Recent questions in Chemistry

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:

asked Nov 15, 2013 by mosymeow_1

1 answer

$ 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:

asked Nov 15, 2013 by mosymeow_1

1 answer

$A + B \rightleftharpoons C + D$ 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:

asked Nov 15, 2013 by mosymeow_1

1 answer

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?

asked Nov 15, 2013 by mosymeow_1

1 answer

$ 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

asked Nov 15, 2013 by mosymeow_1

1 answer

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:

asked Nov 15, 2013 by mosymeow_1

1 answer

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

asked Nov 15, 2013 by mosymeow_1

1 answer

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) :

asked Nov 15, 2013 by mosymeow_1

1 answer

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:

asked Nov 15, 2013 by mosymeow_1

1 answer

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:

asked Nov 15, 2013 by mosymeow_1

1 answer

What is the Equilibrium constant for the formation of one mole of gaseous $HI$ from the $H_2(g)$ and $I_2(g)$?

asked Nov 15, 2013 by mosymeow_1

1 answer

What are the units of Equilibrium equations $K_p$ and $K_c$ when $\Delta n_g < 0$ respectively ?

asked Nov 15, 2013 by mosymeow_1

1 answer

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} [?]$

asked Nov 15, 2013 by mosymeow_1

1 answer

Which of the following is incorrect about relationship between $K_p$ and $K_c$?

asked Nov 15, 2013 by mosymeow_1

1 answer

Which of the following dashed line represents the position at equilibrium for the concentration-time plot of a reaction??

asked Nov 15, 2013 by mosymeow_1

2 answers

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?

asked Nov 13, 2013 by mosymeow_1

1 answer

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

asked Nov 13, 2013 by mosymeow_1

1 answer

The equilibrium constant for the reaction $CaSO_4.5H_2O (s) \rightleftharpoons CaSO_4.3H_2O (s) + 2H_2O (g)$ is equal to

asked Nov 13, 2013 by mosymeow_1

1 answer

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

asked Nov 13, 2013 by mosymeow_1

1 answer

Specify the unit of Equlibrium Constant of the following reaction. $ Fe^{3+} (aq) + SCN^- (aq) \rightleftharpoons Fe(SCN)^{2+} (aq) $

asked Nov 13, 2013 by mosymeow_1

1 answer

Why does the solubilities of anhydrous salts decrease with increase in temperature?

asked Nov 13, 2013 by mosymeow_1

1 answer

Which of the following can exist beyond critical temperature and critical pressure?

asked Nov 13, 2013 by mosymeow_1

1 answer

What happens to a solid whose vapour pressure reaches 760 mm Hg at temperatures which are lower than the triple point?

asked Nov 13, 2013 by mosymeow_1

1 answer

At the boiling point of a liquid its ________ becomes equal to the atmospheric pressure.

asked Nov 13, 2013 by mosymeow_1

1 answer

As melting of ice is an _ process, supplying heat to the system shifts the equilibrium in the direction and viceversa.

asked Nov 13, 2013 by mosymeow_1

1 answer

A solid mixture 5g consists of lead nitrate and sodium nitrate was heated below $600^{\large\circ}C$ until weight of residue was conotaut.If the loss in weight is 28%,find the amount of lead nitrate and sodium nitrate mixture.

asked Nov 6, 2013 by sreemathi.v

1 answer

Gastric juice contains 3.0g of HCl per litre.If a person produces 2.5l of gastric juice per day,how many antacid tablets each containing 400mg of $Al(OH)_3$ are needed to neutralized all the HCl produced in one day ?

asked Nov 6, 2013 by sreemathi.v

1 answer

How many ml of 0.1N HCl are required to react completely with 1g mixture of $Na_2CO_3$ and $NaHCO_3$ containing equimolar amount of two ?

asked Nov 6, 2013 by sreemathi.v

1 answer

0.5g of a mixture of $K_2CO_3$ and $Li_2CO_3$ required 30ml of 0.25N HCl solution for neutralization.What is % composition mixture ?

asked Nov 6, 2013 by sreemathi.v

1 answer

$0.05\;g$ of a commercial sample $KCl_3$ on decomposition liberated just sufficient oxygen for complete oxidation of $20\;ml\; CO$ at $27^{\large\circ}C$ and $750\;mm$ pressure.Calculate % of $KClO_3$ in sample.

asked Nov 6, 2013 by sreemathi.v

1 answer

$8.0575\times 10^{-2}kg$ of Glauber's salt is dissolved in water.Obtain $1clm^3$ of a solution of density $1077.2kgm^{-3}$.Calculate the molarity and the mole fraction of $Na_2SO_4$ in solution .

asked Nov 6, 2013 by sreemathi.v

1 answer

0.22g sample of volatile compound,containing $C,H$ and $Cl$ only on combustion in $O_2$ gave 0.195g $CO_2$ and 0.0804g $H_2O$.If 0.120g of the compound occupied a volume of 37.24ml at $105^{\large\circ}$ and 768mm of pressure,calculate molecular formula of compound.

asked Nov 6, 2013 by sreemathi.v

1 answer

A mixture in which the mole ratio of $H_2$ and $O_2$ is 2 : 1 is used to prepare water by the reaction $2H_2(g)+O_2(g)\rightarrow 2H_2O(g)$.The total pressure in the container is 0.8atm at $20^{\large\circ}C$ before the reaction.Determine the final pressure at $120^{\large\circ}C$ after reaction assuming 80% yield of water.

asked Nov 6, 2013 by sreemathi.v

1 answer

A gas mixture of $3l$ of propane $(C_3H_8)$ and butane $C_4H_{10}$ on complete combustion at $25C^{\large\circ}$ produced $10l$ $CO_2$.Find out the composition of gas mixture.

asked Nov 6, 2013 by sreemathi.v

1 answer

n-Butane is produced by the monobromination of ethane followed by word reaction .Calculate the volume of ethane at NTP to produce 55g n-butane if the bromination takes place with 90% yield and worth reaction with 85% yield.

asked Nov 6, 2013 by sreemathi.v

1 answer

For the reaction ,$N_2O_5(g)\iff 2NO_2(g)+0.5O_2(g)$.Calculate the mole fraction of $N_2O_5(g)$ decomposed at a constant volume and temperature,if the initial pressure at any time is 960mm Hg.Assume ideal gas behaviour.

asked Nov 6, 2013 by sreemathi.v

1 answer

A sample of Mg was burnt in air to give a mixture of MgO and $Mg_3N_2$.The ash was dissolved in 60meq. of HCl and the resulting solution was back titrated with NaOH.12meq of NaOH were required to reach the end point.An excess of NaOH was added and the solution distilled.The ammonia released was then trapped in 10Meq of second acid solution .Back titration of this solution required 6Meq of the base.Calculate the percentage of Mg burnt to the nitride.

asked Nov 6, 2013 by sreemathi.v

1 answer

A mixture of $HCOOH$ and $H_2C_2O_4$ is heated with Conc.$H_2SO_4$.The gas produced is collected and on treating with KOH solution the volume of the gas decreases by $\large\frac{1}{6}$th.Calculate molar ratio of two acids in original mixture.

asked Oct 31, 2013 by sreemathi.v

1 answer

What would be the molality of a solution obtained by mixing equal volumes of 30% by weight $H_2SO_4$ ($d=1.218gml^{-1}$) and 70% by weight $H_2SO_4$ ($d=1.610gml^{-1}$)?If the resulting solution has density 1.425g/ml,calculate its molarity.

asked Oct 31, 2013 by sreemathi.v

1 answer

The vapour density of a mixture containing $NO_2$ and $N_2O_4$ is 38.3 at $27^{\large\circ}C$.Calculate the mole of $NO_2$ in 100g mixture

asked Oct 31, 2013 by sreemathi.v

1 answer

To 50litre of 0.2N NaOH ,5litre of 1N HCl and 15litre of 0.1N $FeCl_3$ solution are added .What weight of $Fe_2O_3$ can be obtained from the precipitate?Also report the normality of NaOH left in the resultant solution.

asked Oct 31, 2013 by sreemathi.v

1 answer

Calculate molarity of water $(d_{H_2O}=1gml^{-1})$

asked Oct 31, 2013 by sreemathi.v

1 answer

Calculate molality of 1L solution of 93% $H_2SO_4$ by volume .The density of solution is 1.84g/ml

asked Oct 31, 2013 by sreemathi.v

1 answer

What is the purity of conc $H_2SO_4$ solution (specific gravity 1.8g/ml),if 5ml of this solution is neutralized by 84.6ml of $2.0N\;NaOH$

asked Oct 31, 2013 by sreemathi.v

1 answer

What volume at NTP of ammonia gas will be required to be passed into 30ml of $NH_2SO_4$ solution to bring down the acid normality to 0.2N

asked Oct 31, 2013 by sreemathi.v

1 answer

Pottassium selenate is isomorphous with potassium sulphate and contains 45.42% selenium by weight.Calculate the atomic weight of selenium.Also report the equivalent weight of potassium selenate.

asked Oct 31, 2013 by sreemathi.v

1 answer

What volume of 0.20M $H_2SO_4$ is required to produce 34.0g of $H_2S$ by the reaction: $8KI+5H_2SO_4\rightarrow 4K_2SO_4+4I_2+H_2S+4H_2O$

asked Oct 31, 2013 by sreemathi.v

1 answer

20ml of 0.2M $Al_2(SO_4)_3$ is mixed with 20ml of 0.6M $BaCl_2$.Calculate the concentration of each ion in solution.

asked Oct 31, 2013 by sreemathi.v

1 answer

What volume of a solution of hydrochloric acid containing 73g of acid per litre would sufficient for the exact neutralization of sodium hydroxide obtained by allowing 0.46g of metallic sodium to act upon water ?

asked Oct 31, 2013 by sreemathi.v

1 answer

What volume of water is required to make 0.2N solution from 1600ml of 0.205N solution ?

asked Oct 31, 2013 by sreemathi.v

1 answer

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