Reaction betwen magnesium&acid

Case I dil. HCl
Mg + 2HCl --> MgCl2 + H2
Mg dissoved to give a colourless solution
Colourless gas bubbles is observed

Case II conc. HCl (similar to reaction of dil. HCl and Mg, but faster rate)
Mg + 2HCl --> MgCl2 + H2
Mg dissoved to give a colourless solution
Colourless gas bubbles is observed
Some white fume is observed (it is HCl(g) because the reaction is too vigorous)

Case III conc H2SO4 (an oxidizing agent)
Mg + 2H2SO4 --> MgSO4 + SO2 + 2H2O
Mg dissoved to give a colourless solution
Colourless gas bubbles is observed
Pungent smell (SO2(g))

Case IV very dilute HNO3 (serves as normal acid , NOT OA)
Mg + 2HNO3 --> Mg(NO3)2 + H2
Mg dissoved to give a colourless solution
colourless gas bubbles is observed

2009-04-10 02:28:46 補充：
Sorry
it should be
Case III dilute H2SO4
Mg + H2SO4 --> MgSO4 + H2
Mg dissoved to give a colourless solution
Colourless gas bubbles is observed

Magnesium reacts with acid solutions to give hydrogen gas, except that when oxidizing acids (usually dilute/concentrated nitric acid, and concentrated sulphuric acid) are used.

The four acid solutions (dilute/concentrated hydrochloric acid, dilute sulphuric acid, and very dilute nitric acid) used are not oxidizing. Therefore, in all of the 4 cases, hydrogen gas is given off.

The full equation and ionic equation for the reaction between magnesium and dilute hydrochloric acid are:
Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g)
Mg(s) + 2H+(aq) → Mg2+(aq) + H2(g)

The full equation and ionic equation for the reaction between magnesium and concentrated hydrochloric acid are:
Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g)
Mg(s) + 2H+(aq) → Mg2+(aq) + H2(g)

The full equation and ionic equation for the reaction between magnesium and dilute sulphuric acid are:
Mg(s) + 2H2SO4(aq) → MgSO4(aq) + H2(g)
Mg(s) + 2H+(aq) → Mg2+(aq) + H2(g)

The full equation and ionic equation for the reaction between magnesium and very dilute nitric acid are:
Mg(s) + 2HNO3(aq) → Mg(NO3)2(aq) + H2(g)
Mg(s) + 2H+(aq) → Mg2+(aq) + H2(g)
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