Calcium has the greatest mass of the first twenty elements with a mass of approximately 40.08
Answer:
6Fe^2+(aq) -------> 6Fe^3+(aq) + 6e
Explanation:
The balanced oxidation half equation is;
6Fe^2+(aq) -------> 6Fe^3+(aq) + 6e
A redox reaction is actually an acronym for oxidation-reducation reaction. Since the both reactions are complementary, there can't be oxidation without reduction and there can't be reduction without oxidation.
The main characteristic of redox reactions is that electrons are transferred in the process. The number of electrons transferred is usually deduced from the balanced reaction equation. For this reaction, the balanced overall reaction equation is;
Cr2O7^2–(aq) + 6Fe^2+(aq) +14H^+(aq)→ 2Cr^3+(aq) + 6Fe^3+ (aq) + 7H2O(l)
It is clear from the equation above that six electrons were transferred. Thus six Fe^2+ ions lost one electron each in the oxidation half equation as shown in the balanced oxidation half equation above.
From the statement of Hess' law, the enthalpy of the reaction A---> C is +90 kJ
<h3>What is Hess' law?</h3>
Hess' law of constant heat summation states that for a multistep reaction, the standard enthalpy of reaction is always constant and is independent of the pathway or intermediate routes taken.
From Hess' law, the enthalpy change for the reaction A ----> C is calculated as follows:
A---> C = A ---> B + B ---> C
ΔH of A---> C = 30 kJ + 60 kJ
ΔH = 90 kJ
Therefore, the enthalpy of the reaction A---> C is +90 kJ
The above reaction A---> C can be shown in the enthalpy diagram below:
A -------------------> C (ΔH = +90 kJ)
\ /
\ / (ΔH = +60 kJ)
(ΔH = +30 J) \ /
> B
Learn more about enthalpy and Hess law at: brainly.com/question/9328637
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