Answer:
A) 
B) 7.5 molar
Explanation:
A) <u>Reduction</u>

<u>Oxidation</u>

Multiplying the oxidation reaction by 5/2 and adding it to the reduction equation:

+

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B) 10 ml = 0.01 L
20 ml = 0.02 L
mol of MnO4− = molarity*volume = 1.5*0.02 = 0.03
1 mol of MnO4− reacts with 5/2 mol of H2O2, then:
mol of H2O2 = 0.03*5/2 = 0.075
molarity = mol/volume = 0.075/0.01 = 7.5 molar
Answer:
It takes 86 days take to cover half of the lake
Explanation:
In the day #1, the amount of the algae is X,
In the day #2 is 2X
In the day #3 is 2*2*X = X*2²
...
In the day #n the amount of the algae is X*2^(n-1)
Assuming X = 1m³. In the day 87, the area infected was:
1m³*2^(87-1)
7.74x10²⁵m³ is the total area of the lake
the half of this amount is 3.87x10²⁵m³
The time transcurred is:
3.87x10²⁵m³ = 1m³*2^(n-1)
Multiplying for 5 in each side:
ln (3.87x10²⁵) = ln (2^(n-1))
58.9175 = n-1 * 0.6931
85 = n-1
86 = n
<h3>It takes 86 days take to cover half of the lake</h3>