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Chemistry enthalpy help

Hi, how would i go about solving this problem:
Zinc will displace copper from copper (II) sulphate solution according to the following equation:
CuSO4(aq) + Zn(s) ? Cu(s) + ZnSO4(aq)
If an excess of zinc powder is added to 50 cm3 of 1.0 moldm-3 copper(II) sulphate, the temperature increases by 6.3 oC. Calculate the enthalpy change for the reaction.

Thanks
Reply 1
Original post by waqar_lfc
Hi, how would i go about solving this problem:
Zinc will displace copper from copper (II) sulphate solution according to the following equation:
CuSO4(aq) + Zn(s) ? Cu(s) + ZnSO4(aq)
If an excess of zinc powder is added to 50 cm3 of 1.0 moldm-3 copper(II) sulphate, the temperature increases by 6.3 oC. Calculate the enthalpy change for the reaction.

Thanks


use E=cm delta T
c=specific heat capacity of water
m= mass of water or in this case the 50cm^3 of copper sulphate
delta T=6.3
now number of moles of reactants can be found by using n=cv again with the copper sulphate.

finally use delta H=E/n to find the enthalpy change for the reaction
Reply 2
Hi how would i work this question, When 2.3 g of magnesium chloride dissolves in 200 cm3 of water, the temperature rose by 3.4 oC. Calculate the enthalpy change for the reaction.

Thanks
Reply 3
Original post by waqar_lfc
Hi how would i work this question, When 2.3 g of magnesium chloride dissolves in 200 cm3 of water, the temperature rose by 3.4 oC. Calculate the enthalpy change for the reaction.

Thanks


Use DeltaH=-(cm deltaT)/n
n=m/gfm to find the number of moles of magnesium chloride
c is again specific heat capacity of water
m= mass of water
deltaT=3.4degrees C
Reply 4
Thanks, really appreciate it :smile:
Reply 5
Hi, last question what If 50 cm3 of 1.0 moldm-3 NaOH is added to 25 cm3 of 2.0 moldm-3 CH3COOH, the temperature rose by 8.3 oC. Calculate the molar enthalpy change for the reaction.
Reply 6
Doesn't matter worked it out thanks.
Reply 7
Original post by waqar_lfc
Hi, last question what If 50 cm3 of 1.0 moldm-3 NaOH is added to 25 cm3 of 2.0 moldm-3 CH3COOH, the temperature rose by 8.3 oC. Calculate the molar enthalpy change for the reaction.


This is exactly the same sort of thing however you have to work out the number of moles of both the NaOH and the CH3COOH using n=cv. The smallest value will be the limiting factor so use that in your
deltaH=-(cm deltaT)/n equation
Reply 8
i dont understand how that works

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