IGCSE/GCSE/O & A Level/IB/University Student Forum

Qualification => Subject Doubts => GCE AS & A2 Level => Sciences => Topic started by: joel on April 21, 2010, 12:06:23 pm

Title: Chemistry Dout
Post by: joel on April 21, 2010, 12:06:23 pm

Explain why the standard enthalpy change of formation for water is identical to the standard enthalpy change of combustion of hydrogen.

Taken from 9701/02/O/N/03 Question 3 (a) (iii)

Title: Re: Chemistry Dout
Post by: The SMA on April 21, 2010, 02:38:24 pm

Standard enthalphy change of formation of water and Standard enthalphy change of combustion of Hydrogen are the same because Hydrogen reacts with oxygen to form water.

Standard enthalphy change of formation of water:
H2 (g)  + 1/2 O2 (g) --> H2O (l)   -286kj/mol

Standard enthalphy change of combustion of Hydrogen:
H2 (g) + 1/2 O2 (g) --> H2O (l)    -286kj/mol