Exercises series I
Exercise 1
One litre of an aqueous solution contains:
5.85 g NaCl, 3.28 g PO4Na 3,9 g glucose, 0.6 g urea. It is supposed that NaCl and PO4Na3 are completely dissociated.
Calculate the molarity, osmolarity, ionic, and equivalent concentration of the solution.
The molar masses of NaCl=58.5, PO4Na3=164, glucose=180, and urea=60 g/mol.
Exercise 02
One liter of an aqueous solution contains 60 g of sucrose, 1.8 g of urea, 17.6 g of NaCl, and 2.98 g of Na2SO4. 100 ml of this solution is taken and 1 L of pure water is added.
1. Calculate the osmolarity, ionic, and equivalent concentration.
2. Determine the total ionization coefficient (i) of the solution.
The molar masses of Na2SO4=142, sucrose=342, urea=60 g/mol.
1. Calculate the molar concentration,
The number of moles of each solute in 100 ml
The molar concentration of solutes after adding 900 ml of water
The total volume of the daughter solution is equal to 100+900=1000 ml= 1l
2. osmolarity concentration of solution
3. The ionic concentration of the solution
4. The equivalent concentration of the solution
Exercise 03
To measure the resistance of an electrolytic solution, a voltage of U=1 V is applied between the two electrodes of the conductometric cell, and a current intensity of 12 mA is measured. The immersed surface of the cell electrodes is S=1 cm² and the distance between these two electrodes is L=1 cm.
Calculate the resistance (R) of the solution between the two electrodes
conductance (G) of the solution between the two electrodes
conductivity (σ) of the solution between the two electrodes
Calculate the resistance R : 83.33 Ω
Calculate conductance (G) : 0.012 S
Calculate the conductivity (σ) :120 S/cm
Exercise 04
Mix 200 ml of a 5 mol/l sodium chloride solution (KCL) with 800 ml of a 1.25 mol/l sodium chloride NaCl solution.
Calculate the conductivity σ_1 and σ_(2 )of each solution.
Calculate the conductivity σ of the mixture.
The ionic molar conductivities λ (Na⁺) =5.01×10-3, λ (Cl⁻) =7.63×10-3 and λ (K⁺) =7.35×10-3 S.m²/mol.
1. Calculate of conductivity σ1:
2. Calculate of conductivity σ2:
3. Calculate of conductivity σ of the mixture
