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How does the Heat neutralization of Hcl and base and CH3COOH and base differ? I got very similar results for both- 656 Cal/mole and -650 Cal/mole. What does this mean? I thought they would be different!??
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the heat of neutralisation should be less for a weak acid and strong base as energy is needed to dissociate the weak acid in the equilibrium.
The value for strong acid strong base = 57kJmol-1 water formed (your values are very low suggesting either experimental or calculations errors - in calories it is 57000 / 4.186 = 13619 Calories)
In reality there is very little observable difference between weak acids and strong bases as the usual experimental errors mask the difference in enthalpy. It is not surprising that you found no difference when your margin of error was approx 95% !!!
Experimental errors arise from
1. heat lost to the environment by radiation, conduction and convection
2. heat used to change the temp of the thermometer and container
3. difference between shc of water and solutions used
4. volume and mass measurement inaccuracy
5. thermometer inaccuracy
but I fear that with such a large error you have made a more fundamental mistake in the calculations (correcting for 1 mole of water formed perhaps?)