Problem: Potassium nitrate, KNO3, has a molar mass of 101.1 g/mol. In a constant-pressure calorimeter, 32.3 g of KNO3 is dissolved in 243 g of water at 23.00 °C.KNO3(s)+H2O(aq) →  KOH(aq)+HNO3(aq)The temperature of the resulting solution decreases to 17.90 °C. Assume the resulting solution has the same specific heat as water, 4.184 J/(g·°C), and that there is negligible heat loss to the surroundings.1. How much heat was released by the solution?2. What is the enthalpy of the reaction?

FREE Expert Solution
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FREE Expert Solution

Calculate the amount of heat released in the reaction


 qsystem = qsolution + qreaction


• Since no heat is lost to the surroundings: qsystem = 0


qsolution + qreaction­ = 0 qreaction­ = - qsolution




The heat (q) of the solution can be calculated using:


qsoln = mcT

Where

m is the mass of the solution

c is the specific heat of water (4.1801 J/g-k)

∆T is the change in temperature (Tfinal - Tinitial)



87% (113 ratings)
Problem Details

Potassium nitrate, KNO3, has a molar mass of 101.1 g/mol. In a constant-pressure calorimeter, 32.3 g of KNO3 is dissolved in 243 g of water at 23.00 °C.

KNO3(s)+H2O(aq) →  KOH(aq)+HNO3(aq)

The temperature of the resulting solution decreases to 17.90 °C. Assume the resulting solution has the same specific heat as water, 4.184 J/(g·°C), and that there is negligible heat loss to the surroundings.

1. How much heat was released by the solution?

2. What is the enthalpy of the reaction?

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