C3 Calculation Practice Number of Moles (M) = Mass (g) / Molar Mass Mass conc. (g/dm3) = Mass (g) / Volume (dm3) Mole conc. (mol/dm3) = Moles (M) / Volume (dm3) Mole conc. (mol/dm3) = Mass conc . (g/dm3) / Volume (dm3) Number of Moles (M) = Volume (dm3) / 24 Challenge: Write all the equations needed for C3 chemistry on your tables. You must add units!

x Units Mass = Moles = Molar mass = Mass Moles Molar mass (Ar or Mr) YOU MUST KNOW THIS Units Mass = Moles = Molar mass = Mass Molar mass (Ar or Mr) Moles x

Practice Worked example: How many moles are there in 32g of carbon? Rearrange Worked example: How many moles are there in 32g of carbon? Moles = mass / molar mass Moles = 32 / 12 Moles = 2.67 Your turn: How many moles are there in 430g of potassium? Your turn: What is the mass of 7 Moles of iodine?

x Units Mass = Mass conc.= Volume = Mass Mass conc. Volume YOU MUST KNOW THIS Units Mass = Mass conc.= Volume = Mass Mass conc. x Volume

Mass conc = mass / volume Practice Rearrange Worked example: What is the mass conc. when 35g of lithium is dissolved in 2.3 dm3 of water? Mass conc = mass / volume Mass conc = 35 / 2.3 Mass conc = 15.2 g/dm3 Your turn: What is the mass conc. when 67g of KCl is dissolved in 20 dm3 of water? Your turn: What is the mass if mass conc. is 2.7 g/dm3 and the volume of water is 20 dm3?

x Units Moles = Mole conc.= Volume = Moles Mole conc. Volume YOU MUST KNOW THIS Units Moles = Mole conc.= Volume = Moles Mole conc. x Volume

Practice Worked example: Rearrange Worked example: What is the mole conc when 2M of NaCl are dissolved in 7 dm3 of water? Mole conc = mole / volume Mole conc = 2 / 7 Mole conc = 0.29 mol/dm3 Your turn: What is the mole conc when 5M of KCl are dissolved in 13 dm3 of water? Your turn: What is the volume if mole conc. Is 3.3 mol/dm3 and the number of moles is 12M?

x Units Mass conc. = Mole conc.= Molar mass= Mass conc. Molar mass YOU MUST KNOW THIS Units Mass conc. = Mole conc.= Molar mass= Mass conc. Molar mass (Ar or Mr) Mole conc. x

Practice Worked example: Rearrange Worked example: What is the mass conc. of 2.4 mol/dm3 of NaCl? Mass conc. = mole conc. x molar mass Mass conc. = 2.4 x 58.5 Mass conc. = 140.4 g/dm3 Your turn: What is the mass conc. of 5 mol/dm3 of KCl? Your turn: What is the molar mass of a salt which has a mole conc. of 4.4 mol/dm3 and a mass conc of 28.1 g/dm3?

What was the concentration of the sodium hydroxide? Titration Practice Worked example: In a titration, 25 cm3 of 2.75 mol dm-3 HCl reacted with 20 cm3 of NaOH. What was the concentration of the sodium hydroxide? NaOH + HCl  NaCl + H2O Your turn: In a titration, 27cm3 of 0.5 mol dm-3 sulphuric acid, H2SO4, reacted with 23 cm3 of KOH. What was the concentration of the potassium hydroxide? Your turn: In a titration, 21 cm3 of 2.0 mol dm-3 nitric acid, HNO3, reacted with 22 cm3 of NaOH. What was the concentration of the sodium hydroxide? NaOH M: 0.06875M C: 3.44 mol/dm3 V: 0.02 dm3 HCl M: 0.06875M C: 2.75 mol/dm3 V: 0.025 dm3

YOU MUST KNOW THIS Units Volume= Moles= 24 Volume Moles x 24

Practice type 1 Worked example: What is the volume of 5M of hydrogen? Rearrange Worked example: What is the volume of 5M of hydrogen? Volume = moles x 24 Volume = 5 x 24 Volume = 120 dm3 Your turn: What is the volume of 7M of F2? Your turn: What is the number of moles for 23dm3 of Cl2?

Practice type 2 Worked example: What is the volume of 5.6g of hydrogen? Step 1 – calculate moles: 5.6/2 = 2.8M Step 2 – Calculate volume: 2.8 x 24 = 67.3 dm3 Your turn: What is the volume of 7g of CO2? Your turn: 18g of a hydrocarbon gas had a volume of 12.4 dm3. Calculate its molecular mass

To convert masses of gases into volume. If NO2 has a mass of 78g. What is its volume at RTP? 2Kg of water vapour is produced in an experiment. What is the volume of water vapour produced?

NOTE: To convert cm3 to dm3, divide by 1,000. Volumes in reactions. Hydrogen gas reacts with oxygen gas to make water vapour. If 40 dm3 of hydrogen gas is burned with excess oxygen, what volume of water vapour is produced? Write out the balanced equation. Calculate the mass of gas by doing the theoretical yield calculation. Use the equation to convert the mass into a volume. NOTE: To convert cm3 to dm3, divide by 1,000.

Practice type 3 Worked example: 2H2 + O2 -> 2H2O (216/36) x 24 = Hydrogen gas reacts with oxygen gas to make water vapour. If 24g of hydrogen gas is burned what volume of water vapour is produced? 2H2 + O2 -> 2H2O (216/36) x 24 = 6 x 24 = 144dm3 Your turn: K+H2O -> KOH+H2 Balance the equation. What volume of hydrogen in dm3 is formed when 25g of K is used? Your turn: Na+HCl -> NaCl+H2 What volume of hydrogen in dm3 is formed when 267g of Na is used? 4g 1g 24g 36g 9g 216g / 4 / 4 x24 x24

Moles dm3 cm3 Titration Filtration Avagadro’s number RTP Flame test Homologous series OH- oxidation OH Mass change Reduction Ions Acidify Elements COOCH2 COOH Hard water

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