Please, can anyone give me the actual value of the amount of heat given off (in KJ/mol) when Sodium Hydride reacts with water? And the stoichiometry of the reaction?
The actual amount of heat increases with the amount of water available to dissolve the NaOH, but the dilution would temper any temperature rise. The &[ignore]Delta[/ignore];H[sub]Rxn[/sub] below uses the value for NaOH(aq, 400 H[sub]2[/sub]O):
The heat of reaction is 10% less if your product is concentrated sodium hydroxide solution. NBS Circular 500 gives the heat of formation of sodium hydroxide as a function of dilution. For example,
NaH(c) + 4 H2O(l) --> NaOH:3H2O + H2(g)