Question

Write down the concentration of the following solution in g/L and mol/L.

2 g NaOH in 50 ml solution

Answer 1

Given:

Weight in grams = 2g

Volume in litres = 50 mL = 0.05L (1 mL = 1/1000L)

Molecular mass of NaOH = 23 + 16 + 1 = 40 g/mol

Concentration in `"g"/"L" = (2"g")/(0.5"L")`

Concentration in = 40 g/L

No. of Moles(n) = `"weight"/"molecular mas"`

= `(2"g")/(40  "g/mol")`

= 0.05 mol

Concentration in `"mol"/"L" = "no. of mole"/"Volume in L"`

Concentration in `"mol"/"L" = (0.05  "mole")/(0.05 "L")`

Concentration in mol/L = 1mol/L

Thus, Concentration in g/L is 40g/L and Concentration in mol/L is 1mol/L.