Concentrations
The concentration of a solution indicates the amount of solute dissolved in 1L of water
Calculating concentrations
Calculate the concentration of a solution made by dissolving:
0.5 moles of sodium hydroxide in 200 mL of water.
NB - Volume MUST always be converted to L c = n / V = 0.5mol / 0.2L = 2.50 mol/L (3sf) |
2.5 mol of calcium nitrate in 3.5 L of water
c = n / V = 2.5mol / 3.5L = 0.714 mol/L (3sf) All ANSWERS MUST BE ROUNDED TO 3 SIGNIFICANT FIGURES (3sf) |
Finding the amount
What amount of solute is required to make up:
250mL of 0.001mol/L solution of sodium hydroxide
n = c x V = 0.001mol/L x 0.25L = 2.50x10^-4 mol (3sf) OR = 0.000250 mol (3sf) |
2L of 0.1mol/L hydrochloric acid solution
n = c x V = 0.1mol/L x 2L = 0.200 mol (3sf) |
20mL of a 0.75mol/L potassium permanganate solution
n = c x V = 0.75mol/L x 0.02L = 1.5x10^-2 mol (3sf) OR 0.0150 mol (3sf) |
All ANSWERS MUST BE ROUNDED TO 3 SIGNIFICANT FIGURES (3sf)
Finiding the mass
Find the mass of sodium hydroxide needed to make up 500mL of 0.01mol/L solution