A 1.994-g sample of gypsum, a hydrated salt of calcium sulfate, CaSO_4_, is heated at a temperture greater than 170 degrees C in a crucible until a constant mass is reached. The mass of the anhydrous CaSO_4_ salt is 1.577g. What is the mass percent of water in the hydrated calcium sulfate salt?

mass water lost = 1.994 - 1.577 = ?? grams.

%water = (mass water/mass sample)*100 = ??

To find the mass percent of water in the hydrated calcium sulfate salt, we need to determine the mass of water lost during the heating process.

Given:
- Mass of the hydrated salt (gypsum) = 1.994 g
- Mass of the anhydrous salt (CaSO_4) = 1.577 g

To calculate the mass percent of water, follow these steps:

Step 1: Determine the mass of water lost
Mass of water lost = Mass of the hydrated salt - Mass of the anhydrous salt
Mass of water lost = 1.994 g - 1.577 g
Mass of water lost = 0.417 g

Step 2: Calculate the mass percent of water
Mass percent of water = (Mass of water lost / Mass of the hydrated salt) x 100%
Mass percent of water = (0.417 g / 1.994 g) x 100%
Mass percent of water ≈ 20.93%

Therefore, the mass percent of water in the hydrated calcium sulfate salt is approximately 20.93%.