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?

1. Qsol = -5.87 kJ

2. ΔHrn = 18.4 kJ/mol

Explanation:

According to the law of conservation of energy, the sum of the heat absorbed by the reaction and the heat released by the solution is zero.

Qrn + Qsol = 0

Qrn = -Qsol

We can calculate the heat released by the solution using the following expression.

Qsol = c . m . ΔT

where,

c: specific heat capacity of the solution

m: mass of the solution

ΔT: change in the temperature

Qsol = (4.184 J/g.°C) . (243g + 32.3g) . (17.90°C-23.00°C) = -5.87 × 10³ J = -5.87 kJ

The heat absorbed by the reaction is:

Qrn = -Qsol = 5.87 kJ

In the balanced equation, we have 1 mole of KNO₃. Given we are in a constant-pressure calorimeter, the enthalpy of reaction (per mole of KNO₃) is:

definition

                    entropy is a measure of the randomness or the extent of disorder of a chemical process.

                      enthalpy is a measure of the heat change of a reaction occurring at a constant pressure.

measurement units:

                        entropy is measured in joule per kelvin (jk⁻¹)   whereas enthalpy is measured in joule per mole (jmol⁻¹)

requirements:

                            entropy has no requirements or limits, and its change is measured by the division between the heat change of the chemical process and the temperature.

                              in contrast, enthalpy can only be related to the heat change of the reaction under standard conditions.