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# Chem01

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9/12/2009

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### Chem01

1. 1. A B 1 2.7 4 2 2.8 4 3 3.1 4 4 2.9 4 5 3.3 4 6 2.8 4
2. 2.  Why do we use significant digits? • Because any measurement involves errors
3. 3.  What is the difference between 26kg and 26.0kg? Accuracy!  Finding significant digits  Rule 1: • Look for a decimal point. • e.g. 26kg. NO decimal point • e.g. 26.0kg.YES decimal point • e.g. 26.0000kg.YES
4. 4.  Rule 1: Look for decimal point  Rule2: if there is no decimal point, the zeros at the end do not count. • 26kg • 260kg • 2600000000kg • (all have 2 significant digits)
5. 5.  Rule 1: Look for decimal point  Rule2: if there is no decimal point, the zeros at the end do not count.  Rule3: if there is a decimal point, the zeros at the beginning do not count. • 0.003kg (1 significant digit) • 0.0030kg (2 significant digits) • 0.0030000kg (5 significant digits) • 1.0030kg (5 significant digits)
6. 6.  .0026701 kg  2.6701 kg  2.67010 kg  2.670100 kg  10.0550 kg  3500 m  1,809,000 L
7. 7.  3.052 m X 2.10 m X 0.75 m =  4.8069 m3  Which number has the least number of significant digits?  The answer has the same # of significant digits as the number with the smallest #.  4, 3, 2. Answer = 4.8069 m3 .  4.8 m3
8. 8.  100 =1  101 =10  102 =100  10-1 =0.1  10-2 =0.01  17 = 1.7 x 101
9. 9.  32,700 • 3.27 x 104  1,024,000 • 1.024 x 106  .0047100 • 4.71 x 10-3
10. 10.  A. Find the number of significant digits in: • a) 400 b) 4000 c) 400.1 d) 400.10 • e) 0.001 f) 0.0010  B. Scientifically notate: • a) 0.0358 • b) 358,000