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Chem homework help me please

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Tinga
Posts: 11349 - Karma: 2,333
alright so this may or may not be due in an hour please help
Consider the dissolution of CaCl2.

CaCl2(s) Ca2+(aq) + 2 Cl-(aq)      H = -81.5 kJ

A 13.2 g sample of CaCl2 is dissolved in 135 g of water, with both substances at 25.0°C. Calculate the final temperature of the solution assuming no heat lost to the surroundings and assuming the solution has a specific heat capacity of 4.18 J/°C·g.

can someone help me with the equation and the solution?
Nov 2 2007 11:09AM
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Boodje.
Posts: 1394 - Karma: 21
dood,im in school tolol. add the properties and multiply by the distrubute. then subtract c2.
Nov 2 2007 11:11AM
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Boodje.
Posts: 1394 - Karma: 21
no i dont know lol . but try going to PHSchool.com
Nov 2 2007 11:12AM
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bigdaddytmac
Posts: 1448 - Karma: 14
Ok first 13.2g/111g per mol for CaCl2 gives you .119 mol of CaCl2 in the reaction. Next, consider the delta H given for only .119 mol of CaCl2 dissolving. This gives you an actual delta heat for your reaction of -9.699 kJ. Finally plug your numbers into the formula H=mCT.  -9.699 kJ=142.8g*4.18*T <---Solve for T. Be careful, the enthalpy change is in kiloJoules.
Nov 2 2007 11:35AM
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