1. Solutions – Concentration Calculations Revision

2. eg 2 mol/l hydrochloric acid solution means that the solution has 2 mol of HCl dissolved in 1 litre of solution 2 mol/l concentration used to tell how much of a substance is present in a solution measured in moles per litre shortened to: mol/l

3. what to use in calculations conc mol vol volume of solution in litres moles Use this to do concentration calculations concentration in mol/l If the volume is given in cm 3 it must be changed into litres litres = cm 3 1000

4. What is the concentration when 0.5 moles of solute are dissolved in a 250 cm 3 solution of sodium chloride? using the concentration = moles volume in litres 250 1000 = 0.25 litres = 0.5 0.25 = 2 mol/l

5. How many moles of solute are dissolved in 100 cm 3 of a 0.5 mol/l solution? using the moles = concentration x volume in litres 100 1000 = 0.1 litres = 0.5 x 0.1 = 0.05 mol

6. What is the concentration when 10g of NaOH is dissolved in 750 cm 3 of solution? using the 750 1000 = 0.75 litres = 0.33 mol/l hardest type 1 st 10g of NaOH has to be changed to moles (mol calcs!!) 1 mol NaOH = 40g so 10g NaOH = 0.25 mol concentration = moles volume in litres = 0.25 0.75