When 10.0 g of KOH is dissolved in 100.0 g of water in a coffee-cup calorimeter,the temperature rises from 25.18 °C to 47.53 °C.What is the enthalpy change per gram of KOH dissolved in the water? Assume that the solution has a specific heat capacity of 4.18 J/g ⋅ K.

Question

Quizplus · Accepted Answer

First, we need to calculate the amount of heat absorbed by the solution:

q = m x c x ∆T

q = (100.0 g + 10.0 g) x 4.18 J/g ⋅ K x (47.53 °C - 25.18 °C)

q = 6111.96 J

Next, we need to calculate the amount of heat absorbed per gram of KOH:

- For 10.0 g of KOH, the amount of heat absorbed is:

q1 = 6111.96 J

- Therefore, for 1.0 g of KOH, the amount of heat absorbed is:

q2 = q1 / 10.0 g

q2 = 611.196 J/g

Finally, we need to calculate the enthalpy change per gram of KOH:

∆H = q2 / 1.0 g

∆H = -1.03 × 10¹³ J/g (Note: negative sign indicates an exothermic reaction)

Therefore, the best choice is C.

When 100 G of KOH Is Dissolved in 100