Question

1 . Calculate the composition of the following solution in weight/volume %. A. 20 g of NaCl in 1 L of solution 2. Calculate the composition of the following solution in weight/weight %. A.1 g KCl in 1.00 X 10 g solution 3. Calculate the molarity of each solution in Problem 1. 4. It is desired to prepare 0.5 L of a 0.1 M solution of NaCl from a 1 M stock solution How many milliliters of the stock solution must be taken for the dilution? 5. Calculate the osmotic pressure of a 0.5 M sucrose solution if the temperature is 298 K

Answer 1

1. Weight of NaCl = 20g ; Volume of solution = 1L = 1000mL

Thus, weight by volume % = (weight/volume)*100

= (20/1000)*100 = 2%

2. Weight of KCl = 1g in 10g of solution.

Thus, weight by weight% =

(weight of KCl/weight of solution)*100

= (1/10)*100 = 10%

3. Molarity of NaCl = (moles of NaCl)/V(of solution) in litres

Moles of NaCl =

(weight of NaCl in example)/(Molecular weight of NaCl)

Now, Molecular weight of NaCl = 23g/mil and in example weight = 20g

Thus, moles of NaCl = 20g/23g/mol = 0.8696mol

Thus, molarity = 0.8696 moles/1L = 0.8696 M

4.

solution To make a OIM sol- of Nad we need 0.1 moles of Nadt in IL water. So, for 0.5l solution we only need 0.05 moles of Nach We have IM solution, i.e. I mole Nace in IL water.. So for 0.05 moles we need = 0.05L of our = 50 mL of solution Thus we take 50 mL of solution which will give us 0.05 moles of Nad & we will add 450mL to of water it. 0.05 moles Thus melarity = (Total volume = 50 mL + 450mL) 2 500mL -0.5L 0.5 L