Question

What is the molar mass of calcium hydroxide?

Answer 1

Step 1: Molar mass:

• The mass of 1 mole of a substance is called its molar mass.

Step 2: Formula for molar mass

• $\mathrm{Molar}\mathrm{mass}=\mathrm{The}\mathrm{atomic}\mathrm{mass}\mathrm{of}\mathrm{element}\times \mathrm{number}\mathrm{of}\mathrm{atoms}\mathrm{given}\mathrm{in}\mathrm{subscript}$

Step 3: Calculation of Molar mass of calcium hydroxide $\left(\mathrm{Ca}{\left(\mathrm{OH}\right)}_2\right)$:

$$\begin{gathered} \mathrm{Molar}\mathrm{mass}\mathrm{of}\mathrm{Ca}{\left(\mathrm{OH}\right)}_2=\mathrm{Atomic}\mathrm{mass}\mathrm{of}\mathrm{Ca}+\mathrm{Atomic}\mathrm{mass}\mathrm{of}\mathrm{O}+\mathrm{Atomic}\mathrm{mass}\mathrm{of}\mathrm{H} \\ \mathrm{Molar}\mathrm{mass}\mathrm{of}\mathrm{Ca}{\left(\mathrm{OH}\right)}_2=40.08\mathrm{g}{\mathrm{mol}}^{-1}+\left(2\times 16.00\mathrm{g}{\mathrm{mol}}^{-1}\right)+\left(2\times 1.0079\mathrm{g}{\mathrm{mol}}^{-1}\right) \\ \mathrm{Molar}\mathrm{mass}\mathrm{of}\mathrm{Ca}{\left(\mathrm{OH}\right)}_2=40.08\mathrm{g}{\mathrm{mol}}^{-1}+32\mathrm{g}{\mathrm{mol}}^{-1}+2.0158\mathrm{g}{\mathrm{mol}}^{-1}=74.095\mathrm{g}{\mathrm{mol}}^{-1} \end{gathered}$$

Thus, the molar mass of calcium hydroxide is $74.095\mathrm{g}{\mathrm{mol}}^{-1}$.