Question

I am struggling to understand how to find what is the reagent used in a reaction. I have these 4 problems and I must figure out what "reagent used in reaction". My classmate described the reagent as the ractant that is entirly consumed when a reaction goes to completion. It determines how much of a product you can make.

Cu(s) + 4 HNO3 (aq) –> Cu(NO3)2 (aq) + 2NO2 (g) + 2H20

Cu(NO3)2 (aq) + 2NaOH (aq) –>Cu(OH)2 (s) + 2NaNO3 (aq)

CuSO4 (aq) + Zn (s) –>ZnSO4 (aq) + Cu (s)

H2SO4 (aq) + Zn (s) –>ZnSO4 (aq) + H2 (g)

Answer 1

1) Cu(s) + 4 HNO3 (aq) –> Cu(NO3)2 (aq) + 2NO2 (g) + 2H20

Reagent: HNO3 (aq). As HNO3 (aq) is oxidizing agent for oxidation of Cu(0) to Cu(+2).

2) Cu(NO3)2 (aq) + 2NaOH (aq) –>Cu(OH)2 (s) + 2NaNO3 (aq)

Reagent: NaOH. As NaOH provides neccessary Hydroxyl ions (HO-) which displaces NO3- ions and forms a ppt with Cu2+ ions i.e. Cu(OH)2 (s).

3) CuSO4 (aq) + Zn (s) –>ZnSO4 (aq) + Cu (s)

Reagent : CuSO4. As CuSO4 that provides Cu2+ which get reduced to Cu(0) and oxidizes Zn(0) to Zn(+2).

4) H2SO4 (aq) + Zn (s) –>ZnSO4 (aq) + H2 (g)

Reagent : H2SO4. As H2SO4 oxidizes Zn(0) to Zn(+2).

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