Question

Calcium hydroxide + hydrogen chloride ------ rightarrow calcium chloride + water Ca(OH)_2 + 2 HCl rightarrow Cacl_2 + 2 H_2O How many grams of calcium chloride will be produced from 4.50 mL of a 0.166M hydrogen chloride solution? (M = moles/L)

Answer 1

Given chemical transformation

Calcium hydroxide + hydrogen chloride ----------> Calcium chloride + water

Using chemical formulae we write a balanced chemical equation as,

Ca(OH)2 + 2 HCl -----------> CaCl2 + 2 H2O

Stoichiometry of the reaction says that the chemical equivalence is as,

2 moles of HCl $\equiv$ 1 mole of CaCl2.

For given HCl solution, Volume (V) = 4.50 mL = 4.50 x 10^-3 L and molarity (M) = 0.166 M

Then number of moles of HCl = Molarity x Volume = 0.166 x 4.50 x 10^-3 = 0.747 x 10^-3 moles.

With this we write equivalence as,

If, 2 moles of HCl $\equiv$ 1 mole of CaCl2.

then, 0.747 x 10^-3 moles of HCl $\equiv$ say 'A' mole of CaCl2.

A x 2 = 0.747 x 10^-3.

A = 0.747 x 10^-3 / 2

A = 0.3735 x 10^-3 moles of CaCl2.

Molar mass of CaCl2 = 110.98 g/mol

i.e 1 mole of CaCL2 = 110.98 g

$\therefore$   0.3735 x 10^-3 moles of CaCl2. = 0.3735 x 10^-3 .x 110.98

= 41.5 x 10^-3 g of CaCl2.

= 0.0415 g of CaCl2.

0.0415 g of CaCl2 will be formed.

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