Question

When the following equation is balanced with the smallest possible integer coefficients, what is the coefficient of H+?

Answer 1

Answer

D. 6

Explanation

Given that:

$Cr+H^+\rightarrow Cr^{3+}+H_2$

What to find:

The coefficient of H⁺ when the given equation is balanced with the smallest possible integer coefficients.

Solution:

The given equation is an example of an oxidation-reduction (redox) reaction

The first step is to identify the half equations:

$\begin{gathered} Oxidation:Cr\rightarrow Cr^{3+} \\ \\ Reduction:H^+\rightarrow H_2 \end{gathered}$

The next step is to balance the half equations molecularly follow by balancing the charge:

$\begin{gathered} Oxidation:Cr\rightarrow Cr^{3+}+3e^-\times2 \\ \\ Reduction:2H^++2e^-\rightarrow H_2\times3 \\ \\ Multiply\text{ }oxidation\text{ }half\text{ }equation\text{ }by\text{ }2\text{ }and\text{ }reduction\text{ }halfe\text{ }quation\text{ }by\text{ }3 \\ \\ Ox\imaginaryI dat\imaginaryI on:2Cr\rightarrow2Cr^{3+}+6e^- \\ \\ Reduction:6H^++6e^-\rightarrow3H_2 \end{gathered}$

The final step is to combine the half equations and simplified:

$2Cr+6H^+\rightarrow2Cr^{3+}+3H_2$

Therefore, the coefficient of H⁺ in the balanced equation above is 6.

The correct answer is D. 6