recently, my chem. teacher asked us to do experiment to find out the enthalpy change of a displacement reaction between zinc and copper sulpahte..

the details is taken from here,,

http://www.creative-chemistry.org.uk/al ... ch2-11.pdf

and my questions are that,,

with the reference of my experimental result,,

there are super large unacceptable errors,,

i recorded the total temperature change is only 35 ℃

assume the specific capacity of solution is equal to that of water
by E = mc △t
E = 25/1000* 1*159.6* 1/1000*4200*35

the enthaply change per one mole of zn is E/ 25/1000*1 = 23461Jmol-1

and this is impossible!! since the standard is 217*10^3 Jmol-1

besides,,, i used the standard result in the webpage to do a calculation

and Energy released =217*10^3 * 25/1000*1 = 5425J

by E = mc△t
5425 = mc△t

it is obvious that mass used is less than 10g - -|| (very small)
and c should be almost equal to that of water,,

thus,, there will be super large in magnitue in temperature difference,,

△t = 323 will it be possible???... the energy is large enough to boil the solution - -|||

maybe there is a great energy loss to the surroundings,,

but if used the standard one, it is still impossible..

Plx telll me the wt's wrong.. thx~