Answers:
D) 27 g
Step-by-step explanation:
(1) Calculate the mass of Ca
(a) Calculate the volume of the block
V = lwh
V = 4.2 cm × 3.5 cm × 3.0 cm
V = 44.1 cm³
(b) Calculate the mass of the block·
ρ = m/V Multiply each side by V
m = Vρ
m = 44.1 cm³ × (1.55 g/1 cm³)
m = 68.4 g
(2) Calculate the mass of oxygen
We know we will need a balanced equation with masses and molar masses, so let’s gather all the information in one place.
M_r: 40.08 32.00
2Ca + O₂ ⟶ CaO
m/g: 68.4
(a) Calculate the moles of Ca
n = 68.4 g Ca ×1 mol Ca/40.08 g NH₃
n = 1.71 mol Ca
(b) Calculate the moles of O₂
The molar ratio is (1 mol O₂/2 mol Ca)
n = 1.71 mol Ca × (1 mol O₂/2 mol Ca)
n = 0.853 mol O₂
(c) Calculate the mass of O₂
Mass of O₂ = 0.853 mol O₂ × (32.00 g O₂/1 mol O₂)
Mass of O₂ = 27 g O₂