Question

A 10.05 gram sample of BaCl2 x H20 hydrate is heated and the resulting mass is 8.57 grams. a. What is the formula for the hydrate?b. What is the name of the hydrate?

Answer 1

Step 1: Let's calculate the quantity in moles of anhydrous barium chloride using the resulted mass after the heating divided by its molar mass (molar mass of BaCl2 is 208.23 g/mol)

so:

8.57/208.23 = 0.04 moles of BaCl2

Step 2: Now let's calculate the quantity in moles of water. But first, we need to calculate the mass of H2O. For this, we just subtract the mass before the heating by the mass after the heating. The water evaporated because of the heat.

mass of H2O = 10.05 - 8.57 = 1.48 g

Now we divide the mass by its molar mass to find the quantity in moles (molar mass of water is 18 g/mol)

1.48/18 = 0.082 moles of H2O

Step 3: Now we determine the number ratio:

0.082/0.04 = 2

So the formula is:

Answer: a. BaCl2 x 2H2O

b. barium chloride dihydrate