A student determines the heat of dissolution of solid
ammonium bromide using a coffee-cup calorimeter of
negligible heat capacity.
When 6.34 g of NH4Br(s) is dissolved in 119.00 g of water, the temperature of the solution drops from 25.00 to 22.76 °C. Based on the student's observation, calculate the enthalpy of dissolution of NH4Br(s) in kJ/mol. Assume the specific heat of the solution is 4.184 J/g°C.
ΔHdissolution = kJ/mol
no of moles of NH4Br = W/G.M.Wt
= 6.34/97.94 = 0.0647moles
mass of solution = 6.34+ 119 = 125.34g
q = mcT
ΔHdissolution = -1174.7J
= -1174.7/0.0647 = -18.156KJ/mole >>>>>answer
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