Thu July 28, 2011 By: Ruchika Saini

what happens when concentrated acid reacts with metal? what are the products and which gas comes out?

Expert Reply
Thu July 28, 2011
when conc. acid reacts with metal it liberates hydrogen gas and respective salt of the acid

Metal + Dilute acid ? Salt + Hydrogen

Bubbles of hydrogen gas can be seen on the surface.

Metals like sodium, potassium react violently.

2 Na + 2 HCl ? 2 NaCl + H2

Magnesium reacts quite rapidly with dilute HCl.
 Mg + 2 HCl ? MgCl2 + H2

Nitric acid (HNO3) is a strong oxidising agent. It oxidises the H2 gas produced to water and itself gets reduced to any of the nitrogen oxides (N2O, NO, NO2).that is Why  hydrogen gas is not evolved when a metal reacts with nitric acid

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