Answer:
2.01
Explanation:
The effusion is the passage of the molecules by a small hole by a difference of pressure. By Graham's Law, the rate of the effusion is inversely proportional to the square of the molar mass of the compound. Thus,
rateHF/rateHBr = √MHBr /√MHF
MHBr = 81 g/mol
MHF = 20 g/mol
rateHF/rateHBr = √81/√20
rateHF/rateHBr = 2.01
Answer:
(a) Cu²⁺ +2e⁻ ⇌ Cu
(c) 0.07 V
Explanation:
(a) Cu half-reaction
Cu²⁺ + 2e⁻ ⇌ Cu
(c) Cell voltage
The standard reduction potentials for the half-reactions are+
<u> E°/V
</u>
Cu²⁺ + 2e⁻ ⇌ Cu; 0.34
Hg₂Cl₂ + 2e⁻ ⇌ 2Hg + 2Cl⁻; 0.241
The equation for the cell reaction is
E°/V
Cu²⁺(0.1 mol·L⁻¹) + 2e⁻ ⇌ Cu; 0.34
<u>2Hg + 2Cl⁻ ⇌ Hg₂Cl₂ + 2e⁻; </u> <u>-0.241
</u>
Cu²⁺(0.1 mol·L⁻¹) + 2Hg + 2Cl⁻ ⇌ Cu + Hg₂Cl₂; 0.10
The concentration is not 1 mol·L⁻¹, so we must use the Nernst equation
(ii) Calculations:
T = 25 + 273.15 = 298.15 K
![Q = \dfrac{\text{[Cl}^{-}]^{2}}{ \text{[Cu}^{2+}]} = \dfrac{1}{0.1} = 10\\\\E = 0.10 - \left (\dfrac{8.314 \times 298.15 }{2 \times 96485}\right ) \ln(10)\\\\=0.010 -0.01285 \times 2.3 = 0.10 - 0.03 = \textbf{0.07 V}\\\text{The cell potential is }\large\boxed{\textbf{0.07 V}}](https://tex.z-dn.net/?f=Q%20%3D%20%5Cdfrac%7B%5Ctext%7B%5BCl%7D%5E%7B-%7D%5D%5E%7B2%7D%7D%7B%20%5Ctext%7B%5BCu%7D%5E%7B2%2B%7D%5D%7D%20%3D%20%5Cdfrac%7B1%7D%7B0.1%7D%20%3D%2010%5C%5C%5C%5CE%20%3D%200.10%20-%20%5Cleft%20%28%5Cdfrac%7B8.314%20%5Ctimes%20298.15%20%7D%7B2%20%5Ctimes%2096485%7D%5Cright%20%29%20%5Cln%2810%29%5C%5C%5C%5C%3D0.010%20-0.01285%20%5Ctimes%202.3%20%3D%200.10%20-%200.03%20%3D%20%5Ctextbf%7B0.07%20V%7D%5C%5C%5Ctext%7BThe%20cell%20potential%20is%20%7D%5Clarge%5Cboxed%7B%5Ctextbf%7B0.07%20V%7D%7D)
Answer:
22.9 moles (Option 5)
Explanation:
A substance is 35.7% carbon by mass, means that in 100 g of substance, 35.7 g are C.
The rule of three will be:
100 g of substance ___ have __ 35.7 g of C
769 g of substance ___ have ___ ( 769 . 35.7) / 100 = 274.5 g of C
1 mol of C = 12 g/m
Mass / Molar mass = Moles
274.5 g / 12g/m = 22.9 moles
Answer: 3.28 mins
Explanation:
Heres the explanation:
Conversions
74mph = 33.08 m/s
6.5 km = 6500 m
(6500m)/(33.08m/s) = 196.5 seconds
196.5 secs = 3.28 mins