Chapter 23 - Lab Techniques

Question 1

Define accuracy vs. precision

Answer 1

• Accuracy: A measurement giving the actual value of the sample with limited deviation
• Precision: Repeatability of a set of measurements of the same sample

Question 2

What are benefits/disadvantages of glass vs. plastic laboratory materials?

Answer 2

Plastic:

• Advantage: Light weight, difficult to break
• Disadvantage: Not heat resistant, solvent compatibility

Glass:

• Advantage: Strong, inert, transparent, heat resistant
• Disadvantage: Chemicals may interact with glass surface

Question 3

What is non-calibrated glassware vs. calibrated glassware?

- Examples

Answer 3

Non-calibrated: Simply used for containing, mixing, reacting, etc.
- Ex. Test tube, beaker, etc.

Calibrated: Used for accurate and precise measurements
- Ex. Graduated cylinder, buret, etc.

Question 4

What is a pH meter?

• Range
• Acidic vs. basic vs. neutral range

Answer 4

Measurement equipment that detects pH
- Ranges from 0-14
- 0-6 is acidic
- 7 is basic
8-14 is basic

Question 5

What are 2 different weight determination techniques?

Answer 5

1. Standard Lab Balance: Milligran weights needing more accuracy (+/- 0.5mg)
2. Analytical Balance: More sensitive applications that have glass sliding doors to protect against drafts (+/- 0.01mg)