half ionic equations. How many electrons are needed to balance each one?

Question

a) Ca2+ to Ca
b) 2I- to I2
c) 4OH- to 2H2O + O2
d) H2S to S + 2H+

Answer 1

a) Ca2+ + 2e- >> Ca

b) 2 I- >> I2 + 2e-

c) 4 OH- >> O2 + 2H2O + 4e-

d) H2S >> S + 2H+ + 2e-

Answer 2

Ca(2+) + 2 e ==> Ca

2 I(-) ==> I2 + 2 e

4 OH(-) ==> 2 H2O + O2 + 4 e

H2S ==> S + 2 H(+) + 2 e

Answer 3

2, 2, 4 and 2.

Look at the change in oxidation state of the element that changes.