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

Qualification => Subject Doubts => GCE AS & A2 Level => Sciences => Topic started by: ruby92 on March 17, 2010, 02:47:36 pm

Title: chemistry:enthalpy changes !!!!!!
Post by: ruby92 on March 17, 2010, 02:47:36 pm

the chief gas in bio gas is methane
(a)the standard enthalphy change of formation deltaH_f (CH4) cannot be measured directly.
i calculate the standard enthalpy change of formation of methane from the deltaH_c values below
     substance        deltaH_c
CH4                          -890
C                             -393.5
H2                            -285.9

ii suggest why the enthalpy change of formation of methane cannot be measured directly?

Title: Re: chemistry:enthalpy changes !!!!!!
Post by: Saladin on March 18, 2010, 04:47:37 am

There u go.

Title: Re: chemistry:enthalpy changes !!!!!!
Post by: ruby92 on March 18, 2010, 03:32:07 pm

thnk u so muchhh :D