Compare mass of pure naoh in each of the aqueous solution 50g of 40%(w/w) naoh
Answers
Solution: 50g of a 40% by weight solution: 100g of the solution contains 40g NaOH and 60g H2O 50g of this solution contains 20g NaOH and 30g water.
Hence the answer: In order to calculate molarity you must consider the density of the solution: Data sheet for NaOH solution commonly available which contains the following information .
Obviously You cannot merely assume the density of the solution is 1g/ml considering pure water only.
From density table , 40% w/w NaOH solution has density = 1.4300 g/ml.
The molarity of the solution can be calculated as follows: Take 1.00L of caustic solution solution: Mass of this litre of solution = 1,430g :There is 40% NaOH in the solution : So NaOH contents is :40/100*1430 = 572g NaOH :Molar mass NaOH = 40g/mol :Mol NaOH in 572g = 572/40 = 14.3 mol :You have 14.3 mol NaOH dissolved in 1.00L solution. Hence the answer:Molarity = 14.3M