1. Calculate the amount of substance in moles, using gas volumes
24/04/2017
Moles and gas volumes
Calculate the amount of substance in moles, using gas volumes

2. Avogadro’s Law
Equal volumes of gases at the same temperature and pressure contain equal numbers of molecules
i.e. 100cm3 of hydrogen at some temperature and pressure contains exactly the same number of molecules as 100cm3 of carbon dioxide

3. One mole of different gases
Note the same volume of each gas has a different mass

4. CH4(g) + 2O2(g)  CO2(g) + 2H2O(l)
Example
CH4(g) + 2O2(g)  CO2(g) + 2H2O(l)
The equation says you need twice as many molecules of oxygen as you do of methane. According to Avogadro’s Law, this means you will need twice the volume of oxygen as of methane.
So, if you have to burn 1 litre of methane, you will need 2 litres of oxygen.
You should also produce 1 litre of carbon dioxide
Because water is a liquid, we don’t know how much of that we get

5. Units of volume
Note:
1 litre = 1dm3 = 1000cm3
n = V/24(dm3)
Thi notes

6. Problems Take the molar volume to be 24.0dm3 at rtp.
a) Calculate the mass of 200cm3 of chlorine gas (Cl2) at rtp
b) Calculate the density of argon (Ar) at rtp.
c) Calculate the volume occupied by 0.16g of oxygen (O2) at rtp.
d) If a gas has a density of 1.42g dm-3 at rtp, calculate the mass of 1 mole of the gas