Question

The density of 3 M solution of NaCl is 1.25 g mL–1. Calculate the molalityof the solution.

Solution

Correct option is

2.79 m

 

3 M NaCl solution meants that 3 moles of NaCl are present in 1 L of the solution.

 Mass of 1 L, i.e., 1000mL of the solution

           = 

  = 

Mass of 3 moles of solute (NaCl)

                                     = 1074.5  g = 1.0745 kg

                                                    = 2.79 mol kg–1 = 2.79 m 

SIMILAR QUESTIONS

Q1

 

A man weight 175 1b. Express his weight in kg, Given that

1kg = 2.205 1b.

Q2

How many inches are there in 3.00 km? Given that 1 km = 1000 m, m = 1.094 yd, 1 yd = 36 in.

Q3

What is the mass (in grams) of an aluminum block whose dimensions are.and whose density is 2.7 g/cm3? Given that 1 in. = 2.54 cm. 

Q4

The mass of precious stones is expressed in terms of ‘carat’. Given that 1 caret = 3.168 grains and 1 grams = 15.4 grains, calculate the total mass of a ring in grams and kilograms which contains 0.500 carat diamond and 7.00 grams gold.

Q5

4.90 g of KClO3 when heated produced 1.92 g of oxygen and the residue (KCl) left behind weight 2.96 g. Show that these results illustrate the law of conservation of mass.

Q6

Chlorine has two isotopes of atomic mass units 34.97 and 36.97. The relative abundances of these two isotopes are 0.755 and 0.245 respectively. Find the average atomic mass of chlorine.

Q7

Calculate the molecular mass of glucose (C6H12O6)molecule.

Q8

A solution is prepared by adding 2 g of a substance A to 18 g of water. Calculate the mass percent of the solute.

Q9

How many grams of NaOH should be dissolved to make 100 cm–3 of 0.15 M NaOH solution? 

Q10

Calculate the number of oxalic acid molecules in 100mL of 0.02 N oxalic acid solution