Question

A 236.4 mL sample of water contains 0.0294 g of NaCl. Calculate the concentration in ppm.

concentration = ___ ppm

Answer 1

Ans. ppm = parts per million. 1 million = 10⁶

1 ppm means 1 part of solute in 10⁶ parts of the solution.

Assuming, 1gram = 1 ml           [i.e. density of water]

1 gram in 10⁶ mL is 1 ppm.

or, 10⁶ mL = 10³ L ; so, 1 gram in 1000 L is also 1 ppm.

Also, 1 gram = 1000 mg

Now, 1000mg in 1000L is 1 ppm. Or, 1 mg in 1L is 1 ppm.

It can be expressed in so many ways.

Given, 236.4 mL water has 0.0294 g NaCl.

Amount of NaCl in 1000 mL (= 1L) = (0.0294 / 236.4) x 1000 = 0.1243654822335025 gra                                                                                                       = 124.36 mg

That is, concentration of NaCl = 124.36 mg in 1 L

Thus, it’s 124.36 ppm.