Download App

Equilibrium — Chemistry STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 ScienceChemistryEquilibrium5 Marks
Question
  1. The reaction quotient of a reversible reaction is $Q_C$ and the equilibrium constant is $K_c$. What do you conclude for the reaction if $Q_c < K_c$?
  2. State Le Chatelier's principle.
  3. In qualitative analysis, $NH_4Cl$ is added before adding $NH_4OH$ solution for testing of III group radicals [$Fe^{3+}, Cr^{3+}$ and $Al^{3+}$]. Explain by using concept of common ion effect.
✓

Answer

  1. If $Q_c < K_c$; the reaction tends towards forward direction to attain equilibrium.
  2. Le Chatelier's Principle: If a system in equilibrium is subjected to a change in concentration, temperature or pressure, the equilibrium shifts in a direction that tends to undo the effect of the change.
  3. Hydroxides of group III are precipitated by adding $NH_4OH$ in presence of $NH_4Cl$. The role of $NH_4Cl$ is to produce common ion effect.
$\text{NH}_4\text{OH}\rightleftharpoons\text{NH}^+_4+\text{OH}^-$
$\text{NH}_4\text{Cl}\xrightarrow{ \ \ \ \ \ \ \ \ \ \ \ }\text{NH}_4^++\text{Cl}^-$
Due to common ion effect, the degree of dissociation of $NH_4OH$ is suppressed and less $OH^‑$ are formed. This less concentration of $OH^-$ is sufficient to precipitate group III cations but not the cations of higher groups since the $K_{sp}$ of group III < subsequent groups.

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "5 Marks Questions" from Equilibrium→Equilibrium — all question types→Chemistry STD 11 Science question papers→Gujarat Board STD 11 Science question papers→Gujarat Board question paper generator→

Similar questions

Define the octet rule and explain its limitations with examples.
→
Explain the nomenclature of organic compounds by common name system with examples.
→
Direction: Match Column I with Column II.
S. No.
Column I
S. No.
Column II
(a)
$\text{BF}^-_4$
(i)
Oxidation state of central atom is +4
(b)
$AlCl_3$
(ii)
Strong oxidising agent
(c)
$SnO$
(iii)
Lewis acid
(d)
$PbO_2$
(iv)
Can be further oxidised
 
 
(v)
Tetrahedral shape
→
Discuss the pattern of variation in the oxidation states of,
  1. B to Tl.
  2. C to Pb.
→
The solubility product of $Al ( OH )_3$ is $2.7 \times 10^{-11}$. Calculate its solubility in $gL ^{-1}$ and also find out pH of this solution. (Atomic mass of $Al =27 u$ ).
→
Explain the following:
  1. Silicones are used for making water proof fabrics.
  2. Boron does not form $B^{3+}$ ion.
  3. Boric acid is considered as a weak acid.
  4. Carbon forms covalent compounds while lead forms ionic compounds.
  5. Graphite is used as a lubricant.
→
Calculate the enthalpy change for the process$\text{CCI}_4(\text{g})\xrightarrow{ \ \ \ \ \ }\text{C}(\text{g})+4\text{CI}(\text{g})$
and calculate bond enthalpy of $C – Cl$ in $CCl_4$(g).$\Delta_\text{vap}\text{H}^\ominus(\text{CCI}_4)=30.5\text{kJ} \ \text{mol}^{-1}.$
$\Delta_\text{f}\text{H}^\ominus(\text{CCI}_4)=-135.5\text{kJ} \ \text{mol}^{-1}.$
$\Delta_\text{a}\text{H}^\ominus(\text{C})=-715.0\text{kJ} \ \text{mol}^{-1},$ where $\Delta_\text{a}\text{H}^\ominus$ is enthalpy of atomisation
$\Delta_\text{a}\text{H}^\ominus(\text{CI}_2)=242\text{kJ} \ \text{mol}^{-1}$
→
Calculate (a) $\Delta \text{G}^\ominus$ (b) the equilibrium constant for the formation of $NO_2$ from NO and $O_2$​​​​​​​ at 298K
$\text{NO (g) + }1/2\text{ O}_2\text{ (g)}\rightleftharpoons\text{NO}_2\text{ (g)}$
where
$\Delta_\text{r}\text{G}^\ominus\text{ (NO}_2)=52.0\text{ kJ/mol}$
$\Delta_\text{r}\text{G}^\ominus\text{ (NO})=87.0\text{ kJ/mol}$
$\Delta_\text{r}\text{G}^\ominus\text{ (O}_2)=0\text{ kJ/mol}$
→
Calculate the equilibrium constant for the following equilibrium system at 1120K. $\text{C}(\text{s})+\text{CO}_2(\text{g})+2\text{Cl}_2\stackrel{\text{K}_\text{p}}{\rightleftharpoons}2\text{COCl}_2(\text{g})$ Given the following equations and equilibrium constants: $\text{CO}(\text{s})+\text{Cl}_2(\text{g})\rightleftharpoons\text{COCl}_2(\text{g})$ $\text{Kp}_1 = 6.0 \times 10-3 \dots(1)$ $\text{CO}(\text{s})+\text{Cl}_2(\text{g})\rightleftharpoons\text{CO}_2(\text{g})$$\text{Kp}_2 = 1.3 \times 1014 \dots(2)$
→
Derive the formula to find the ionization constant of weak acids and bases and how will you obtain the value of [H] to find their pH?
→