1. Molarity : 0.25 M
2. mol CH₄ = 7.4 moles
mol O₂ = 14.8 moles
<h3>Further explanation</h3>
1.
Given
83.2 g CuCl2 in 2.5 liters of water
Required
the molarity
Solution
Molarity : mol solute per liter of solution(not per liter of solvent)
mol solute = mol CuCl₂
mol CuCl₂ = mass : MW CuCl₂
mol CuCl₂ = 83.2 : 134.45
mol CuCl₂ = 0.619
Molarity(M) = mol : V
Assume density CuCl₂ = 3.39 g/cm³
volume CuCl₂ = 8.32 g : 3.39 g/cm³ = 2.45 cm³=2.45 x 10⁻³ L
With this small volume value of CuCl₂, the volume of the solute is sometimes neglected in calculating molarity
volume of solution = 2.5 L + 2.45 x 10⁻³ L = 2.50245 L
Molarity(M) = mol : V
M = 0.619 : 2.50245 L = 0.247≈0.25
2.
Given
Reaction
The correct balanced reaction:
CH4 + 2O2 → CO2 + 2H2O
7.4 moles CO2
Required
moles of methane (CH4) and oxygen gas (O2)
Solution
From the equation, mol ratio of CO₂ : CH₄ : O₂ = 1 : 1 : 2
mol CH₄ = mol CO₂ = 7.4 moles
mol O₂ = 2 x mol CO₂ = 2 x 7.4 moles = 14.8 moles
