1. CHEM 1011
Laboratory Techniques: Using the Laboratory Gas Burner; Making Laboratory Measurements

2. Safety
Put on Goggles
And Apron

3. Objectives Learn to use Bunsen burner
Learn to use laboratory equipment
Learn to take Measurements
Record Measurements using the proper number of significant figures

4. CH4 (g) +2O2 (g) → CO2 (g) + 2H2O (g)
Bunsen Burner
Allows Controlled Mixture of Gas and Air
Hottest Flame
Nonluminous
Violet outer cone
Complete combustion occurs
CH4 (g) +2O2 (g) → CO2 (g) + 2H2O (g)

5. Bunsen Burner Cooler Flame Less Air Luminous Yellow Flame
No Inner Cone
Smokey due to incomplete combustion

6. Glassware Glassware in lab is a borosilicate glass
Consists of silica and borax
Does not soften much under 800˚C
Pyrex or Kimax
Low thermal Expansion coefficient
Unlike soft Glass (SiO2)
softens from ˚C
High thermal Expansion coefficient

7. Laboratory Measurements
Metric system uses base 10 for measurements and conversions
Conversions are done by multiplying or dividing by 10 7

8. Laboratory Measurements
Evaluate physical and chemical environment
length, volume, mass, energy, and temperature
Good laboratory techniques are invaluable 8

9. Accuracy Closest to the true value True value = 34.878 Device measures
34.881
34.876
34.877 9

10. Precision Reproducibility of the measurement Little variability
True value =
Device measures
35.001
35.002
35.000

11. Precision and Accuracy

12. Significant Figures When measuring:
(1) uncertainty in last digit recorded
25.45
(2) the # of significant figures contains all known #’s + one estimated
known = 25.4; estimated = 0.05

13. Examples 13

14. Division
The Answer’s # of sig. fig. are same as number with the fewest digits being divided
12.3 ÷ =
= 1.97

15. Multiplication
The Answer’s # of sig. fig. are same as number with the fewest digits being multiplied
0.72 × =
= 0.82

16. Addition
The Answer’s # of sig. fig. are same as number with the fewest digits behind decimal being added =
= 15.37

17. Subtraction
The Answer’s # of sig. fig. are same as number with the fewest digits behind decimal being subtracted
– 3.63 =
= 3.21

18. Calculations
Length: Record measurement to the nearest 16th of an inch

19. Conversion Table

20. Calculations (Measurement)
Record measurements
Conversions can be made by dividing or multiplying by powers of 10
Ex. 34 cm × 10 mm/1 cm = 340 mm
Area L × W (340 mm × 23 mm) = 8160 mm2

21. Calculations (Volume)
Record Volume
Convert using the conversion chart
e.g., 48 mL × 1 L/1000 mL = L
Calculate percent error =
(theoretical value – actual value)/ theoretical value × 100

22. Calculations (Mass) Record values Convert from g to mg
e.g., 15 g × 1000mg/1g = mg

23. Calculations (Temperature)
Record the Value in degrees Celsius
Convert to Degrees Fahrenheit and Kelvin
Degrees Fahrenheit use (9/5 (C) + 32
Degrees Kelvin use (C + 273)