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Hydration Enthalpy of Sodium Hydride.

Hydration Enthalpy of Sodium Hydride.

Hydration Enthalpy of Sodium Hydride.

(OP)
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?

RE: Hydration Enthalpy of Sodium Hydride.

The reaction is

    NaH(c) + H2O(l) --> NaOH(aq) + H2(g)

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 ΔHRxn below uses the value for NaOH(aq, 400 H2O):

ΔHRxn, 25 C = -112 + 0 –(-14) –(-68) = -30 kcal/mol

Data are from Perry’s, 7th ed.

RE: Hydration Enthalpy of Sodium Hydride.

(OP)
Thank you very much, kenvlach. Very helpful.

RE: Hydration Enthalpy of Sodium Hydride.

(OP)
Thank you very much, kenvlach. Very helpful.

RE: Hydration Enthalpy of Sodium Hydride.

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)

delHRxn, 25 C = -108.9 + 0 –(-13.7) –(-68.3) = -26.9 kcal/mol

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