# What is BaCl2 * 5H2O

Chemistry help plz!!

I've tried to work out the problem below, but I got weird answer, it's not even in one of the choices. Please help me solve this problem and show me out u got it. Thank you.
A sample of a hydrate of BaCl2 with a mass of 61 grams was heated until all the water was removed. The sample was then weighed and found to have a mass of 52 grams. What is the formula for the hydrate?
(A) BaCl2 * 5H2O
(B) BaCl2 * 4H2O
(C) BaCl2 * 3H2O
(D) BaCl2 * 2H2O
(E) BaCl2 * H2O

Ivan Seeking
Staff Emeritus
Gold Member

Originally posted by gigi9
I've tried to work out the problem below, but I got weird answer, it's not even in one of the choices. Please help me solve this problem and show me out u got it. Thank you.
A sample of a hydrate of BaCl2 with a mass of 61 grams was heated until all the water was removed. The sample was then weighed and found to have a mass of 52 grams. What is the formula for the hydrate?
(A) BaCl2 * 5H2O
(B) BaCl2 * 4H2O
(C) BaCl2 * 3H2O
(D) BaCl2 * 2H2O
(E) BaCl2 * H2O

Starting with your equation: BaCl2 + MH2O

Then, N x grams per mole of (BaCl2 + MH2O) = 61 grams

N is the number of moles of the hydrate.

Where we must determine the coefficient M.

You know that you have removed 9 grams of water:

M x (N moles of H2O at [(2 X 1.008) + 15.99]grams/mol) = 9 grams

Solve for N,
N moles of BaCl2 at [137.34 + (2 X 35.45)] = 52 grams.

then M.

Last edited:
In a problem like this you figure out how many moles of **** you got.

You've got 52 of straight up BaCl2. That's 208 grams per mole, so 52/208 = 0.25 moles.

You've got 9 grams of water at 18 grams/mole, so you've got 0.5 moles H20.

So then if you can't figure out the rest you deserve that bad grade. (-;