Question

Calculate the molarity when 135 g of KCl is dissolved to make a 2.50 L solution. Round to two significant digits.

Answer 1

0.72 mol/L

Step-by-step explanation:

`\textrm{Molarity of a solution}=\frac{\textrm{Number of moles of solvent}}{\textrm{Volume of solution in Liters}}`

We are given a
`2.50L` solution which contains
`135g` of
`KCl`.

To calculate number of moles of
`KCl` present, we need to find it's molar mass from charts. Molar Mass of
`KCl` is known to be
`74.55(g)/(Mol)`.

Number of moles of
`KCl` present =
`\frac{\textrm{Given weight}}{\textrm{Molar Mass}}\textrm{ = }(135g)/(74.55(g)/(Mol))\textrm{ = }1.81087mol`

Molarity =
`(1.81087mol)/(2.50L)=0.7243(mol)/(L)`

∴ Molarity of given
`KCl` solution =
`0.72(mol)/(L)`