Question

A 4.00 gram sample of a solution of sodium chloride in water was heated until all the water had evaporated. The sodium chloride that remained weighed 1.22 grams. Calculate the percentage of water in the original 4.00 grams of solution.

Answer 1

Answer: The mass percent of water in the original sample is 69.5 %

Explanation:

We are given:

Mass of NaCl remained after heating = 1.22 grams

Mass of the sample = 4.00 grams

Mass of water evaporated = Mass of sample - Mass of NaCl remained

Mass of water evaporated = (4.00 - 1.22) g = 2.78 grams

To calculate the mass percentage of water in the sample, we use the equation:

$\text{Mass percent of water}=\frac{\text{Mass of water}}{\text{Mass of sample}}\times 100$

Mass of water = 2.78 g

Mass of sample = 4.00 g

Putting values in above equation, we get:

$\text{Mass percent of water}=\frac{2.78g}{4.00g}\times 100=69.5\%$

Hence, the mass percent of water in the original sample is 69.5 %