Significant Figure RULES

Unit 1 Review

Significant Figure RULES

·  Significant figures include all of the digits that are known, plus a last digit that is estimated

·  Measurements must always be reported to the correct number of significant figures because calculated answers often depend on the number of significant figures in the values used in the calculations.

Rules for determining whether a digit in a measured value is significant

1.  Nonzero digits are significant. 5.23 has 3 significant figures

2.  Zeros between nonzero digits are significant. 5001 has 4 significant figures

3.  Zeros in front of nonzero digits are not significant, they are only place holders. 0.000099 has 2 significant figures

4.  Zeros at the end of a number and to the right of a decimal place are significant. 1.0100 has 5 significant figures

5.  Zeros to the left of an understood decimal point are not significant, they are only place holders. 55000 has 2 significant figures

6.  Defined quantities and counted quantities have unlimited number of significant figures. They do NOT affect the rounding of an answer. [defined quantity example 1 foot = 12 inches, counted quantity example 31 students]

Section 1: Significant Figures

List the number of significant figures for the following numbers.

a.  2.03

b.  1.0

c.  2.00

d.  0.00860

e.  1.0030

f.  967,000

g.  5.10

h.  0.0000065

i.  0.009

Perform the following calculations and write the answer that your calculator gives you. Then round to the correct number of significant figures

Problem / Calculated Answer / Answer Rounded to the correct
number of significant figures
1 / 2.698 x 33.20 x 1.5611
2 / 8.032 / 0.591
3 / 3.2 x 4.21
4 / 2.5000 x 3.92
5 / 3 x 154
6 / 3.00 x 154

Section 2: Scientific Notation

Convert the following into scientific notation.

Number / Scientific Notation
Ex: 0.0000053m / 5.3x10-6m
1.8800000000m
2. 0.00000000006kg/m3
3. 8002000Hz

Convert the following into the appropriate number.

Scientific Notation / Number
Ex: 9.89x103nm / 9890nm
6. 4.0x10-5m3
7. 4.0229x108nm
8. 3.15x103mg

Solve the following.

11) 6.0x108g/3.0x105cm3=______

12) 1.35x109g+3.62x109g=______

13) (6.3x1016cm)(5.2x10-7cm2)=______

Section 3: Metric Conversions

1)  Convert 3.7 mL to KL.

2)  Convert 400 mm to m

3)  Convert 42 Mm to µm.

4)  Convert 20 mph to m/s. (1 mile = 1.609 km)

5)  The doctor tells you that you need to take 15mL of medicine a day until you are healthy. You buy a gallon of medicine from the pharmacy. How many days would this medicine last you? (1 gallon = 3.785 Liters)

Section 4: Density

1.  A piece of wood that measures 3.0 cm by 6.0 cm by 4.0 cm has amassof 80.0 grams.What is thedensityof the wood?Would the piece of wood float in water?

2.  A cup of gold colored metal beads was measured to have a mass425 grams.By water displacement, thevolumeof the beads was calculated to be 48.0 cm3.Given the following densities, identify the metal.

Gold: 19.3 g/mL

Copper:8.86 g/mL
Bronze:9.87 g/mL

3.  An ice cubemeasuring 5.80 cm by 5.80 cm by 5.80 cm has adensityof 0.917 g/mL.What is the mass?