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Key Things: Laboratory Introduction

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- Be able to correctly identify, spell and understand the use of all lab equipment
- Recognize the safety symbols
- Read over working with chemicals – you will need to know how to work with chemicals for your labs
- Know your lab safety rules
- Know the steps to follow in case of injury
- What are your first aid procedures?

- Scientific Notation
- Expresses numbers as a multiple of two factors: a number between 1 and 9 X 10 raised to a power (exponent)
- When moving a decimal to the left it is a positive exponent.
- When moving a decimal to the right it is a negative exponent.

- Expresses numbers as a multiple of two factors: a number between 1 and 9 X 10 raised to a power (exponent)

- Adding and Subtracting
- Be sure that the exponents are the same
- Then add or subtract the decimal number as listed

- Be sure that the exponents are the same
- Multiplication and Division
- To multiply – multiply the first factors then add the exponents
- To divide – divide the first factors then subtract the exponent of the divisor from the exponent of the dividend

- Write the following numbers in scientific notation
0.0045834 mm 438,904 s

- Complete the following addition and subtraction problems
6.23 x 106 kL + 5.34 x 107 kL

9.87 x 104 g – 6.2 x 103 g

- Complete the following multiplication and division problems
(4.8 x 105 km) * (2.0 x 103 km)

(8.4 x 106 L) ÷ (2.0 x 103 L)

- Fractions to decimals
1/5 = 0.2

1/4 = 0.25

1/3 = 0.33

1/2 = 0.5

2/3 = 0.67

3/4 = 0.75

4/5 = 0.8

- Seven basic SI units
- Base units are based on a physical object or process
- length (m - meter), mass (kg - kilogram), time (s - second), electric current (A -ampere), temperature (K - Kelvin), amount (mol - mole), luminous intensity (cd - candela)

- Derived units are created by multiplying or dividing the 7 basic units
- 1 L = 1 dm3
- 1 mL = 1 cm3
- J = kgm2/s2

- Distinguish between accuracy and precision in measurement
- Accuracy – extent to which a measurement approaches the true value of a quantity
- Agreement of a measurement with the accepted value of the quantity

- Precision – degree of exactness or refinement of a measurement
- How well several determinations of the same quantity agree

- Accuracy – extent to which a measurement approaches the true value of a quantity

- Calculating percent error
% error = theoretical – actual x 100

theoretical

The accepted length of a steel pipe is 5-m. Calculate the percent error for each of these measurements

- 5.25 m
- 4.75 m
- 5.5 m

- Rules recognizing significant figures
- Non-zero numbers are always significant
- Zeros between non-zero numbers are always significant
- All final zeros to the right of the decimal place are significant
- Zeros that act as placeholders are not significant. Convert quantities to scientific notation to remove placeholder zeros
- Counting numbers and defined constants have an infinite number of significant figures

- Rounding Rules
- If the digit to the immediate right of the last significant figure is less than five, do not change the last significant figure
- If the digit to the immediate right of the last significant figure is greater than five, round up the last significant figure

- How many significant figures in the following measurements?
- 431,801 kg
- 10,235.0 mg
- 0.004384010 cm
- 0.00986451cg

- Write the above in scientific notation to four significant figures

- Rules for using significant figures in calculations
- Addition or Subtraction
- The answer can have no more digits to the right of the decimal point than there are in the measurement with the smallest number of digits to the right of the decimal point
- 10.03542 m
+12.02 m

22.05542 m = 22.06 m = 2.206 X 101 m

- Addition or Subtraction

- Rules for using significant figures in calculations
- Multiplication or Division
- The answer can have no more significant figures than there are in the measurement with the smallest number of significant digits
- 1.1135 g/mL * 500. mL = 556.75g = 5.5675 x 102g = 5.57 x 102g

- The answer can have no more significant figures than there are in the measurement with the smallest number of significant digits

- Multiplication or Division

- Round the answers to each of the following problems to the correct significant figures
- 7.31 x 104 + 3.23 x 103
- 8.54 x 10-3 – 3.41 x 10-4
- (2.4 x 102) * (3.26 x 104)
- (1.024 x 102) ÷ (5.12 x 101)

- Use metric prefixes to convert metric units
- 1G= 109 base units
- 1 M = 106 base units
- 1 k= 103 base units
- 1 d = 10-1 base units
- 1c= 10-2 base units
- 1 m = 10-3 base units
- 1ų = 10-6base units
- 1 n = 10-9 base units
- 1 p = 10-12 base units

- Convert the following measurements
- 5.7 g to milligrams
- 45.3 mm to meters
- 10 km to centimeters
- 783 kg to milligrams
- 98 mL to deciliters

- 6 km = ______m
- 4.9 mg = _____g
- 7.6 dm = ___mm
- 32.1 g = ______ cg
- 5.6 X10 3 cm = ___m
- 760 g = ____ kg
- 4.50 m = _____ ų m
- 1.23 mL = ___ L
- 12 km = _______nm
- 6.4 mg = ____pg

- 6 km = 6X103 m
- 4.9 mg = 4.9X10-3g
- 7.6 dm = 7.6X102 mm
- 32.1 g = 3.21X103 cg
- 5.6 X10 3 cm = 5.6X101m
- 760 g = 7.6 X10-1 kg
- 4.50 m = 4.50X106ų m
- 1.23 mL = 1.23X10-3 L
- 12 km = 1.2 X1013nm
- 6.4 mg = 6.4X109pg

- Accuracy
- Precision
- Scientific method: Experiment, Hypothesis, Observation, Conclusion
- Qualitative data
- Quantitative data

- Significant figure rules and exponent rules
- base unit- define and base units
- scientific notation and rounding
- conversion factor
- dimensional analysis-know all metric conversions

- 254.3 g = ______kg
- 2.75 kg = ______g
- 534.1 g = ______cg
- 1.75 dm = ______m
- 8.7 mm = _______m
- 45.6 ML = ______L
- 672 cg = _______g

- 254.3 g = 2.543 X 10 -1 kg
- 2.75 kg = 2.75 X 10 3 g
- 534.1 g = 5.34 X 10 4 cg
- 1.75 dm = 1.75 X 10-1 m
- 8.7 mm = 8.7 X 10 -3 m
- 45.6 ML = 4.56 X 10 7 L
- 672 cg = 6.72 g

- Know and understand your vocabulary words
- Be able to identify the difference between qualitative and quantitative data
- Be able to identify the difference between accuracy and precision
- Be able to convert using dimensional analysis
- Know the steps of the scientific method
- Be able to describe the differences between a hypothesis, theory, and a law