A coffee cup calorimeter was used to measure the heat of reaction - the change i

Question

A coffee cup calorimeter was used to measure the heat of reaction - the change in enthalpy that occurs when a solid dissolves in water. A 10.0 g sample of an ionic compound with a molar mass of 175.0 g/mol was added to a sample of deionized water to produce 60.0 grams of solution. After stirring and dissolving the solid, the temperature was found to change from 25.00 °C to 23.75 °C. Calculate the enthalpy of reaction Hrxn, per mole of salt dissolved. Assume the specific heat of the solution is 4.10 J/(g·°C) and the heat capacity of the calorimeter is 4.80 J/°C.

Explanation / Answer

dH = Cpt x dT + mx Cx dT

Cpt =4.80J/oC

dT = 23.75oC -25 = -1.25oC

m = 60g

C= 4.10J/goC

dT = -1.25

So, dH = (4.8 x -1.25) + (60 x 4.1 x -1.25) = -6-307.5 = -313.5J

No. of moles present = mass taken/ molar mass = 10g/175g/mol = 0.057moles

so, dH per ,mol = -313.5/0.057 = -5486.25J/mol

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.