixture.

Part -2:

1. Which of the following processes requires more heat energy?

a. raising the temperature of 100. g of water by 10.0 °C

b. raising the temperature of 100. g of water by 50.0 °C

2. Which of the following processes requires more heat energy?

a. raising the temperature of 100. g of water by 10.0 °C

b. raising the temperature of 50. g of water by 10.0 °C?

3. Which of the following processes requires more heat energy?

a. raising the temperature of 100. g of water by 10.0 °C

b. raising the temperature of 100. g of aluminum by 10.0 °C?

Part -3:

1. Explain why you placed the watch glass over the evaporating dish in the salt-recovery set-up.

2. Explain why you needed to cool the recovered sand and salt to room temperature before determining their masses.

3. Suppose that, unknown to you, the sand still held some moisture after its time in the oven. Describe how this would affect your calculated mass percentage of sand.

4. Define the technical term specific heat.

5. Calculate the quantity of heat absorbed by 30.0 g of water when its temperature is raised to 67.9 °C from 24.3 °C.

6. Determine the temperature change created in 30.0 of solid gold by the addition of the same amount of heat as calculated in #5.

7. Explain why the temperature change for gold is so different from the temperature change of water.