Answer:
1. 2.41 × 1023 formula units
2. 122 L
3. 7.81 L
Explanation:
1. Equation of the reaction: 2 Na(NO3) + Ca(CO3) ---> Na2(CO3) + Ca(NO3)2
Mole ratio of NaNO3 to CaCO3 = 2 : 1
Moles of CaCO3 = mass/molar mass
Mass of CaCO3 = 20 g; molar mass of CaCO3 = 100 g
Moles of CaCO3 = 20 g/100 g/mol = 0.2 moles
Moles of NaNO3 = 2 × 0.2 moles = 0.4 moles
1 Mole of NaNO3 = 6.02 × 10²³ formula units
0.4 moles of NaNO3 = 0.4 × 6.02 × 10²³ = 2.41 × 1023 formula units
2. Equation of reaction : 2 H2O ----> 2 H2 + O2
Mole ratio of oxygen to water = 1 : 2
At STP contains 6.02 × 10²³ molecules = 1 mole of water
6.58 × 10²⁴ molecules = 6.58 × 10²⁴ molecules × 1 mole of water/ 6.02 × 10²³ molecules = 10.93 moles of water
Moles of oxygen gas produced = 10.93÷2 = 5.465 moles of oxygen gas
At STP, 1 mole of oxygen gas = 22.4 L
5.465 moles of oxygen gas = 5.465 moles × 22.4 L/1 mole = 122 L
3.Equation of reaction: 6 K + N2 ----> 2 K3N
Mole ratio of Nitrogen gas and potassium = 6 : 1
Moles potassium = mass/ molar mass
Mass of potassium = 90.0 g, molar mass of potassium = 39.0 g/mol
Moles of potassium = 90.0 g / 39.0 g/mol = 2.3077moles
Moles of Nitrogen gas = 2.3077 moles / 6 = 0.3846 moles
At STP, 1 mole of nitrogen gas = 22.4 L
0.3486 moles of oxygen gas = 0.3486 moles × 22.4 L/1 mole = 7.81 L
