Question

What is the percent water in the compound barium chloride dihydrate $?$

Answer 1

Hint : Here we have to divide the mass of the water lost by the mass of hydrate and multiply by $100$ . The actual percent water can be calculated from the formula of the hydrate by dividing the mass of water in one mole of the hydrate by the molar mass of the hydrate and multiplying by $100$ .

Complete Step By Step Answer:
Barium chloride dihydrate is an ionic compound that contains water molecules in its crystal structure i.e., a hydrate. The water that's part of the solid crystal structure is called water of crystallisation. In the case of barium chloride dihydrate, you get two moles of water of crystallization for every one mole of hydrate. In other words, if you were to drive the water of crystallization off by heating the hydrate, you would be left with one mole of anhydrous barium chloride, $BaC{l_2}$ ,
for every one mole of hydrate.
To find the hydrate's percent composition of water in barium chloride dihydrate, use the mass of one mole of hydrate and of two moles of water.
Barium chloride dihydrate has a molar mass of $244.26\;g\;mo{l^{ - 1}}$ , which means that one mole of dihydrate $244.26\;g$ .
since one mole of hydrate contains two moles of water, and since water has a molar mass $18.015\;g\;mo{l^{ - 1}}$ . Hence, we get $2 \times 18.015\;g\;mo{l^{ - 1}}$ of water for every $244.26\;g$ of hydrate.
Hence, the percent composition of water is
$\dfrac{{2 \times 18.015\;g}}{{244.26\;g}} \times 100 = 14.751\%$
This means that you get $14.751\;g$ of water for every $100\;g$ of $BaC{l_2} \cdot 2{H_2}O$ .

Note :
Note that barium chloride is an anion and it has a negative charge. Barium chloride is mainly used in the purification of brine solution in caustic chlorine plants in industry and also in the manufacture of heat treatment slats, case hardening of steel, in the manufacture of other barium slats.