What gas is released when acid added to a metal?

1 Answer
Truong-Son N.
May 10, 2017

Depends on what acid and what metal...

Two acids that are often reacted with metals are "HNO"_3 and "HCl". The former follows the bb("NO"_3^(-)) reduction

"NO"_3^(-)(aq) + 4"H"^(+)(aq) + 3e^(-) -> "NO"(g) + 2"H"_2"O"(l)

and the latter from the Standard Hydrogen Electrode

2"H"^(+)(aq) + 2e^(-) -> "H"_2(g).

If and only if a reaction occurs, then either "H"_2(g) is released from reaction with "HCl"(aq), or "NO"(g) is released from reaction with "HNO"_3(aq).

But you must decide which acid you refer to...

CHALLENGE: Which of the following is dissolved by "HNO"_3 but not "HCl"?

  • "Au"
  • "Ag"
  • "Fe"
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