1. 1. How can we work out the formula mass of a chemical? 2.What is a mole? 3.What is the formula mass of Mg(NO 3 ) 2 4.Calculate the number of moles of 5.6g of CO 5.Calculate the mass of 0.25 mole of NaCl

2. 1.Add up the atomic mass of all the elements present in the molecule 2.A mole is the Avogadro number of particles (atoms, molecules, formulae, ions or electrons) in a substance 3.148 4.0.2moles 5.14.625g

3. Learning Outcomes 1.27 carry out mole calculations using volumes and molar concentrations. Key words: solute, solvent, solution, concentration, volume, dm 3

4. The concentration of a solution is usually expressed as the amount of solute (mol) dissolved in a given volume (dm 3 ) of solution. mol Concentration (mol dm -3 ) = _________________ volume (dm 3 ) CONCENTRATION= number of MOL present in 1L or 1dm 3 of a given solution. Sometimes mol dm -3 is shown as M; molar concentration or MOLARITY. 1M; 1mol dm -3, 2M; 2mol dm -3 and so on…

5. K = 39; Mn = 55; O = 16 K = 39 Mn = 55 O = 16 x 4 = 64 = 158 g mol -1 1. Calculate the mass in grams of 1 mole of solid potassium permanganate (KMnO 4 )

6. If we dissolve 158g of KMnO4 in 1dm 3 of water (litre) we would make a solution of concentration 1mol dm -3 solvent solute solution

7. 1.316g of KMnO 4 in 1Litre of water 2.79g of KMnO 4 in 1Litre of water 3.79g of KMnO 4 in 500mL of water What would be the concentration of the following solutions? Extension: a solution of potassium hydroxide has a concentration on 0.5 mol dm -3. How many mol are there in a 25 cm 3 sample of the solution? 1.2M 2.0.5M 3.1M

8. A solution of potassium hydroxide has a concentration on 0.5 mol dm -3. How many mol are there in a 25 cm 3 sample of the solution? Since concentration= nos. of mole in 1dm3 of solution. Need to convert dm 3 to cm 3 1dm 3 = 1000 cm 3 0.5 mol dm -3 = 0.5 mol in 1000 cm 3 of solution Therefore 25cm 3 of this solution will contain 0.5 mol dm -3 _______________ × 25 mol = 0.0125 mol 1000 cm 3

9. Calculate the mass of substance required to give a concentration on 0.05 mol dm -3 in 25 cm3 solution of sodium hydroxide. 1.Find the number of moles of sodium hydroxide using the formula( you need to rearrange it). Mol = concentration (mol dm -3 ) × volume (dm 3 ) Convert cm 3 to dm 3 = 25/1000 = 0.025 dm 3 Mol= ? Concentration = 0.05 mol dm -3 Volume = 0.025 dm 3 0.05 × 0.025 = 1.25 × 10 -3 mol

10. 2. Calculate mass (you need to rearrange formula). Mass (g) = mol × formula mass (g mol-1) Mass= ? Mol= 1.25 ×10 -3 Formula mass 40 g mol-1 1.25 × 10 -3 × 40 = 0.05 g

11. Calculate the concentration which results when 0.02 g of potassium chloride (KCl) is dissolved in 50 cm 3 of water. 1.Calculate number of moles in 0.02g. 2.7 ×10 -4 mol mol Concentration = ______________ = volume (dm3) 2. Calculate concentration using formula. 5.4 ×10 -3 mol dm-3

12. 1.Calculate the concentration of the following. a. 0.02 g of NaCl dissolved in 15 cm 3 of water. b. 0.45 g of potassium hydroxide dissolved in 50cm 3 of water. c. 2.5 g of MgSO 4 in 2 dm 3 of water. d. 0.65 g of calcium chloride in 25 cm 3 of water. e. 3 g of lithium hydroxide in 125 mL of water. f. 1.23 g of iron (II) sulfate dissolved in 124.5 cm 3 of water. g. 9.75 mg of NaOH in 25cm3 of water.

13. a)0.2M b)0.16M c)0.01M d)0.234M e)1M f)0.6M g)9.75M

14. 2. Calculate the mass in grams of substance in the following solutions. a.25cm 3 of 0.01 mol dm -3 solution of sodium chloride. b.70 cm 3 of 0.25 mol dm -3 solution of lithium sulfate. c.34. 5 cm 3 of 0.067 mol dm -3 solution of copper (II) chloride

15. a)0.015g b)1.925g c)0.31g

16. Go to each of the ten stations and answer the questions