Question

The following reaction occurs spontaneously. 2H+(aq)+ca(s) Ca2+(aq)+H2(g)

write the balanced reduction half-reaction

Answer 1

Don't you realize that we can only guess when you don't include an arrow? We can only guess as to the reactants versus the products. I'm guessing you made two mistakes. First ca(s) PROBABLY is Ca(s) and the arrow PROBABLY goes like this.
2H^+(aq) + Ca(s) ==> Ca^+2(aq) + H2(g).
Do you know the definitions of oxidation and reduction?
Reduction is the gain of electrons. Oxidation is the loss of electrons. First we pick out what is what.
H goes from an oxidation state of +1 on the left to 0 on the right. That's a gain of electrons.
Ca goes from an oxidation state of 0 on the left to +2 on the right. That's a loss of electrons.
So Ca is oxidized and H^+ is reduced.
Reduction half.
2H^+(aq) + 2e ==> H2(g)
Oxidation half.
Ca(s) ==> Ca^+2(aq) + 2e

Answer 2

Hey man just wondering is the reductant in the equation considered 2H^+ or simply H^+

Answer 3

simply H+