MUNISH KAKAR's INSTITUTE OF CHEMISTRY
CONCENTRATION PRESENTATION ( WS # 8 )
Q1.
‘x’ g of water is mixed in 69 g of ethanol. Mole fraction of ethanol in the resulting solution
is 0.6. What is the value of ‘x’ ?
Q2.
Ans = 18 g
In solution of I2 and benzene, mole fraction of I2 is found to be 0.25. What is percentage by
mass of Iodine in given solution.
Q3.
Ans = 44.87% Iodine
A solution is prepared by dissolving 18.25 g of NaOH in distilled water to give 200 ml of
solution. Calculate the molarity of the solution.
Q4.
Ans = 2.28 M
An aqueous solution of KOH ( molecular mass : 56 ) contains 28% KOH by strength. What
is molarity of solution ?
Q5.
Ans : 5 M
An aqueous solution of CaO ( molecular mass : 56 )is found to contain 28% CaO by mass.
What is molality of solution ?
Q6.
Ans : 6.94 m
An aqueous solution of KOH ( molecular mass : 56 ) contains 28% KOH by mass. If
density of solution is, what is molarity of solution ?
Q7.
Ans : 5.3 M
An aqueous solution of CaO ( molecular mass : 56 )is found to contain 28% CaO by
strength. If density of solution is what is molality of solution ?
Q8.
The density of 3 molal solution of NaOH is 1.110 g mL -1. Calculate molarity of the
solution.
Q9.
Ans : 5.43 m
Ans = 2.97 M
How many mole and how many grams of sodium chloride are present in 250 mL of a 0.50
M NaCl solution ?
Ans = 0.125 mol, 7.3125 g
Q10. 0.63 g of oxalic acid, (COOH)2 2H2O are dissolved in 500 ml of solution. Calculate the
molarity of the solution ?
Ans = 0.01 M
Q11. How many moles of NaOH are contained in 27 mL of 0.15 M NaOH ? Ans = 0.00405 mol
Q12. Calculate the number of oxalic acid molecules in 100 ml of 0.01 M oxalic acid solution.
Ans = 6.023 × 1020
Q13. An aqueous solution of H2SO4 is found to contain 1.5 mole of H2SO4 in 1 L of solution,
what will be molality of solution? Given that density of solution is 1.4 g ml-1 Ans=1.197 m
Q14. If the density of methanol is 0.793 kgL-1, what is the volume needed for making 2.5 L of
its 0.25 M solution ?
Ans = 25.2 mL
Q15. A solution of oxalic acid, (COOH)2.2H2O is prepared by dissolving 0.63 g of the acid in 250
mL of the solution. Calculate
(i) molarity and
(ii) normality of the solution.
Ans = 0.02 M, 0.04 N
SCO # 203 , SECOND FLOOR , SECTOR - 14 , PANCHKULA ; 4634812 (O) , 9888019721 , 9988819721 1
MUNISH KAKAR's INSTITUTE OF CHEMISTRY
Q16. 2.82 g of glucose (molar mass = 180) are dissolved in 30 g of water. Calculate
(a) the molality
(b) mole fraction of glucose and water.
Ans = 0.522 m, 0.991.
Q17. A solution is 25% water, 25% ethanol and 50% acetic acid by mass. Calculate the mole
fraction of each component.
Ans = x w = 0.503, xE = 0.195, xA = 0.30
Q18. A given solution of NaOH contains 2.00 g of NaOH per litre of solution. Calculate the
molarity of this solution.
Ans = 0.05 M
Q19. 2.8 g of KOH is dissolved in water to give 200 cm3 of solution. Calculate the molarity of
KOH in the solution.
Ans = 0.25 M
Q20. How many gram of hydrogen chloride, HCl are required to prepare 4 litre of 5 M HCl in
water?
Ans = 730 g
Q21. A sample of NaOH weighing 038 g is dissolved in water and the solution is made to 50.0
mL in a volumetric flask. What is the molarity of the resulting flask. What is the molarity
of the resulting solution ?
Ans = 0.19 M
Q22. An aqueous solution of H2SO4 is found to contain 1.5 mole of H2SO4 in 1000 g of solvent,
what will be molarity of solution ? Given that density of solution is 1.147 g ml 1 Ans=1.5 M
Q23. A bottle of concentrated sulphuric acid (density 1.80 g cm-3) is labelled as 86% by weight.
What is the molarity of the solution ?
Ans = 15.8 M
Q24. Commercially available HBr solution contains 48% HBr by mass. What is the molarity of
this solution? The density of solution is 1.50 g cm-3.
Ans = 8.88 M
Q25. Calculate the molarity of 20% solution of KOH by mass whose density is 1.02 g ml -1.
Ans = 3.64 M
Q26. Calculate the resulting molarity of the solution that is obtained by adding 5 g of NaOH to
200 cm3 of
M
NaOH solution (density = 1.05 g cm-3). The density of resulting solution is
4
1.08 g cm-3.
Ans = 0.875 M
Q27. 6.90 M solution of KOH in water contains 30% by mass of KOH. Calculate the density of
KOH solution.
Ans = 1.288 g/ml
APPLICATION OF MOLARITY
Q28. 3.0 litre of water are added to 2.0 litre of 5 M HCl. What is the molarity of HCl in the
resultant solution?
Q29. 250 mL of 1.5 M solution of sulphuric acid is diluted by adding 5L of water. What is the
molarity of the diluted by adding 5L of water. What is the molarity of the diluted solution ?
Ans = 0.0714 M
SCO # 203 , SECOND FLOOR , SECTOR - 14 , PANCHKULA ; 4634812 (O) , 9888019721 , 9988819721 2
MUNISH KAKAR's INSTITUTE OF CHEMISTRY
Q30. Commercially available concentrated hydrochloric acid contains 38% HCl by mass.
(i) what is the molarity of the solution (density of solution = 1.19 g mL-1) ? Ans = 12.38 M
(ii) what volume of concentrated HCl is required to make 1.0 L of an 0.10 M HCl ?
Ans = 8.08 cm3
Q31. Commercially available sulphuric acid contains 93% acid mass and has a density of 1.84
g mL-1. Calculate
(i) the molarity of the solution
Ans = 17.5 M
(ii) volume of concentration acid required to prepare 2.5 L of 0.50 M H 2SO4 Ans = 71 mL
Q32. A bottle contains 500 ml of 2.4 M HCl solution. How much water should be added to
dilute it to 1.6 M HCl solution ?
Ans = 250 ml
Q33. 500 mL of aM solution and 250 mL of bM solution of the same solute are mixed and
diluted to 2 litre. The diluted solution shows the molarity 1.6 M. if a:b is 2:5, then
calculate a and b.
Ans a =2.84 , b = 7.11
Q34. What volume of 6 M HCl and 2 M HCl should be mixed to get one litre of 3 M HCl ?
0.25 L & 0.75 M
Q35. 100 ml of 10 M HCl are diluted with distilled water to a volume of 2 litre. Find out
molarity of the resultant solution.
Ans : 0.5 M
Q36. Calculate the volume of 80% H2SO4 by mass (density = 1.80 g cm-3) that is required to
obtain one litre of 20% H2SO4 by mass (density = 1.25 g cm-3).
Ans : 173.47 ml
Q37. What volume of deca molar aqueous solution of hydrochloric acid is required to prepare 2
dm3 of 5 M HCl solution?
Ans: 1 dm3
Q38. Calculate the volume of 80% H2SO4 by mass with density 1.80 g cm-3 which is required to
prepare 500 cm3 of 20% H2SO4 by mass with density 1.25 g cm-3.
Ans: 86.79 ml
Q39. A solution is prepared by mixing benzene and toluene in such a way that mole fraction of
toluene is 0.5. What is the mass percentage of solution w.r.t. benzene.
* Toluene = C7H8, Benzene = C6H6
Ans: 45.88% benzene
Q40. How many moles of NaOH required to prepare 5L of 2M aqueous solution of NaOH ?
Ans: 10 mole
SCO # 203 , SECOND FLOOR , SECTOR - 14 , PANCHKULA ; 4634812 (O) , 9888019721 , 9988819721 3
MUNISH KAKAR's INSTITUTE OF CHEMISTRY
SCO # 203 , SECOND FLOOR , SECTOR - 14 , PANCHKULA ; 4634812 (O) , 9888019721 , 9988819721 4