1. Prove it! 33.5 kg = __________ dg 2.45 mL = _________ cL 50.5 dm 3 = _________ mL

2. Prove it! 33.5 kg = __335,000____ dg 2.45 mL = _0.245____ cL 50.5 dm 3 = __50,500___ mL

3. Prove it! 1.An object has a mass of 25 grams and a volume of 13.5 cm 3. What is the density? 2.An object has a density of 3.55 g/mL. Its mass is 20.0 g, what is its volume?

4. 1.1.85g/cm 3 2. 5.63 mL

6. Sig Fig Story A group of Civil Engineers were at a conference being held in Central Australia. As part of the conference entertainment, they were taken on a tour of the famous rock, Uluru. "This rock", announced the guide, "is 50 000 004 years old." The engineers - always impressed by precision and accuracy in measurement - were astounded. "How do you know the age of the rock so precisely?" asked one of the group. "Easy!", came the reply. "When I first came here, they told me it was 50 million years old. I've been working here for four years now."

7. Accuracy vs. Precision

10. Place 3 rulers here!

11. How many sig figs are in a number? The Atlantic – Pacific Rule  If the decimal is present, start counting sig figs from the left, “Pacific”, side with first non-zero digit.  If the decimal point is absent, start counting sig figs from the right, “Atlantic”, side with first non-zero digit.  Once you start counting, don’t stop! PacificAtlantic “P” is for PRESENT decimal “A” is for ABSENT decimal

12. Significant Figures Rules 1.Digits 1 – 9 are always significant. 2.Trailing zeros after a decimal are always significant. 2.0 cm (2 sig figs) 3.Zeros between significant digits (1 – 9) are always significant. 20.1 cm (3 sig figs) 4.Zeros used a placeholders for decimals are NOT SIGNIFICANT. 0.02 cm (1 sig figs) 5.Zeros trailing significant digits without decimals are NOT SIGNIFICANT. These are also placeholders.20 cm (1 sig fig) 6.Exponents and conversion factors are NOT significant figures. 2.0 x 10 19 (2 sig figs)

13. Significant Figures Addition and Subtraction –Round the FINAL answer to the LEAST number of decimal places Actual answer to correct number of sig figs : 255.5 mL 255.507 mL

14. Significant Figures Multiplication and Division –Round the FINAL answer to the TOTAL NUMBER of LEAST number of significant figures Actual answer to correct number of sig figs : 190,000 cm 3 188,784 cm 3 1.9 x 10 5