Question

Study the following unbalanced half-reaction. Which equation represents the balanced half-reaction? H2O2 ---> H2O

Answer 1

Answer : The correct option is, $2e^-+2H^++H_2O_2\rightarrow 2H_2O$

Explanation :

The given unbalanced reaction is,

$H_2O_2\rightarrow H_2O$

(1) The right side is lacking oxygen, so we add a water molecule to it :

$H_2O_2\rightarrow H_2O+H_2O$

or we can write as,

$H_2O_2\rightarrow 2H_2O$

(2) Now we have introduced more hydrogen, so we need to balance hydrogen on the left side in acidic solution, we get

$2H^++H_2O_2\rightarrow 2H_2O$

(3) Now all the atoms are balanced but charge is not balanced. We see that the left side there are two positive charge. So, we balance the charge by adding two negative charge on the left side in the reaction, we get

$2e^-+2H^++H_2O_2\rightarrow 2H_2O$

Therefore, the correct option is, $2e^-+2H^++H_2O_2\rightarrow 2H_2O$

Answer 2

O: 1*2 = 2*1 
H 2 + 2 = 2*2 

answer C hope you get it right