I need to balance the following net ionic equations which represent reactions to

Question

I need to balance the following net ionic equations which represent reactions to be performed in this lab experiment. I do not understand at all how to balance an equation. So any explanations would be appreciated.

___Cu(s) + ____H^+(aq) + ____ NO3^- (aq) ------> _____Cu^2+ (aq) + ____NO2(g) + ____H2O (l)

_____CuO(s) + _____H^+ (aq) + ______HSO4^ - (aq) ------> _____Cu^2+ (aq) + _____ SO4^2- (aq) + _____ H2O (l)

____Zn(s) + ____H^+(aq) -------> ______Zn^2+ + ___H2(g)

___Cu^2+ (aq) ____ Zn (s) ------> _____Cu (s) + _____ Zn ^2+

I am sorry to post more than one equation but the more that I see done the more I am able to learn. Thank you.

Explanation / Answer

Since all these reactions cntains H+ ions we need to balance all these reactions in acidic medium.

We can follow below steps to balance ionic equation in acidic medium.

To balance this reaction in acidic medium, first of all separate the oxidation and reduction-half reaction. Now balance all atoms except O and H atoms.

Now inorder to balance O - atom, we need to add 1 H2O molecule in opposite side for each excess oxygen atom and 2H+ on the same side.

Inorder to balance H - atom, we need to add 1 H+ ion in opposite side for each excess H-atom

Finally the number of electrons needs to be balanced on both sides.

1: Oxidation-half reaction: Cu(s) ------- > Cu2+(aq) + 2e-

Reduction-half reaction: 2x[NO3-(aq) + 2H+(aq) + 1e- -------- > NO2(g) + H2O] [we multiplied by 2 to cancel electron]

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Overall balanced reaction: Cu(s) + 2NO3-(aq) + 4H+(aq) ------ > Cu2+(aq) + 2NO2(g) + 2H2O (answer)

Q.3:

Oxidation-half reaction: Zn(s) ------- > Zn2+(aq) + 2e-

Reduction-half reaction: 2H+(aq) + 2e- -------- > H2(g)

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Overall balanced reaction: Zn(s) + 2H+(aq) ------ > Zn2+(aq) + H2(g) (answer)

Q.4:

Oxidation-half reaction: Zn(s) ------- > Zn2+(aq) + 2e-

Reduction-half reaction: Cu2+(aq) + 2e- -------- > Cu(s)

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Overall balanced reaction: Zn(s) + Cu2+(aq) ------ > Zn2+(aq) + Cu(s) (answer)

Q.2: CuO(s) + H+(aq) + HSO4-(aq) ------- >  Cu2+(aq) + SO42-(aq) + H2O(l) (answer)

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