Question

I have a quiz coming up for chemistry. On the study guide we need to know how to: Use Le Chatelier's principle to predict the effect of a change in concentration on the equilibrium position; Use Le Chatelier's principle and ∆n(gas) to predict the effect of a change in pressure (volume) on the equilibrium position; Use Le Chatelier's principle and ∆H° to predict the effect of a change in temperature on the equilibrium position and on K. I missed these lectures and I am having a hard time understanding how to do these three things. I also need help understanding how to tell strong acids and bases.

Answer 1

Effect of change in concentration on the equilibrium position:- consider the reaction A---> B

case1:- Increase in concentration of A results in increase in forward reaction.

case2:- Increase in concentration of B results in increase in backward reaction till the concentration of A and B attains the equilibrium.

Effect of pressure on th equilibrium position:-

consider the reaction N₂ + 3 H₂ ---> 2NH₃ (REVERSIBLE REACTION)

Increase in pressure speed up the forward reaction because number of mole of reactant is higher than the product and the equilibrium shift towards the fewer moles of gas.

Effect of delta H on equilibrium position:-

case1: if the reaction is endothermic ( delta H = +ve)

delta H =H(product) - H(reactant) increase in temperature shifts the equilibrium in forward direction. High temperature favours the reaction.

case2:- if the reaction is exothermic (delta H = -ve)

Increase in temperature shifts the reaction backward. Here temperature is released during the reaction, indicates that the reaction shifts towards forward direction under low temperature.

Strong acids:- acid strength refers to the tendency of an acid to dissociate into a proton and anion.

strong acids are:- HCl,HBr,HI,H₂S0₄, HNO₃, HClO₃,HClO₄

Strong bases:- Strong base is a base completely dissociated in an aqueous solution.

example:- KOH,NaOH, Ba(OH)₂