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The solubility of $A_2X_3$ is y mol $dm^{-3}$. Its solubility product is
answered Nov 27, 2013
Answer: $108 y^5$   $A_2X_3 \rightleftharpoons 2A^{3+} + 3X^{2-}$ At equilibri...
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Which of the following ionic species has the greatest protons affinity to form stable compound?
answered Nov 27, 2013
Toolbox:Strongest proton affinity will be for species which is the strongest base or whose conjugate...
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The $pK_a$ of weak acid (HA) is 4.5 . The $pOH$ of an aqueous buffered solution of HA in which 50% of acid is ionized is
answered Nov 27, 2013
Answer: 9.5   When HA is 50% ionised, [HA] = [$A^-$] $pH = PK_a + log \frac{[A...
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The $pH$ of a dilute solution of acetic acid was found to be 4.3. The addition of a small crystal of sodium acetate will cause $pH$ to
answered Nov 27, 2013
Answer: become more than 4.3   $CH_3COONa$ being strong electrolyte ionises into $...
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$\rho H$ of water is 7.0 at 298 K. If water is heated to 350 K, which of the following should be true?
answered Nov 27, 2013
Toolbox: Water undergoes self-dissociation, also referred to as self-ionization or autodis...
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A solution is obtained by mixing two solutions of same electrolyte with pH = 5 and pH = 3 respectively. The resulting solution has pH
answered Nov 27, 2013
Toolbox: $\rho H = - log [H^+]$ Answer: 3.3 If $\rho H = 5 H^+ = 10^{-\rho H} = 10^{-5}$ If...
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Degree of dissociation of an acid HCl is 95%. 0.192 g of the acid is present in 0.5 L of solution. The pH of the solution is
answered Nov 23, 2013
Toolbox: $\rho H = - log [H^+]$   Answer: 2   No. of moles o...
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At a certain temperature, the value of $\rho K_w$ is 13.4 and the measured $\rho H$ of a soltuion is 7. The solution is
answered Nov 23, 2013
Answer: basic   At this temperature the $\rho H$ of neutral solution will be 13.4 ...
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The pH of pure water at $80^\circ C$ will be
answered Nov 23, 2013
Answer: < 7   The value of $K_w$ increases with rise in temperature because dis...
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If the solubility of $Ag_2CrO_4$ is S mole/litre. Its solubility product is
answered Nov 23, 2013
Toolbox: Dissociation of an electrolyte, $A_xB_y \rightleftharpoons xA^{y+} + yB^{x-}$ Solubil...
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For the percipitation of cations of group four in the qualitative analysis, the medium is made alkaline before passing $H_2S$ gas. The purpose of alkaline Solution is
answered Nov 23, 2013
Answer: to increase the ionisation of $H_2S$   Dissociation of $H_2S$ $H_2S \r...
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$NH_4OH$ is a weak base but it becomes still weaker in the aqueous solution of
answered Nov 23, 2013
Toolbox:Common-ion effect describes the suppressing effect on ionization of an electrolyte when anot...
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Let the solubilities of AgCl in $H_2O$, 0.01 M $CaCl_2$, 0.01 M NaCl and 0.05 M $AgNO_3$ be $S_1, S_2, S_3 and S_4$ respectively. What is the correct relationship between these quantities?
answered Nov 23, 2013
Toolbox: Larger the concentrations of common ion, lesser will be the solubility. &...
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What is the decreasing order of strength of the bases $OH^-, NH_2^- , H-C\equiv C^-$ and $CH_3CH_2^-$ ?
answered Nov 23, 2013
Toolbox: A weak acid has a strong conjugate base. Answer: $CH_3CH_2^- > NH^-_2 ...
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Conjugate base of Hydrazoic acid is
answered Nov 23, 2013
Toolbox: Acid $\longrightarrow$ Proton + Conjugate base   Answer: $N_3^{-...
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In which of the following reactions does $NH_3$ acts as an acid?
answered Nov 23, 2013
Toolbox: Metals react with acids to liberate hydrogen gas.   Answer: $NH_...
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Which of the following can act both as a Bronsted acid and a Bronsted base?
answered Nov 23, 2013
Toolbox: Acid is a substance which is capable of donating a proton. Base is a substa...
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Which of the following is a Lewis acid?
answered Nov 23, 2013
Answer: $SnCl_4$ $SnCl_4$ acts as a lewis acid due to presence of vacant d-orbitals.
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According to the Lewis acid-base concept
answered Nov 23, 2013
Toolbox: Lewis' theory used electrons instead of proton transfer and specifically stated that an ...
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Which equilibrium can be described as an acid-base reaction using Lewis acid-base definition but not using Bronsted and Lowry concept?
answered Nov 23, 2013
Answer: $NH_3$   $NH_3$ is a donor and $Cu^{2+}$ ion is acceptor. Hence, $NH_3...
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Which one of the following is a Bronsted acid but not a Bronsted base?
answered Nov 23, 2013
Bronsted base are compounds which accept $H^+$ ions.Bronsted acid are compounds which donate $H^+$ i...
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When ammonia is added to pure water, the concentration of which of the following species already present, will decrease
answered Nov 23, 2013
Answer: $H_3O^+$   In pure water, there is an equilibrium $H_2O + H_2O \rightl...
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What is the Equilibrium constant for the formation of one mole of gaseous $HI$ from the $H_2(g)$ and $I_2(g)$?
answered Nov 23, 2013
Toolbox: For a reversible reaction, at equilibrium, Rate of Forward reaction = Rate of Backward r...
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The equilibrium constant $K_c$ for the reaction of $H_2$ with $I_2$ is 57.0 at 700 K $ H_2(g) + I_2(g) \rightleftharpoons 2HI $; $K_c$ = 57 at 700K. select correct statement:
answered Nov 23, 2013
Toolbox: Rate of reaction = Equilibrium Constant $\times$ Product of concentration of reac...
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For the following gaseous equilibria X, Y and Z at 300 K. $X: 2SO_2 + O_2 \rightleftharpoons 2SO_3$ $Y: PCl_5 \rightleftharpoons PCl_3 + Cl_2$ $Z: 2HI \rightleftharpoons H_2 + I_2$ ratio of $K_p$ and $K_c$ in the increasing order is:
answered Nov 23, 2013
Toolbox: Equilibrium constant determined from the partial pressures is $K_p = K_c (RT)^{\D...
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If $\beta_1, \beta_2$ and $\beta_3$ are stepwise formation constants of $MCl, MCl_2, MCl_3$ and K is the overall formation constants of $MCl_3$, then (charges ommitted) :
answered Nov 23, 2013
Answer: $log K = log \beta_1 + log \beta_2 + log \beta_3$   Given,   ...
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Given a reaction $ A + B \rightleftharpoons C + D $ taking place in a 1L vessel. If we start with 1 mole each of A and B, equilibrium concentration of [C] = [D] = 0.5 M. Percentage of A converted into C if we start with 2 moles of A and 1 mole of B, is
answered Nov 23, 2013
Answer: 33.33%   In first case,   A + B $\rightleftharpoons$ C + D ...
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We know that equilibrium constant, K changes with temperature. At 300K, equilibrium constant is 25 and at 400K it is 10. Hence, backward reaction will have energy of activation:
answered Nov 20, 2013
Toolbox: Van't Hoff equation: $log\frac{K_2}{K_1} = \frac{\Delta H}{2.303 \times R} [\frac...
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$ I_2 + I^- \rightleftharpoons I^-_3 $ This reaction is set-up in aqueous medium. Initially we have 1 mole of $I_2$ and 0.5 mole of $I^-$ in 1 L flask. After equilibrium is reached, excess of $AgNO_3$ gave 0.25 mole of yellow ppt. Equilibrium constant is
answered Nov 20, 2013
Answer: 1.33   The reaction given, $I_2 + I^- \rightleftharpoons I^-_3$ 1M...
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Volume of the flask in which species are transferred is double of the earlier flask. In which of the following reversible reactions, equilibrium will be shifted in the forward direction?
answered Nov 16, 2013
Answer: $ PCl_5 (g) \rightleftharpoons PCl_3 (g) + Cl_2 (g) $   As the volume is ...
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$A + B \rightleftharpoons C + D$ One mole each of A and B and 3 moles each of C and D are placed in 1L flask, if equilibrium constant is 2.25. Equilibrium concentrations of A and C will be in the ratio:
answered Nov 16, 2013
Answer: 2 : 3   $ A + B \rightleftharpoons C + D $ 1___1____3___3   at t=...
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$ Solute + H_2O \rightleftharpoons solution; \Delta H=\pm x $ For the given equation, Solubility(S) of a solute in the solvent (say $H_2O$) is given by $S = A e^{-\frac{\Delta H}{RT}}$ For a given solution, variation of log S with temperature is shown graphically. Hence, Solute is:
answered Nov 16, 2013
Answer: CaO   Given, Solubility(S) of a solute in a solvent, $ S = A e^{\frac{...
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For the reversible reaction equilibrium is $ N_2(g) + O_2(g) \overset{\overset{k_r}{\rightleftharpoons}}{_{k_f}} 2NO(g), $ $C_0 = Ce^{-2.1 \times 10^{-3} t} $ for the forward reaction and $C'_0 = C'e^{-4.2 \times 10^{-4}} t$ for the backward reaction, hence, if both forward and backward reactions are first order reactions then $K_c$ for the above equilibrium is:
answered Nov 16, 2013
Toolbox: For a first order reaction, $ k = \frac{1}{t} log_e\frac{C_0}{C} $  ...
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For a very small extent of dissociation of $PCl_5(g) \rightleftharpoons PCl_3(g) + Cl_2(g)$ is a gaseous phase reaction then degree of dissociation, x:
answered Nov 16, 2013
Answer: $ x \propto \sqrt{\frac{1}{P}} $   $ PCl_5 \rightleftharpoons PCl_3 + Cl_2 $ &n...
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Given $NaSO_4.10H_2O (s) \rightleftharpoons NaSO_4 (s) + 10H_2O (g) ; K_p =4.08 \times 10^{-25} $ and vapour pressure of water at $0^\circ$C = 4.58 Torr. At what relative humidity will $Na_2SO_4$ be deliquescent when exposed to the air at $0^\circ$C ?
answered Nov 16, 2013
Answer: (b) above 60.5%   $ Na_2SO_4.10H_2O(s) \rightleftharpoons Na_2SO_4(s) + 10...
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$PCl_5(g) \rightleftharpoons PCl_3(g) + Cl_2 (g)$ In the dissociation of $PCl_5, x $ varies with $\frac{D}{d}$ according to:
answered Nov 16, 2013
Answer:   Since, Degree of Dissociation or association = $\frac{\text...
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For the equilibrium $2SO_2 + O_2 \rightleftharpoons 2SO_3$ we start with 2 moles of $SO_2$ and 1 mole of $O_2$ at 3 atm. When equilibrium is attained, pressure changes to 2.5 atm. Hence, $K_p$ is:
answered Nov 15, 2013
Toolbox: PV=nRT   Answer: 2 $atm^{-1}$   Initiallly, P= 3 atm T...
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What are the units of Equilibrium equations $K_p$ and $K_c$ when $\Delta n_g < 0$ respectively ?
answered Nov 15, 2013
Toolbox: $ K_p = K_c (RT)^{\Delta n_g} $   Answer: $(atm)^{\Delta n_g} $,...
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what would be the expression in place of ? in the Van't Hoff equation: $ log \frac{K_2}{K_1} = \frac {\Delta H^\circ}{2.303R} [?]$
answered Nov 15, 2013
Toolbox: The Vant Hoff equation is: $ \frac{d ln K_p}{dT} = \frac {- \Delta H^\circ}{T^2} ...
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Which of the following is incorrect about relationship between $K_p$ and $K_c$?
answered Nov 15, 2013
Toolbox: $ K_p = K_c (RT)^{\Delta n_g} $   Answer: When, $\Delta n_g >...
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Which of the following dashed line represents the position at equilibrium for the concentration-time plot of a reaction??
answered Nov 15, 2013
Therefore, the dashed line C shows the position at which equilibrium is reached.
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For the reaction $ 2A(g) + B(g) \rightleftharpoons 3C(g) + 4D(g)$ Three moles each of $A$ and $B$ were taken into a $1\; L$ flask. which of the following is always true when the system attains equilibrium?
answered Nov 13, 2013
Answer: [A] < [B]   From the equation, it is clear that 2 moles of A combine wi...
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The equilibrium constant for the reaction $ A + 2B \rightleftharpoons 2C $ is 40. The Equilibrium constant for the reaction $ C \rightleftharpoons B + 1/2 A$ is
answered Nov 13, 2013
Toolbox: $ K' = \frac {1}{K} $   Answer: $[\frac{1}{40}]^{\frac{1}{2}} $ ...
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The equilibrium constant for the reaction $CaSO_4.5H_2O (s) \rightleftharpoons CaSO_4.3H_2O (s) + 2H_2O (g)$ is equal to
answered Nov 13, 2013
Answer: $[H_2O]^2$   $ K = \frac {[CaSO_4.3H_2O] [H_2O]^2} {[CaSO_4.5H_2O]} $ ...
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The equilibrium constant for a reaction; $ A+B \rightleftharpoons C+D $ is $ 1 \times 10^{-2} $ at 298 K is 2 at 373 K. The chemical process resulting in the formation of C and D is
answered Nov 13, 2013
On raising temperature K increases. It means the forward reaction is favoured on increasing tem...
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Specify the unit of Equlibrium Constant of the following reaction. $ Fe^{3+} (aq) + SCN^- (aq) \rightleftharpoons Fe(SCN)^{2+} (aq) $
answered Nov 13, 2013
$ Fe^{3+} (aq) + SCN^- (aq) \rightleftharpoons Fe(SCN)^{2+} (aq) $ K = $ \frac { [FeSCN^{2+...
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Which of the following expression acquires constant value at equilibrium for the process shown below?
answered Nov 13, 2013
Toolbox: In case of a $ Liquid \rightleftharpoons Gas $ equilibrium, the pressure of the v...
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Why does the solubilities of anhydrous salts decrease with increase in temperature?
answered Nov 13, 2013
Toolbox: Anhydrous salts which for hydrates (MgSO$_{4}$ , CuSO$_{4}$ etc..), almost all al...
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Which of the following can exist beyond critical temperature and critical pressure?
answered Nov 13, 2013
Toolbox: Liquid water cannot exist beyond 647.15 K and 218 atm pressure. These temperature and pr...
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What happens to a solid whose vapour pressure reaches 760 mm Hg at temperatures which are lower than the triple point?
answered Nov 13, 2013
Toolbox: Solid-Gas Equlibrium Only those solids sublime whose vapour pressure reaches 760 mm H...
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