When 0.250 moles of KCl are added to 200.0 g of water in a constant pressure calorimeter a temperature change is observed. Given that the specific heat of the resulting solution is 4.184 J g-1 °C-1, the molar heat of solution of KCl is +17.24 kJ/mol, and that we can ignore the small amount of energy absorbed by the calorimeter, the observed temperature change should be Entry field with incorrect answer now contains modified data °C.

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OlaMacgregor OlaMacgregor · Answer 1 · 2019-10-24T08:08:00+02:00

Explanation:

Upon dissolution of KCl heat is generated and temperature of the solution raises.

Therefore, heat generated by dissolving 0.25 moles of KCl will be as follows.

[tex]17.24 kJ/mol \times 0.25 mol[/tex]

= 4.31 kJ

or, = 4310 J (as 1 kJ = 1000 J)

Mass of solution will be the sum of mass of water and mass of KCl.

Mass of Solution = mass of water + (no. of moles of KCl × molar mass)

= 200 g + [tex](0.25 mol \times 54.5 g/mol)[/tex]

= 200 g + 13.625 g

= 213.625 g

Relation between heat, mass and change in temperature is as follows.

Q = [tex]mC \Delta T[/tex]

where, C = specific heat of water = [tex]4.184 J/g^{o}C[/tex]

Therefore, putting the given values into the above formula as follows.

Q = [tex]mC \Delta T[/tex]

4310 J = [tex]213.625 g \times 4.184 J/g^{o}C \times \Delta T[/tex]

[tex]\Delta T = 4.82^{o}C[/tex]

Thus, we can conclude that rise in temperature will be [tex]4.82^{o}C[/tex].