Write balanced equation and name the products formed when:
(a) sodium hydrogencarbonate is added to nitric acid.
(b) cupric oxide reacts with nitric acid.
(c) zinc reacts with dilute nitric acid.
(d) concentrated nitric acid is heated.

(a) ${\mathrm{NaHCO}}_3+{\mathrm{HNO}}_3\to {\mathrm{NaNO}}_3+{\mathrm{H}}_2\mathrm{O}+{\mathrm{CO}}_2$
The products formed are sodium nitrate, water and carbon dioxide.
(b) $\mathrm{CuO}+2{\mathrm{HNO}}_3\to \mathrm{Cu}{\left({\mathrm{NO}}_3\right)}_2+{\mathrm{H}}_2\mathrm{O}$
The products are copper nitrate and water.
(c) The products are zinc nitrate, water and brown fumes of nitrogen dioxide.
(d) $4{\mathrm{HNO}}_3\stackrel{∆}{\to }2{\mathrm{H}}_2\mathrm{O}+4{\mathrm{NO}}_2+{\mathrm{O}}_2$
Heating concentrated nitric acid results in the formation of brown fumes of nitrogen dioxide.