Question

You start with 1.208 g of hydrated salt that is 50% water (it does not decompose under high heat) in a dish that weighs 28.183 g. After heating to a constant mass, the dish and dried salt weigh 28.400 g. Which of the following statements best fits the given situation?

A) The dish gained weight during the heating process.
B) You successfully removed all the water from the sample.
C) The hydrated salt decomposed under high heat.
D) You did not drive off all the water from the sample.

Answer 1

Option B) You successfully removed all the water from the sample is correct. The weight of the dish and dry salt after heating is less than the calculated weight, indicating that all the water was removed from the hydrated salt.

Step-by-step explanation:

The situation described involves a hydrated salt and the process of heating it to remove water. Initially, the dish with hydrated salt has a mass of 1.208 g + 28.183 g = 29.391 g. The goal is to remove the water, which should leave behind the anhydrous (dry) salt. After heating, the total mass is 28.400 g. To find out if all water was removed, let's compare the mass before and after heating.

Total mass before heating: 29.391 g (dish + hydrated salt)
Total mass after heating: 28.400 g (dish + anhydrous salt)

The mass of the hydrated salt at the start was 1.208 g, which was 50% water, meaning 0.604 g was water. The remaining 0.604 g was the anhydrous salt. After heating, the weight of the dish and dry salt was 28.400 g. Subtracting the dish's weight (28.183 g), we get 0.217 g, which is less than 0.604 g we expected for the anhydrous salt.
Therefore, the answer is B) You successfully removed all the water from the sample, as the weight of the anhydrous salt should be less than the original hydrated salt minus the water content.