The heat of solution is defined as the difference in enthalpy between the dissolving material and a solvent under constant pressure, resulting in infinite dilution. When the solute is dissolved in the solvent, the enthalpy change is detected, which is referred to as heat dissolution or heat of solution. It is equal to the product of mass, temperature change and specific heat of the solvent. It is denoted by the symbol ΔH. Its standard unit of measurement is KJ/mol.
Formula
ΔH = m × ΔT × S
where,
ΔH is the heat of solution,
m is the mass of solvent,
ΔT is the change in temperature,
S is the specific heat of solvent.
Sample Problems
Problem 1. Calculate the heat of solution when a hydrated salt is dissolved in water at 300 K and rate of 43 KJ/mol. The specific heat of water is 0.004184 kJ/g∘C.
Solution:
We have,
m = 43
T = 300
S = 0.004184
Using the formula we have,
ΔH = m × ΔT × S
= 43 × 300 × 0.004184
= 53.97 KJ/mol
Problem 2. Calculate the heat of solution when a hydrated salt is dissolved in water at 250 K and rate of 65 KJ/mol. The specific heat of water is 0.004184 kJ/g∘C.
Solution:
We have,
m = 65
T = 250
S = 0.004184
Using the formula we have,
ΔH = m × ΔT × S
= 65 × 250 × 0.004184
= 68 KJ/mol
Problem 3. Calculate the heat of solution when a hydrated salt is dissolved in a solvent at 150 K and rate of 20 KJ/mol. The specific heat of solvent is 0.062 kJ/g∘C.
Solution:
We have,
m = 20
T = 150
S = 0.062
Using the formula we have,
ΔH = m × ΔT × S
= 20 × 150 × 0.062
= 186 KJ/mol
Problem 4. Calculate the mass of solvent when a hydrated salt is dissolved in it at a heat of solution 150 KJ/mol and 100 K. The specific heat of solvent is 0.165 kJ/g∘C.
Solution:
We have,
ΔH = 150
T = 100
S = 0.165
Using the formula we have,
ΔH = m × ΔT × S
=> 150 = m × 100 × 0.165
=> m = 150/16.5
=> m = 9.09 KJ
Problem 5. Calculate the mass of solvent when a hydrated salt is dissolved in it at a heat of solution 450 KJ/mol and 500 K. The specific heat of solvent is 0.542 kJ/g∘C.
Solution:
We have,
ΔH = 450
T = 500
S = 0.542
Using the formula we have,
ΔH = m × ΔT × S
=> 450 = m × 500 × 0.542
=> m = 450/271
=> m = 1.66 KJ
Problem 6. Calculate the temperature change for solvent when a hydrated salt is dissolved in it at a heat of solution 170 KJ/mol and rate of 70 KJ per mole. The specific heat of solvent is 0.004 kJ/g∘C.
Solution:
We have,
ΔH = 170
m = 70
S = 0.004
Using the formula we have,
ΔH = m × ΔT × S
=> 170 = 70 × ΔT × 0.004
=> ΔT = 170/0.28
=> ΔT = 607 K
Problem 7. Calculate the temperature change for solvent when a hydrated salt is dissolved in it at a heat of solution 600 KJ/mol and rate of 120 KJ per mole. The specific heat of solvent is 0.076 kJ/g∘C.
Solution:
We have,
ΔH = 600
m = 120
S = 0.076
Using the formula we have,
ΔH = m × ΔT × S
=> 600 = 120 × ΔT × 0.076
=> ΔT = 600/9.12
=> ΔT = 65.78 K
Similar Reads
Heat of Reaction Formula The heat of reaction, also known as the Enthalpy of Reaction, is the difference in the enthalpy value of a chemical reaction under constant pressure. It is the thermodynamic unit of measurement used to determine the total amount of energy produced or released per mole in a reaction. As a result, the
7 min read
Heat of Vaporization Formula The amount of heat that must be absorbed at a fixed temperature to evaporate a specific amount of liquid is called the heat of vaporization. When the velocity of the steam and the energy of motion of the fluid are matched, the velocity of the vapor is shown to be greater. To put it another way, the
2 min read
Heat Load Formula The heat load is the amount of heat energy that is expected to be injected into a specific space in order to keep the temperature within an acceptable range. The heat load is equal to the product of mass flow rate, specific heat constant and change in temperature. It is denoted by the symbol Q. Its
4 min read
Heat Loss Formula Heat can be termed as the quantity of energy that flows spontaneously between two objects due to a temperature differential. During thermal systems, objects with different temperatures tend to approach thermal equilibrium. The hotter object transmits heat to the colder object until the temperatures
4 min read
Heat Index Formula In shaded locations, the heat index is a temperature that combines air temperature and relative humidity. Perspiration or sweating is a natural way for the human body to cool down. Sweat evaporation is responsible for removing heat from the body. High relative humidity, on the other hand, slows evap
6 min read