Activity 3.9:
Solving problems involving the number of particles, number of moles, mass of substances and volume of gases at STP or room conditions
1. Carry out this activity in groups.
2. Read and answer the following questions.
[Relative atomic mass: H = 1, He = 4, C = 12, N = 14, O = 16, Al = 27, S = 32; Avogadro constant, NA : 6.02 × 1023 mol–1; Molar volume = 22.4 dm3 mol–1 at STP or 24 dm3 mol–1 at room conditions]
(a) Calculate the number of atoms found in the following substances:
(i) 6.75 g of aluminium, Al
(ii) 5.1 g of ammonia gas, NH3
(b) Calculate the volume of the following gases at STP.
(i) 5.6 g of nitrogen gas, N2
(ii) 1.204 × 1022 helium atoms, He
(c) What is the mass of oxygen gas, O2 that has the same number of molecules as in 8 g of sulphur trioxide gas, SO3?
(d) A sample of methane gas, CH4 occupies a volume of 9.84 dm3 at room conditions. How many molecules are found in that sample? Calculate the mass of the sample.
(e) A reaction releases 120 cm3 of carbon dioxide gas, CO2 per minute at room conditions. Calculate the total mass of carbon dioxide, CO2 released after 10 minutes.
3. Write the calculation steps for questions (a) to (e) clearly and systematically on a piece of flip chart paper.
4. Present your group solution in front of the class.
Answer:
2. (a) (i) 1.505 × 1023 atoms
(ii) 7.224 × 1023 atoms
(b) (i) 4.48 dm
(ii) 0.448 dm3
(c) 3.2 g
(d) 2.4682 × 1023 methane molecules; 6.56 g
(e) 2.2 g
Solving problems involving the number of particles, number of moles, mass of substances and volume of gases at STP or room conditions
1. Carry out this activity in groups.
2. Read and answer the following questions.
[Relative atomic mass: H = 1, He = 4, C = 12, N = 14, O = 16, Al = 27, S = 32; Avogadro constant, NA : 6.02 × 1023 mol–1; Molar volume = 22.4 dm3 mol–1 at STP or 24 dm3 mol–1 at room conditions]
(a) Calculate the number of atoms found in the following substances:
(i) 6.75 g of aluminium, Al
(ii) 5.1 g of ammonia gas, NH3
(b) Calculate the volume of the following gases at STP.
(i) 5.6 g of nitrogen gas, N2
(ii) 1.204 × 1022 helium atoms, He
(c) What is the mass of oxygen gas, O2 that has the same number of molecules as in 8 g of sulphur trioxide gas, SO3?
(d) A sample of methane gas, CH4 occupies a volume of 9.84 dm3 at room conditions. How many molecules are found in that sample? Calculate the mass of the sample.
(e) A reaction releases 120 cm3 of carbon dioxide gas, CO2 per minute at room conditions. Calculate the total mass of carbon dioxide, CO2 released after 10 minutes.
3. Write the calculation steps for questions (a) to (e) clearly and systematically on a piece of flip chart paper.
4. Present your group solution in front of the class.
Answer:
2. (a) (i) 1.505 × 1023 atoms
(ii) 7.224 × 1023 atoms
(b) (i) 4.48 dm
(ii) 0.448 dm3
(c) 3.2 g
(d) 2.4682 × 1023 methane molecules; 6.56 g
(e) 2.2 g