Question

a solution containing for 4 10.3 gram of H2 s o4 per litre of the solution at 20 degree Celsius if density is 1.243 gram per centimetre cube What will be the molality and molarity​

Answer 1

Molarity is the ratio of the moles of solute to the total liters of solution. The solution includes both solute and solvent. Molarity is also known as molar concentration of a solution. The unit of molarity is M or mol/L. A 1M solution is said to be “one molar”.

So, molarity equation is given by:

M=Molesofsolute  /  Volume of solution in litres

Molality is the ratio of the moles of solute to the kilogram of a solvent.

m=Moles solute / kg solvent

For molarity:

Molecular mass of H2SO4=98

Number of moles of H2SO4= 410.3 /98 = 4.186

MolarityofH2SO4solution=No.of molesof H2SO4 / Volume of solution in lit

                                                            = 4.186/ 1

                                                            = 4.186M

For Molality:

Mass of 1 liter H2SO4solution = 1000 × 1.243 = 1234g

Mass of water= (1243 - 410.3) = 832.7g

                                                     = 832.7 / 1000kg

Molality of solution=No.ofmoles of H2SO4 /  Mass of water in kg

                                           = 4.186832.7×1000

                                             = 5.027m

Hence the molarity will be 4.186 M and molality will be 5.027m

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