Question

the electrons are on the reactants side of the half-reaction.
?e⁻ + 2h⁺ + no₃⁻ → no₂ + h₂o
how many electrons are required to balance the charge in the half-reaction?

Explanation:

Step1: Calculate charge on reactants side

The reactants are $e^-$, $2H^+$, and $NO_3^-$. Let the number of electrons be $x$. The charge from electrons is $-x$ (since each $e^-$ has charge -1), from $H^+$ is $2\times(+1) = +2$, and from $NO_3^-$ is -1. So total reactant charge: $-x + 2 - 1=-x + 1$.

Step2: Calculate charge on products side

The products are $NO_2$ and $H_2O$. Both are neutral, so total product charge is 0.

Step3: Set charges equal and solve for x

For charge balance, reactant charge = product charge:
$$-x + 1 = 0$$
Solving for $x$:
$$-x = -1$$
$$x = 1$$

Answer:

1