Question

How many grams of calcium chloride would you need to make 1 L of solution containing 5 ppm calcium (Ca)?

Answer 1

Step-by-step explanation:

The given data is as follows.

Volume = 1 L, Concentration of Ca = 5 ppm or 5 mg/L

As 1 mg = 0.001 g so, 5 mg /L will be equal to 0.005 g/l. Molar mass of calcium is 40.078 g/mol.

Hence, calculate molarity of calcium as follows.

Molarity of Ca =
`\frac{\text{given concentration}}{\text{molar mass}}`

=
`(0.005 g/l)/(40.078 g/mol)`

Molarity of Ca =
`1.25 * 10^(-4) M`

Hence, molarity of
`CaCl_(2)` is
`1.25 * 10^(-4) M`. Since, volume is same so, moles of calcium chloride will be
`1.25 * 10^(-4) mol`.

Thus, we can conclude that mass of
`CaCl_(2)` will be as follows.

`1.25 * 10^(-4) * 110.984` (molar mass of
`CaCl_(2)` = 110.984 g/mol)

= 0.0138 g

Thus, we can conclude that mass of
`CaCl_(2)` is 0.0138 g.