1. Density
of a Gas at
STP
Lesson # 4

2. 1. Calculate the density of N2 at STP. Calculate
Density = grams
litre
Assume that you
have 1 mole of N2

3. 1. Calculate the density of N2 at STP. Calculate
Density = grams
litre
28.0 g =
Assume that you
have 1 mole of N2

4. 1. Calculate the density of N2 at STP. Calculate
Density = grams
litre
28.0 g =
22.4 L
Assume that you
have 1 mole of N2

5. 1. Calculate the density of N2 at STP. Calculate
Density = grams
litre
28.0 g = 1.25 g/L
22.4 L
Assume that you
have 1 mole of N2

6. 2. Calculate the density of CO2 at STP.
Density = grams
litre
Assume that you
have 1 mole of CO2

7. 2. Calculate the density of CO2 at STP. Calculate
Density = grams
litre
44.0 g =
Assume that you
have 1 mole of CO2

8. 2. Calculate the density of CO2 at STP. Calculate
Density = grams
litre
44.0 g =
22.4 L
Assume that you
have 1 mole of CO2

9. 2. Calculate the density of CO2 at STP. Calculate
Density = grams
litre
44.0 g = 1.96 g/L
22.4 L
Assume that you
have 1 mole of CO2

10. 3. Calculate the volume of O2 gas produced at STP for the
3. Calculate the volume of O2 gas produced at STP for the complete decomposition of 12.5 g HgO if the yield is 45.0 %.
2HgO → 2Hg + O2
12.5 g ? L 1 2

11. 3. Calculate the volume of O2 gas produced at STP for the
3. Calculate the volume of O2 gas produced at STP for the complete decomposition of 12.5 g HgO if the yield is 45.0 %.
2HgO → 2Hg + O2
12.5 g ? L
12.5 g HgO x 1mole
216.6g

12. 3. Calculate the volume of O2 gas produced at STP for the
3. Calculate the volume of O2 gas produced at STP for the complete decomposition of 12.5 g HgO if the yield is 45.0 %.
2HgO → 2Hg + O2
12.5 g ? L
12.5 g HgO x 1mole x 1 mole O2
216.6g mole HgO

13. 3. Calculate the volume of O2 gas produced at STP for the
3. Calculate the volume of O2 gas produced at STP for the complete decomposition of 12.5 g HgO if the yield is 45.0 %.
2HgO → 2Hg + O2
12.5 g ? L
12.5 g HgO x 1mole x 1 mole O2 x L
216.6g mole HgO mole

14. 3. Calculate the volume of O2 gas produced at STP for the
3. Calculate the volume of O2 gas produced at STP for the complete decomposition of 12.5 g HgO if the yield is 45.0 %.
2HgO → 2Hg + O2
12.5 g ? L
12.5 g HgO x 1mole x 1 mole O2 x L x
216.6g mole HgO mole

15. 3. Calculate the volume of O2 gas produced at STP for the
3. Calculate the volume of O2 gas produced at STP for the complete decomposition of 12.5 g HgO if the yield is 45.0 %.
2HgO → 2Hg + O2
12.5 g ? L
12.5 g HgO x 1mole x 1 mole O2 x L x = L
216.6g mole HgO mole

16. 4. How many litres of CO2 are produced by the reaction of 100. g
4. How many litres of CO2 are produced by the reaction of 100. g of Fe2O3, if the actual yield was 19.0 STP, calculate the percentage yield.
19.0 L
2Fe2O3 + 3C  4Fe + 3CO2
100. g ? L 3 2

17. 4. How many litres of CO2 are produced by the reaction of 100. g
4. How many litres of CO2 are produced by the reaction of 100. g of Fe2O3, if the actual yield was 19.0 STP, calculate the percentage yield.
19.0 L
2Fe2O3 + 3C  4Fe + 3CO2
100. g ? L
100. g Fe2O3 x 1 mole x 3 mole CO2 x L = L
159.6 g mole Fe2O mole
Percentage yield = L x 100% = %
21.05 L 3 2