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A researcher studying the extraction of alumina from bauxite requires 100mL of a sodium hydroxide solution of pH 12.0 When the stock solution was checked it was found to have a pH of 11.7. What mass of sodium hydroxide must be added to increase the pH of this solution to 12.0? Assume the volume of the solution does not change with the addition of the solid.
A researcher studying the extraction of alumina from bauxite requires 100mL of a sodium hydroxide solution of pH 12.0 When the stock solution was checked it was found to have a pH of 11.7. What mass of sodium hydroxide must be added to increase the pH of this solution to 12.0? Assume the volume of the solution does not change with the addition of the solid.
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If pH = 12.0, then pOH = 2.00
[OH-] = 10^-2
Molar mass NaOH = 40g/mol
concentration of NaOH solution = 40*10^-2 g/litre = 0.40g/litre
Mass NaOH in 100mL of solution = 0.040g
If pH = 11.7 , then pOH = 2.30
[OH-] = 10^-2.3
Concentration NaOH in 1 liter of solution = 40*10^-2.3 = 0.20g/L
Mass NaOH in 100mL = 0.02g
In order to increase the pH from 11.7 to 12.0, you add 0.02g NaOH to the 100mL solution.
[OH-] = 10^-2
Molar mass NaOH = 40g/mol
concentration of NaOH solution = 40*10^-2 g/litre = 0.40g/litre
Mass NaOH in 100mL of solution = 0.040g
If pH = 11.7 , then pOH = 2.30
[OH-] = 10^-2.3
Concentration NaOH in 1 liter of solution = 40*10^-2.3 = 0.20g/L
Mass NaOH in 100mL = 0.02g
In order to increase the pH from 11.7 to 12.0, you add 0.02g NaOH to the 100mL solution.