Answer:
C.0.28 V
Explanation:
Using the standard cell potential we can find the standard cell potential for a voltaic cell as follows:
The most positive potential is the potential that will be more easily reduced. The other reaction will be the oxidized one. That means for the reactions:
Cu²⁺ + 2e⁻ → Cu E° = 0.52V
Ag⁺ + 1e⁻ → Ag E° = 0.80V
As the Cu will be oxidized:
Cu → Cu²⁺ + 2e⁻
The cell potential is:
E°Cell = E°cathode(reduced) - E°cathode(oxidized)
E°cell = 0.80V - (0.52V)
E°cell = 1.32V
Right answer is:
<h3>C.0.28 V
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Answer:
Option D. 30 g
Explanation:
The balanced equation for the reaction is given below:
2Na + S —> Na₂S
Next, we shall determine the masses of Na and S that reacted from the balanced equation. This is can be obtained as:
Molar mass of Na = 23 g/mol
Mass of Na from the balanced equation = 2 × 23 = 46 g
Molar mass of S = 32 g/mol
Mass of S from the balanced equation = 1 × 32 = 32 g
SUMMARY:
From the balanced equation above,
46 g of Na reacted with 32 g of S.
Finally, we shall determine the mass sulphur, S needed to react with 43 g of sodium, Na. This can be obtained as follow:
From the balanced equation above,
46 g of Na reacted with 32 g of S.
Therefore, 43 g of Na will react with = (43 × 32)/46 = 30 g of S.
Thus, 30 g of S is needed for the reaction.
Answer:
1.85 g
Explanation:
The strategy here is to utilize the Henderson-Hasselbach equation
pH = pKa + log [A⁻] / [HA]
to calculate the ratio log [A⁻] / [HA], and from there to calculate the concentration [A⁻] and finally the mass of NaNO₂ from the number of moles assuming the final buffer volume is 50.0 mL ( that is the volume does not change by the addition of NaNO₂)
pH = pKa + log [NO₂⁻]/[HNO₂]
3.13 = 3.40 + log [NO₂⁻]/[HNO₂]
- 0.27 = log [NO₂⁻]/[HNO₂]
taking the inverse log function to both sides of this equation
0.54 = [NO₂⁻]/[HNO₂]
Now [HNO₂] = 1.0 M, therefore [NO₂⁻] = [NaNO₂] =
0.54 x 1.0 M = 0.54 M
from M = mol / L we get
mol = 0.54 mol/L x 0.050L = 0.027 mol
the molar mass of NaNO₂ is = 68.99 g / mol, so the mass of 0.027 mol is
0.027 mol x 68.99 g/mol = 1.85 g
Answer:
Choice B
They are polar climates because they are dry
and cold