question_answer 1)

Calculate the molarity of each of the following solutions : (a) 30 g of Co(NO3)2.6H2O in 4.3 L of solution (b) 30 mL of 0.5 MH2SO4 diluted to 500 mL  

Answer:

(a) Molar mass of Co(NO3)2.6H2O = 58.7 + 2(14 + 48) + 6 x 18 g mol-1 = 310.7 g mol-1 No. of moles of Co(NO3)2.6H2O   Volume of solution = 4.3 L Molarity of solution   (b) Apply molarity equation M1V1 = M2V2 Before dilution After dilution 0.5× 30 = M2 × 500    Molarity after dilution = 0.03 M   = 154 g mol?1  No. of moles of benzene (nC6H6) No. of moles of CCl4 (nCCl4) Mole fraction of benzene Mole fraction of CCl4 = 1 ? 0.458 = 0.542