Question

What is the molarity of solution containing 10% by mass of calcium hydroxide in 0.5dm^3 of solution

Answer 1

Given:

• mass percent = 10%

• Volume= 0.5 dm³ = 0.5 L

• Molar mass of Ca(OH)₂ = 40 + 32 +2 =74 g/mol

To find:

• Molarity

Solution:

Solution containing 10% by mass of calcium hydroxide means 10 g of calcium hydroxide is present in 100 g of solution.

• Mass of Ca(OH)₂ = 10g
• Molar mass of Ca(OH)₂ = 74 g/mol

$\to\sf{Moles \: of \: Ca(OH)_2= \dfrac{Mass \: of \: Ca(OH) _2}{molar mass \: of \: Ca(OH) _2}}$

$\to\sf{Moles \: of \: Ca(OH)_2= \dfrac{10}{74}}$

$\to\sf{Moles \: of \: Ca(OH)_2= 0.135}$

Now, as per the formula,

$\to\sf{Molarity= \dfrac{moles \: of \: Ca(OH) _2}{Volume \: of \: solution (L) }}$

$\to\sf{Molarity= \dfrac{0.135}{0.5}}$

$\to \boxed{\sf{Molarity= 0.27 \: molar}}$

The molarity of the solution is 0.27 molar.

Answer 2

Answer:

\mathbb{GIVEN}GIVEN

mass percent = 10%

Volume= 0.5 dm³ = 0.5 L

Molar mass of Ca(OH)₂ = 40 + 32 +2 =74 g/mol

\mathbb{TO \: FIND}TOFIND

Molarity

\mathbb{SOLUTION}SOLUTION

Solution containing 10% by mass of calcium hydroxide means 10 g of calcium hydroxide is present in 100 g of solution.

Mass of Ca(OH)₂ = 10g

Molar mass of Ca(OH)₂ = 74 g/mol

\begin{gathered}\begin{gathered}\to\tt{Moles \: of \: Ca(OH)_2= \dfrac{Mass \: of \: Ca(OH) _2}{molar mass \: of \: Ca(OH) _2}} \\\end{gathered}\end{gathered}

→MolesofCa(OH)

2

=

molarmassofCa(OH)

2

MassofCa(OH)

2

\begin{gathered}\begin{gathered}\to\tt{Moles \: of \: Ca(OH)_2= \dfrac{10}{74}} \\\end{gathered} \end{gathered}

→MolesofCa(OH)

2

=

74

10

\begin{gathered}\begin{gathered}\to\tt{Moles \: of \: Ca(OH)_2= 0.135} \\\end{gathered}\end{gathered}

→MolesofCa(OH)

2

=0.135

Now, as per the formula,

\begin{gathered}\begin{gathered}\to\tt{Molarity= \dfrac{moles \: of \: Ca(OH) _2}{Volume \: of \: solution (L) }} \\\end{gathered}\end{gathered}

→Molarity=

Volumeofsolution(L)

molesofCa(OH)

2

\begin{gathered}\begin{gathered}\to\tt{Molarity= \dfrac{0.135}{0.5}} \\\end{gathered}\end{gathered}

→Molarity=

0.5

0.135

\begin{gathered}\begin{gathered}\to {\bf{Molarity= 0.27 \: molar}} \\\end{gathered}\end{gathered}

→Molarity=0.27molar

\fbox{☛Molariry = {0.27} Molar }

☛Molariry = 0.27 Molar