ANSWERS to Review Questions for Calibration of Volumetric Apparatus and Preparation of Solutions
1. How would you prepare a 0.2 N HCL, 0.5 N HCL from 1 NHCL, to a final volume of 30 mL, 50 mL, and 60 mL?
Use the formula C1V1= C2V2
Where C1= 1N HCL
C2= 0.2 N HCL, 0.5 NHCL
V1 = Unknown
V2 = 30 mL, 50 mL, and 60 mL
Substitute properly and solve.
C1V1 = C2V2,
(1N)(V1) = (0.2 N HCL)(30 mL)
V1 = 0.2 X 30 divided by 1
V1 = 6 mL of 1 N HCL added to 24 mL of distilled water.
2. Give examples of primary standards for acid and base solutions.
refer to Bishop
3. List the requirements of a good primary standard.
It should not be hydroscopic.
It should be 99.9 % pure.
It should have a high molecular weight.
4. What is the most frequently used cleaning solution for glassware?
Potassium dichromate in sulfuric acid.
5. Name two general types of pipets and their corresponding calibrating medium.
To deliver (TD) = calibrating medium is water
To contain (TC) = calibrating medium is mercury
6. How do you read opaque and clear solutions?
Opaque solutions - read at upper meniscus
Clear solutions - read at lower meniscus
7. How do you prepare 0.85 % NaCl solution?
% = W/V X 100
W = (%)(V) over 100
W = (0.85)(100) over 100 (assume the total volume of the solution is one if the volume is not given)