Zn can reduce  NO₃^– to NH₃(g) in basic solution. (The following equation is not balanced.)

The NH₃ can be neutralized with an excess of HCl(aq). Then, the unreacted HCl can be titrated with NaOH. In this way a quantitative determination of NO₃^– can be achieved. A 25.00 mL sample of nitrate solution was treated with zinc in basic solution. The NH₃(g) was passed into 50.00 mL of 0.1500 M HCl. The excess HCl required 32.10 mL of 0.1000 M NaOH for its titration. What was the [NO₃^–] in the original sample?

Transcribed Image Text:

NO3 (aq) +Zn(s) + OH¯ (aq) + H₂O(1) [Zn(OH)4]² (aq) + NH3(g)