Energy and temperature change

[starburst.95]

can someone help me with this question pleeeeaase!!
   
In an experiment 100 ml of hydrochloric acid was poured into a calorimeter. Then, 0.427g of magnesium powder was added to the HCL. A temperature change of 7 degrees was recorded. calculate the energy change in joules that occured?
 
since no calibration factor was given nor any means of calculating the calibration factor can you use the formulae:
                                                                                               specific heat capacity of water x mass of HCL x temperature rise?

[Jenny_2108]

can someone help me with this question pleeeeaase!!
   
In an experiment 100 ml of hydrochloric acid was poured into a calorimeter. Then, 0.427g of magnesium powder was added to the HCL. A temperature change of 7 degrees was recorded. calculate the energy change in joules that occured?
 
since no calibration factor was given nor any means of calculating the calibration factor can you use the formulae:
                                                                                               specific heat capacity of water x mass of HCL x temperature rise?

I dont think we can use calibration factor

Its a diluted solution, we can assume its specific heat capacity is close to water's

Enery of solution=4.18 * 100 * 7=2926J

Calculate number of mole (Mg)= 0.427/24=0.01779

Energy change=2926/0.01779=164.47kJ/mol

[starburst.95]

awesome. Thanks heaps!