Question

You need to prepare 250.0 mL of a 1.35 M HCl solution from a 2.00 M HCl stock solution.

a. Which glassware should you use to make the solution?

A. beaker

B. Erlenmeyer flask

C. volumetric flask

b. How should the correct amount of stock be obtained?

A. Measure out x g on a balance

B. Measure out x mL using a volumetric pipet

C. Measure out x mL using a graduated cylinder

c. Based on your answer above, what is the value of x?

d. How should the solution be mixed together?

A. Fill the container to the 250 mL mark then add the correct amount of stock solution.

B. Add the correct amount of stock solution then fill to the 250 mL mark with water.

C. Fill the container partially with water, add the correct amount of stock solution, then fill to the 250 mL mark with water.

D. None of these is the correct way to mix the stock solution.

Answer 1

Answer:

a. C. volumetric flask

b. B. Measure out x mL using a volumetric pipet

c. 168.75mL

d. B. Add the correct amount of stock solution then fill to the 250 mL mark with water.

Explanation:

• The volumetric flask is mainly used in analytical chemistry to contain standard solutions or to prepare dilutions of a certain concentration of a reagent.
• The volumetric pipette is used to deliver a given volume with greater precision and accuracy.
• To make a dilution, the formula C1*V1 = C2*V2 is used where C is the concentration of the solution, in this case of molarity. V is the volume of the solution in ml and terms 1 and 2 correspond to the concentrated and diluted solutions respectively.

$V2=\frac{1.35M*250mL}{2.00M} =168.75mL$