1. I survived the first week in Chem !!!!

2. Prefix mini- quiz

3. “How do I convert between these %%&! prefix systems ?”
There are many competing choices of prefixes for a given quantity in chemistry (and physics and biology) Nobody follows the rules……
“How do I convert between these %%&! prefix systems ?”
EXAMPLE
Common prefix units used to define wavelength, : m nm pm
mm (millimicron)
Å =10-1 nm

4. 15 m = ??? pm

5. Divide and conquer, maggot !
How to convert ???
Method 1) Algebraic (‘Marine’ way)
Doc’s story about his HS chem teacher
Divide and conquer, maggot !

6. 15 m = ___?____ pm Divide: 15 m = ___?____pm pm pm
The `Marine’ way of conversion:
15 m = ___?____ pm
Divide:
15 m = ___?____pm
pm pm
Conquer (substitute and calculate)
= ___?____
10-12
=15*10-6-(-12)
=15*10+6

7. Method 2) Factor-label (commonly taught by high school teachers)

8. 15 m = ___?____ pm 15 m * 10-6 m m 15 m * 10-6 m 1012 pm
`factor-label’ way of conversion:
15 m = ___?____ pm
1) Convert to base units (m)
15 m * 10-6 m m
2) Convert to base units to desired units & compute
15 m * 10-6 m m
1012 pm m
=15* pm
=15*10+6 pm

9. metric-Metric conversion problems done both ways
(on board)
How many cm in 5 dm
How many pg in 50 ng ?
5*101 =50 cm
50*103 pg=5*104 pg =50,000 pg

10. More Guided practice Unit conversions (via factor-label & Algebraic)
answers
4.57*104 g
Convert 45.7 kg to g
Convert 0.73 mL to L
730 L =7.3*102 L
Convert 7.2 kg/L to mg/ L
7.2 mg/L

11. Convert 5.0*103 ps to its equivalent in ms
U-DO-IT !!!
How many dg in 2.4 kg ?
2.4*104 dg
23 nm = ? m
2.3*10-2 m
Convert 5.0*103 ps to its equivalent in ms
5*10-6 ms
6 pg/L = ?? g/mL
6*10-3 g/mL

12. 5 ng= _____pg ?
500 pg
5000 pg
50 pg
0.5 pg