It is assumed that you covered the basics of concentration at GCSE. Essentially, you need to be able to work out the concentration of a solution both in mol dm-3 and in g dm-3.
Remember that the volume is always per dm3 (dm-3) and 1000 cm3 = 1 dm3 so inevitably you will have to convert cm3 into dm3.
Concentration (mol dm-3) = no. of moles (mol) / volume (dm3)
Practice questions
1. How many moles of solute are there in …
(a) 100 cm3 of 0.2 mol dm-3 KCl?
(b). 25 cm3 of 0.6 mol dm-3 NaOH?
2. Work out the concentration of …
(a) 0.5 moles of CuCl2 dissolved in 0.1 dm3 of water
(b) 0.3 moles of Na2SO4 dissolved in 0.05 dm3 water
(c) 1.2 moles of HI dissolved in 40 cm3 water
3. Work out the concentration of …
(a) 8g of NaOH dissolved in 0.3 dm3 water
(b) 24g of MgCl2 dissolved in 60 cm3 water
4. What mass of solute is needed to make up …
(a) 250cm3 of a 2 mol dm-3 solution of NaBr
(b) 30cm3 of a 0.4 mol dm-3 solution of CuSO4・5H2O
