Question:   What is the equation for when metals react with acids?

Answer:

Generally, metals react with acids to form hydrogen and an ionic compound where the metal is the cation and the anion from the acid is the anion.  The general form for these equations is:

Where "M" is the metal, "HA" is the acid, and "MA" is the ionic compound formed when the metal reacts with the acid.  Typically, the ionic compound is dissolved in water after this reaction takes place, while hydrogen, as you're probably aware, is a gas.

You may have noticed that the reaction above isn't balanced.  The reason for that is that depending on the oxidation state of the metal and the formula of the acid, there may be various coefficients in front of these formulas.  The idea, however, is completely accurate, so just treat the above as an equation that will need balancing and you'll be in good shape.

Here are some examples:

When iron reacts with hydrochloric acid:  Fe + 2 HCl --> FeCl₂ + H₂
When sodium reacts with sulfuric acid:  2 Na + H₂SO₄ --> Na₂SO₄ + H₂

Anyhow, I suppose you probably get the idea.  Basically, it's just a single displacement reaction of the metal with the acid to form hydrogen!