Question

Calculate the percentage of water of hydration in barium chloride crystals (the atomic weight of Ba is about 137.4 g/mol)?

Answer 1

14.75%

Explanation:

You'll need to start off by knowing the formula of the barium chloride crystals, which is barium chloride dihydrate, `BaCl_2 *2H_2O`. From the formula, you'll notice that there are 2 moles of `H_2O` for every mole of the hydrate, `BaCl_2 *2H_2O`.

When the 1 mole of hydrate crystals are heated, you will be left with 1 mole of the anhydrous crystal (`BaCl_2`) and 2 moles of `H_2O`, like this:

`BaCl_2 *2H_2O -> BaCl_2 + 2 H_2O`

To calculate the percentage of water of hydration, we'll need to find the molar mass of water (`H_2O`) and hydrate crystal (`BaCl_2 *2H_2O`).

`"molar mass " H_2O = 2(1.01) + 16.00 = 18.02 " g/mol"`

`"molar mass " BaCl_2 *2H_2O = 137.4 + 2(35.45) + 2[2(1.01) + 16.00] = 244.34 " g/mol"`

We can then proceed to calculating the percentage of water of hydration in barium chloride crystals:
`"Percentage of water of hydration" =(2 xx 18.02 ) / (244.34)*100%=14.75%`