Question

A. Calculate the concentrations of K1 and NO3 2 in an aqueous solution prepared by dissolving 30.3 g KNO3 in enough water to make 300. mL of solution.

B. Calculate the concentrations of Al13 and SO4 22 in an aqueous solution prepared by dissolving 17.1 g Al2 (SO4 ) 3 in enough water to make 400. mL of solution.

C. Calculate the concentrations of Na1 and SO4 22 in an aqueous solution prepared by dissolving 852 g Na2 SO4 in enough water to make 4.00 L of solution.

D. What mass (in g) of CaCl2 is needed to prepare 100. mL of an aqueous solution that is 0.25 M in Cl2?

E. If 100. mL of 18.0 M H2 SO4 solution are diluted to 10.0 L, what are the concentrations of H1 and SO4 22 in the diluted solution?

Answer 1

A. molarity= weight of sustance *1000/gram molar mass *volume in ml
         = 30.3*1000/101*300 = 1 M
KNO3 ----> K⁺ + NO3-
1 m       1M    1M
concentration of K+ is 1m
concentration of No3- is 1M

B. MOLARITY= weight of sustance *1000/gram molar mass *volume in ml
           = 17.1*1000/342*400
           = 17100/136800 = 0.125M
Al2(SO4)3 ----> 2Al+3 + 3So42-
0.125M          2*0.125 3*0.125
concentration of Al+3 is 0.25M
concentration of SO42- is 0.375M

C.MOLARITY= weight of sustance /gram molar mass *volume in L
          = 852/142*4 =1.5M
Na2SO4 ---> 2Na+ + So42-
1.5M        2*1.5M 1.5M
concentration of Na+ is 3M
concentration of so42- is 1.5M

D. MOLARITY= weight of sustance *1000/gram molar mass *volume in ml
weight of sustance = molarity *gram molar mass *volume in ml/1000
                   = 0.25*111*100/1000
                   = 2.775gm of Cacl2

E.M1V1 = m2V2
18*100 = M2*10000
     M2 = 1800/10000
     M2 = 0.18M
H2SO4 -----> 2H+ + SO42-
0.18M        0.36M 0.18M
concentration of H+ is 0.36M
concentration of So42- is 0.18M