Alkali metals are so reactive that they react directly with water in the absence of acid. For Example...

Question

2 K(s) + 2 H2O(l) �¨ 2 K+(aq) + 2 OH− (aq) + H2(g).

How many milliliters of hydrogen will be evolved over water when 4.52 g K reacts with an excess of. H2O (l)?

Answer 1

Just follow the steps in this example.
http://www.jiskha.com/science/chemistry/stoichiometry.html