1. predict the effect that decreasing pressure would have on each of the following reaction systems at equilibrium. a) h₂(g) + ci₂(g) ⇄ 2hci(g) b) 3o₂(g)⇄ 2o₃(g) c) caco₃(s) ⇄ cao(s) + co₂(g) 2. identify the following salt solutions as acidic, basic, or neutral. a) 0.5 m nacl b) 0.1 m nh₄no₃ c) 0.25 m ca(ch₃coo)₂

Answers:

1. a) Nothing; b) position of equilibrium moves to left; c) position of equilibrium moves to the right.

2. a) Neutral; b) acidic; c) basic.

Explanation :

1. Le Châtelier’s Principle states that if you apply a stress to a system at equilibrium the system will respond in a way that will reduce the stress.

Here, the stress is the reduction of pressure. So the system will respond is a way that increased the pressure. That is, it will produce more moles of gas.

a) H₂(g) + Cl₂(g) ⇌ 2HCl(g)

Thee are two moles of gas on each side of the equation. Nothing the system does will increase the pressure, so nothing will happen.

b) 3O₂(g) ⇌ 2O₃(g)

There are more moles of gas on the left, so the position of equilibrium will move to the left.

c) CaCO₃(s) ⇌ CaO(s) + CO₂(g).  

There are more moles of gas on the right, so the position of equilibrium will move to the right.

2. The conjugate base of a strong acid is neutral.

The conjugate acid of a strong base is neutral.

The conjugate base of a weak acid is basic.

The conjugate acid of a weak base is acidic.

a) NaCl

Salt of strong acid (HCl) and strong base (NaOH). Both ions are neutral.

b) NH₄NO₃

Salt of strong acid (HNO₃) and weak base (NH₃). NH₄⁺ is acidic.

c) (CH₃COO)₂Ca

Salt of weak acid (CH₃COOH) and strong base [Ca(OH)₂]. CH₃COO⁻ is basic.