Question

how do the following react with water
1.potassium hydride
2.Calcium hydride

Answer 1

Potassium hydride reacts violently with water to produce hydrogen gas and potassium hydroxide.

Calcium hydride reacts briskly with water to produce hydrogen gas and calcium hydroxide.

Both reactions proceed exothermically, but the degree of exothermicity (i.e. how hot it gets how quickly) is quite a bit more controlled for calcium hydride, when compared with potassium hydride.

CaH2 + 2H2O ===> Ca(OH)2 + 2H2(g)

KH + H2O ===> KOH + H2

Answer 2

1)KH reacts with water according to the reaction: KH + H2O → KOH + H.
2)Calcium hydride, CaH2, reacts with water to form hydrogen gas.
Calcium hydride, CaH2, reacts with water to form hydrogen gas. CaH2(s) + 2 H2O(l) Ca(OH)2(aq) + 2 H2(g)