Answer:
64.0 g/mol.
Explanation:
- Thomas Graham found that, at a constant temperature and pressure the rates of effusion of various gases are inversely proportional to the square root of their masses.
<em>∨ ∝ 1/√M.</em>
where, ∨ is the rate of diffusion of the gas.
M is the molar mass of the gas.
<em>∨₁/∨₂ = √(M₂/M₁)</em>
∨₁ is the rate of effusion of the unknown gas.
∨₂ is the rate of effusion of He gas.
M₁ is the molar mass of the unknown gas.
M₂ is the molar mass of He gas (M₂ = 4.0 g/mol).
<em>∨₁/∨₂ = 0.25.</em>
∵ ∨₁/∨₂ = √(M₂/M₁)
∴ (0.25) =√(4.0 g/mol)/(M₁)
<u><em>By squaring the both sides:</em></u>
∴ (0.25)² = (4.0 g/mol)/(M₁)
∴ M₁ = (4.0 g/mol)/(0.25)² = 64.0 g/mol.
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Answer:
Number of moles = 0.003 mol
Explanation:
Given data:
Molarity of HCl = 0.300 M
Volume = 10.0 mL (0.01 L)
Number of moles of HCl added = ?
Solution:
Formula:
Molarity = number of moles / volume in litter
Number of moles = Molarity × volume in litter
Number of moles = 0.300 mol/L × 0.01 L
Number of moles = 0.003 mol
Molar mass NH3 = 17.031 g/mol
1 mole NH3 -------------- 17.031 g
?? moles NH3 ---------- 346 g
346 x 1 / 17.031
=> 20.31 moles of NH3