<span>Chemical Energy is energy stored in the bonds of chemical compounds (atoms and molecules). It is released in a chemical reaction, often producing heat as a by-product (exothermic reaction). Batteries, biomass, petroleum, natural gas, and coal are examples of stored chemical energy.
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Answer:
9.1 seconds
Explanation:
Given that for a second order reaction
1/[A]t = kt + 1/[A]o
Where [A]t= concentration at time = t= 0.340M
[A]o= initial concentration = 0.820M
k= rate constant for the reaction=0.190m-1s-1
t= time taken for the reaction (the unknown)
Hence;
(0.340)^-1 = 0.190×t + (0.820)^-1
t= (0.340)^-1 - (0.820)^-1/0.190
t= 9.1 seconds
Hence the time taken for the concentration to decrease from 0.840M to 0.340M is 9.1 seconds.
Answer:

Explanation:
From the question we were given 0.155 moles of HBr, but Br and H are in ratio 1:1, then there are 0.155 moles of Br- ions.
We were also told that the solution contain NaBr, of 25.9 g. Then it must be converted to moles.
molar mass of NaBr =(22.99g + 79.90 )
= 102.89 g per mol.
the moles of NaBr can be calculated as 25.9 / 102.89
=0.252 moles
But Na and Br are in a ratio 1:1 , then there are 0.252 moles of Br-.
Then to get two Br- mol , we will add the first and second mol of Br- together
= 0.155 + 0.252
=0.407 moles.
The given solution has volume of 250 mL, but we know that there are 1000 ml in a liter, then if we convert to L for unit consistency we have
= 250/1000
= 0.25 L
molarity=0.407 moles/0.25 L
= 1.628 M.
Therefore, Br ion molarity is 1.628 M.