1. Starter
What are the similarities and differences between the balloons

2. Molar volume of gases
understand the term molar volume of a gas and use its values (24 dm3 and 24,000 cm3) at room temperature and pressure (rtp) in calculations.

3. Converting units
mm  cm  dm  m 1000mm  100cm  10dm  1m Divide by 10
Calculate the following:
1. 15mm in cm
dm in mm
3. 180dm in m.
m in mm
Answers
1.5cm
75mm
18m
13500mm

4. Converting units
mm2  cm2  dm2  m2 1,000,000mm2  10000cm2  100dm2  1m2 Divide by 100
Calculate the following:
1. 15mm2 in cm2
mm2 in dm2
3. 180dm2 in m2
m in mm2
Answers
0.15cm2
7.5x10-5dm2
1.8m2
13.5x106mm2

5. Converting units mm3  cm3  dm3  m3
Divide by 1000
Calculate the following:
1. 15mm3 in cm3
mm3 in dm3
3. 180dm3 in m3
m3 in mm3
Answers
0.015cm3
7.5x10-7dm3
0.18m3
1.35x1010mm3

6. Moles of gases
Equal volumes of gases at the same temperature and pressure contain equal number of particles.
No matter what the size of the gas particle, large empty space exists between individual particles of gas.

7. Calculating Molar Volume
Avagadro’s other rule
Calculating Molar Volume
Avagadro’s other rule
1 mole of any gas at room temperature (25oC) and room pressure (1 atm) occupies a volume of 24 dm3.
This is known as the molar volume of a gas.

8. The triangle’s

9. Work Out What is the volume of.. A- 3 moles of oxygen
B- 2.5 moles of hydrogen
C moles of tetrafluoroethane
D- 13 moles of methane
E- 7.2 moles of neon

10. Answers
72dm3
60dm3
0.24dm3
312dm3
172.8dm3

11. How many moles? 48 dm3 of helium 0.96 dm3 of nitrogen
1440 dm3 of water vapour
1 dm3 of argon
2.4 cm3 of chlorofluoroethane

12. Answers
2mol
0.04mol
60mol
mol
1x10-4mol

13. Can you work this one out?
22g of a hydrocarbon gas had a volume of 6 dm3.
Calculate its molecular mass.
Another hydrocarbon sample has a mass of 0.28g and a volume of 0.24 dm3.

14. answer 6/24 = 0.25moles 22/0.25 = 88 Mr = 88 0.24/24 = 0.01mol
0.28/0.01 = 28
Mr = 28

15. Calculating molar volumes
A GAS SYRINGE is used to collect gases during reactions to allow molar gas calculations to be performed

16. Method Set up equipment as shown in the diagram
Measure 100cm3 of 1M HCl
Using the sandpaper sand down the magnesium strips until they are shiny and then measure their mass
Add the magnesium strips to the HCl
Collect the gas using gas syringe
Calculate the number of moles of HCL and magnesium used and also the hydrogen gas produced

17. Calculating moles produced
Calculating Molar Volume
You need a balanced equation to calculate the volume occupied by a gas.
Eg How much hydrogen is needed to obtain 2.54g of copper by reducing copper oxide.
H2 + CuO Cu + H2O

18. How to do it Moles = mass/relative mass = 2.54/63.5 = 0.04 moles
Use equation to work out number of moles hydrogen needed.
1 mol Cu reacts with 1 mol H2
So 0.04 mol reacts with 0.04 mol.
0.04 mol has a volume of – 0.04 x 24 = 0.96 dm3

19. Work out
Calculate the volume of nitrogen dioxide that is produced when 0.5 dm3 of nitrogen reacts with oxygen under RTP.
N2(g) + 2O2(g) → 2NO2(g)
Answer
1dm3

20. MgCO3(s) + 2HCl(aq)MgCl2(aq) + H2O(l) +CO2(g)
Magnesium carbonate is an ingredient in some antacid medicines. When it is added to stomach acid the following reaction takes place:
MgCO3(s) + 2HCl(aq)MgCl2(aq) + H2O(l) +CO2(g)
What mass of magnesium carbonate reacts to form 6 dm3 of carbon dioxide? (relative atomic mass of magnesium = 24, carbon = 12, oxygen = 16)
Answer: 21g

21. Challenge
Zinc reacts with sulfuric acid to produce hydrogen gas and a solution of zinc sulfate.
Write a balanced equation for the reaction.
Calculate the volume of hydrogen produced at RTP when 32.5g of zinc reacts completely with sulfuric acid.

22. Answers Zn + H2SO4  H2 + ZnSO4 Moles of zinc  32.5/65  0.5mol
Ratio 1:1 so 0.5mol Hydrogen
0.5*24  12dm3