The button batteries in small devices like watches are commonly composed of silver-zinc or mercury-zinc batteries. The reaction
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Answer:- molecules.
Solution:- The grams of tetrabromomethane are given and it asks to calculate the number of molecules.
It is a two step unit conversion problem. In the first step, grams are converted to moles on dividing the grams by molar mass.
In second step, the moles are converted to molecules on multiplying by Avogadro number.
Molar mass of = 12+4(79.9) = 331.6 g per mol
let's make the set up using dimensional analysis:
= molecules
So, there will be molecules in 250 grams of
.
Answer:
ΔG° = -118x10³ J/mol
Explanation:
The two half-reactions in the cell are:
Oxidation half-reaction:
Co(s) → Co²⁺(aq) + 2e⁻; E° = -0,28V
Reduction half-reaction:
Cu²⁺(aq)+2e⁻ → Cu(s); E° = 0,34V
The E° of the cell is defined as:
Replacing:
0,34V - (-0,28V) = 0,62V
It is possible to obtain the keq from E°cell with Nernst equation thus:
nE°cell/0,0592 = log (keq)
Where:
E°cell is standard electrode potential (0.62 V)
n is number of electrons transferred (2 electrons, from the half-reactions)
Replacing:
0,62V×2/0,0592 = log (keq)
20,946 = log keq
keq = 8,83x10²⁰≈ 5,88x10²⁰
ΔG° is defined as:
ΔG° = -RT ln Keq
Where R is gas constant (8,314472 J/molK) and T is temperature (298K):
ΔG° = -8,314472 J/molK×298K ln5,88x10²⁰
<em>ΔG° = -118x10³ J/mol</em>
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I hope it helps!