Sig Figs and Unit Conversions: Quick Guide and Practice Exercises

1. Find the number of sig figs in the following numbers 1)    2804 m 2)   2.84 km 3)   5.029 m 4)   0.003068 m 5)   4.6 x 105 m  Round the following numbers as indicated: To four figures: 1) 3.682417 2)21.860051 3)375.6523 4)0.000308582 5)578603 Do Now

2. Units of Measurement https://www.youtube.com/watch?v=_N9yUVtbtec

3. What is a Unit Conversion? • A unit conversion is a changing of one unit to another. • Unit Examples: • meters • grams • inches • feet • pounds • seconds • Any time you write down a number in Chemistry, you should have a unit written after it!!!

4. What is a Metric Unit? Metric units are the universally accepted units around the world (except for the US). They are the easiest to convert. Metric Unit Examples: meters liters Grams Base Units – all other metric units are based off of these (km, cm, ml, kg)

5. 1 2 3 MetersLitersGrams How do you use the “ladder” method? 1st – Determine your starting point. 2nd – Count the “jumps” to your ending point. 3rd – Move the decimal the same number of jumps in the same direction. Starting Point Ending Point __. __. __. 2 3 1 Ladder Method KILO1000Units HECTO100Units DEKA10Units DECI0.1Unit CENTI0.01Unit MILLI0.001Unit 4 km = _________ m How many jumps does it take? 4. = 4000 m

6. Compare using <, >, or =. 56 cm 6 m 7 g 698 mg Conversion Practice Try these conversions using the ladder method. 1000 mg = _______ g 1 L = _______ mL 160 cm = _______ mm 14 km = _______ m 109 g = _______ kg 250 m = _______ km

7. Metric Conversion Challenge Write the correct abbreviation for each metric unit. 1) Kilogram _____ 4) Milliliter _____ 7) Kilometer _____ 2) Meter _____ 5) Millimeter _____ 8) Centimeter _____ 3) Gram _____ 6) Liter _____ 9) Milligram _____ Try these conversions, using the ladder method. 10) 2000 mg = _______ g 15) 5 L = _______ mL 20) 16 cm = _______ mm 11) 104 km = _______ m 16) 198 g = _______ kg 21) 2500 m = _______ km 12) 480 cm = _____ m 17) 75 mL = _____ L 22) 65 g = _____ mg 13) 5.6 kg = _____ g 18) 50 cm = _____ m 23) 6.3 cm = _____ mm 14) 8 mm = _____ cm 19) 5.6 m = _____ cm 24) 120 mg = _____ g

8. Compare using <, >, or =. 25) 63 cm 6 m 27) 5 g 508 mg 29) 1,500 mL 1.5 L 26) 536 cm 53.6 dm 28) 43 mg 5 g 30) 3.6 m 36 cm

9. Dimensional Analysis A mathematical way to convert one unit to another. This works for metric units and non-metric (English) units. This works by taking the unit you are given and multiplying it by a conversion factor.

10. Metric Conversion Factors Knowing these conversion factors makes calculating conversions easy! These also work for liters and grams. Just replace the base unit (m) with a (g) or (l). 1 km= 1000 m 100 cm= 1 m 1000 mm = 1 m 10 mm = 1 cm

11. Example 1: Convert 3m to cm For meters to cancel out, meters in the conversion factor must be on the opposite side of the fraction (fence). 3m 100 cm 1m Multiply every number on top of the fence and divide by the bottom.

12. Example 2: Convert 1516 g to Kg 1516g 1 Kg 1000g

13. Try these yourself • Convert 1200 cm to m.

14. Try these yourself • Convert 5200mL to L.

15. Try these yourself • Convert 7200 mm to Km.