Page 30 - Pharmaceutical_Analytical_Chemistry_1_Theoretical_Notes_Level_1

Mansoura National University
Pharm D-Clinical Pharmacy Program Level 1 Pharm. Anal. Chem. 1 (PC 101)

1. Effect of temperature

➢ Adding energy shifts the equilibrium ➢ Adding energy shifts the equilibrium
to the right. (away from the heat side). to the left. (away from the heat side).

2. Effect of pressure

▪ Pressure influences equilibrium only if one or more of the substances involved is a gas.

▪ Increasing the pressure shifts the equilibrium in the direction that decreases the

number of moles in the gas phase and thus decreases the pressure.

Ex: In ammonia synthesis

N (g) + 3H (g)  2 NH (g)
2 2 3

4 moles of gas 2 moles of gas

➢ Increasing the pressure causes the equilibrium to shift to the right.
➢ Example 2:

H2 + I2  2 HI
1 mole 1 mole 2 moles
(no shift occurs upon increasing pressure since no change in the total no of moles occurs).

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