PART - 1 CH - 1 Some Basic Concepts of Chemistry — Chemistry STD 11 Science — Question

1. State Henry's Law.
2. Assign reason for the following:

1. A solution of NH₄Cl in water shows pH less than 7.
2. In qualitative analysis NH₄Cl is added before adding NH₄OH for testing Fe³⁺ or AP³⁺ ions.

3. Consider the reaction:

$\text{N}_2(\text{g})+3\text{H}_2(\text{g})\rightleftharpoons2\text{NH}_3+\text{Heat}$

Indicate the direction in which the equilibrium will shift when:

1. Temperature is increased.
2. Pressure is increased.

1. At 473K, equilibrium constant, K for decomposition of PCl₅ is 8.3 × 10^-3. If decomposition is depicted as

$\text{PCl}_5(\text{s})\rightleftharpoons\text{PCl}_3(\text{s})+\text{Cl}_2(\text{g});$

$\Delta_\text{r}\text{H}^\text{o}=124.0\text{kJ mol}^{-1}$

1. Write an expression for K_c for the reaction.
2. What is the value of K_c for the reverse reaction at same temperature.
3. What would be the effect on K_c if:

1. The pressure is increased?
2. The temperature is increased?

2. Write equilibrium constant for the following reactions:

1. $\text{BaCO}_3(\text{s})\rightleftharpoons\text{BaO(s)}+\text{CO}_2(\text{g})$

2. $\text{CH}_4(\text{g})+2\text{O}_2(\text{g})\rightleftharpoons\text{CO}_2(\text{g})+2\text{H}_2\text{O(g)}$