Question

What is the molar concentration of solution of 162.8g of calcium hydroxide dissolved completely in 1000cm cube of distilled water (ca=40,o=16,h=1)

Answer 1

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Answer on Question # 65529 - Chemistry | General Chemistry

What is the molar concentration of solution of $162.8\mathrm{g}$ of calcium hydroxide dissolved completely in $1000\mathrm{cm}$ cube of distilled water $(\mathrm{Ca} = 40, \mathrm{O} = 16, \mathrm{H} = 1)$

Solution

$$\mathrm{m}(Ca(OH)_2) = 162.8\ \mathrm{g}$$ $$V = 1000\ \mathrm{cm}^3 = 1\ \mathrm{L}$$ $$C = \frac{n}{V}$$ $$n = \frac{m}{M}$$ $$\mathrm{M}(Ca(OH)_2) = 40 + 2 \cdot 16 + 2 \cdot 1 = 74\ \mathrm{g/mol}$$ $$n = \frac{m}{M} = \frac{162.8\ \mathrm{g}}{74\ \frac{\mathrm{g}}{\mathrm{mol}}} = 2.2\ \mathrm{mol}$$ $$C = \frac{n}{V} = \frac{2.2\ \mathrm{mol}}{1\ \mathrm{L}} = 2.2\ \mathrm{mol/L} = 2.2\ \mathrm{M}$$

Answer

The molar concentration must be $2.2\ \mathrm{mol/L}$ or $2.2\ \mathrm{M}$.