Why Is HNO3 Split Up in the Reactants Side?

[r_swayze]

CuS precipitates dissolve in hot HNO3. The hot HNO3 oxidizes the sulfide ion in the precipitates to free elemental sulfur, forming NO(g) as its reduction product. For CuS,

3CuS(s) + 8H(aq) + 2NO3(aq) = 3Cu(aq) + 2NO(g) + 3S(s) + 4H2O(l)

I have a few questions here.
Why is HNO3 split up on the reactants side?
Does it matter what the coefficient is of CuS?
if so, how do know whether it 3 or 4 or 2?

 

[Borek]

First: there should be charges in the equation.

Second: nitric acid is dissociated in water solutions.

Third: do you know what it means "balanced reaction equation"?

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methods