A calorimeter contains 28.0 mL of water at 11.5 ∘C∘C . When 2.20 gg of XX (a substance with a molar mass of 77.0 g/mol )

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A calorimeter contains 28.0 mL of water at11.5 ∘C∘C . When 2.20 gg of XX (asubstance with a molar mass of 77.0 g/mol ) is added, itdissolves via the reaction
X(s)+H2O(l)→X(aq)X(s)+H2O(l)→X(aq)
and the temperature of the solution increases to29.5 ∘C∘C .
Calculate the enthalpy change, ΔHΔHDelta H, for thisreaction per mole of XX.
A calorimeter is an insulated device in which a chemicalreaction is contained. By measuring the temperaturechange, ΔTΔTDelta T, we can calculate the heat released orabsorbed during the reaction using the following equation:
q=specific heat×mass×ΔTq=specific heat×mass×ΔT
Or, if the calorimeter has a predetermined heatcapacity, CCC, the equation becomes
q=C×ΔTq=C×ΔT
At constant pressure, the enthalpy change for thereaction, ΔHΔHDelta H, is equal to the heat, qpqpq_p;that is,
ΔH=qpΔH=qp
but it is usually expressed per mole of reactant and with a signopposite to that of qqq for the surroundings. The totalinternal energy change, ΔEΔEDelta E (sometimes referredto as ΔUΔUDelta U), is the sum of heat, qqq, and workdone, www:
ΔE=q+wΔE=q+w
However, at constant volume (as with a bombcalorimeter) w=0w=0 and so ΔE=qvΔE=qv.
Assume that the specific heat of the resulting solution is equalto that of water [4.18 J/(g⋅∘C)J/(g⋅∘C)], that densityof water is 1.00 g/mLg/mL, and that no heat is lost to thecalorimeter itself, nor to the surroundings.
Express the change in enthalpy in kilojoules per mole to threesignificant figures.