How do you calculate the concentration of sodium hydroxide?

Calculate the molar concentration of equivalent of 50% solution of sodium hydroxide?

• Density of solution is 1.53g/ml

• Answer:

  If you work on the basis that 50% NaOH solution means 50g NaOH dissolved in 100mL of final solution - this is a 50%m/v solution . Mass of NaOH dissolved in 1.0L solution = 500g NaOH molar mass NaOH = 40g/mol Mol NaOH in 500g = 500/40 = 12.5 mol NaOH dissolved in 1.0L solution. Molarity = 12.5mol / L or 12.5M If you work on the basis that 50% NaOH solution means 50g NaOH dissolved in 100g of solution : This is a 50%m/m solution Volume of this solution = Mass / density Volume = 100g / 1.53 Volume = 65.36 mL You have 50g NaOH dissolved in 65.36mL solution. Mass dissolved in 1.0L solution = 1000/65.36*50 = 765g NaOH Moles of NaOH = 765/40 = 19.125 mol NaOH dissolved in 1.0L solution . Molarity = 19.125 mol / L OR 19.125M When quoting % concentrations it is necessary to state whether you have an m/v or an m/m solution . Because the question contains details of density I guess that the second solution is what is required.