The chemical reaction 2Cu + O2 → 2CuO + 315 kJ is an _____ reaction. Endothermic, combustion Exothermic, combustion Endothermic,
2 answers:
Answer: Exothermic
Explanation: Combustion reaction is a chemical reaction in which hydrocarbon burns in the presence of oxygen to form carbon dioxide, water and energy.
Exothermic reactions are those in which energy is released and endothermic reactions are those in which energy is absorbed.
A single replacement reaction is one in which a more reactive element displaces a less reactive element from its salt solution.
As in the given reaction, the energy is released thus reaction s exothermic.
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Answer:
Approximately .
Explanation:
Initial volume of the solution: .
Initial quantity of :
.
Ammonia reacts with hydrochloric
acid at a one-to-one ratio:
.
Hence, approximately of
molecules would be required to exactly react with the
in the original solution and hence reach the equivalence point of this titration.
Calculate the volume of that
solution required for reaching the equivalence point of this titration:
.
Hence, by the assumption stated in the question, the volume of the solution at the equivalence point would be approximately .
If no hydrolysis took place, of
would be produced. Because
is a soluble salt, the solution would contain
of
ions. The concentration of
would be approximately:
.
However, because is a weak base, its conjugate
would be a weak base.
.
Hence, the following reversible reaction would be take place in the solution at the equivalence point:
.
Let be the increase in the concentration of
in this solution because of this reversible reaction. (Notice that
.) Construct the following
table:
.
Thus, at equilibrium:
- Concentration of the weak acid:
.
- Concentration of the conjugate of the weak acid:
.
- Concentration of
:
.
.
Solve for . (Notice that the value of
is likely to be much smaller than
. Hence, the denominator on the left-hand side
.)
.
Hence, the concentration of at the equivalence point of this titration would be approximately
.
Hence, the at the equivalence point of this titration would be:
.