# Chapter 3: Scientific Measurement - PowerPoint PPT Presentation

PPT – Chapter 3: Scientific Measurement PowerPoint presentation | free to download - id: 10fe29-NWY4N

The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
Title:

## Chapter 3: Scientific Measurement

Description:

### Qualitative observations using the 5 senses ... Measure using a graduated cylinder at the meniscus (the bottom of the curve) Units: mL or L ... – PowerPoint PPT presentation

Number of Views:71
Avg rating:3.0/5.0
Slides: 22
Provided by: Jar104
Category:
Tags:
Transcript and Presenter's Notes

Title: Chapter 3: Scientific Measurement

1
Chapter 3 Scientific Measurement
• A. Types of Measurements
• Quantitative number and unit
• counting or measuring
• Qualitative observations using the 5 senses
• - distinctive characteristics
determine the specific make-up of a substance
• In chemistry, we use both quantitative and
qualitative types of analysis

2
• B. Scientific Notation
• Used to shorten really long numbers
• General form _ . _ x 10exp
• Positive exponent gt 1 (greater than)
• Negative exponent lt 1 (less than)
the first set of numbers is the number negative
(a neg. exp. does not mean a neg. !)
• ex. 3.6 x 103 is a pos. gt 1
• 3.6 x 10-3 is a pos. lt 1 (but gt 0)
• -3.6 x 103 is a neg.

3
• Why use scientific notation?
• ex. 3.6 x 103 3600. (decimal moves right)
• 3.6 x 10-3 .0036 (decimal moves left)
• -3.6 x 103 -3600
• 6.02 x 1023 whoa mama!
• 602000000000000000000000 (21 0s)
• Practice these
• ex. 3.17 x 107
• 6.1 x 10-5
• 1800000
• 0.000482

31700000 0.000061 1.8 x 106 4.82 x 10-4
4
• How do you plug scientific notation into the
calculator for calculations?
• Hit open parenthesis button (
• Type in the decimal part _ . _
• Hit the exponent button EXP or EE (this
button means x 10) - no need to type x 10
• Type in the exponent part
• Hit the close parenthesis button )
• Hit the operations button (, -, x, )

5
• Enter 3.62171 x 10-14 into the calculator
• 3.62171E-14 3.6 x 10-14
• 3.62171 x10-14 3.6 x 10-14
• 3.62171 -14 3.6 x 10-14
• Practice these
• ex. (3.0 x 104) x (2.0 x 102)
• (8.0 x 109) (2.0 x 104)
• (3.6 x 1013) / (1.4 x 10-3)
• (7.481 x 10-5) x (4.2 x 10-2)

6.0 x 106 4.0 x 105 2.6 x 1016 3.1 x 10-6
6
• C. Significant Figures
• Significant figures (sig figs) are the
important numbers in a
• Answers should be reported according to the least
amount of decimal places in the data
• ex. (7.481 x 10-5) x (4.2 x 10-2) 3.1 x 10-6
• 3 decimals 1 decimal 1 decimal

7
• Rounding to a decimal place
• When you have more numbers in your calculator as
an answer and you have to round to the correct
number of sig figs
• Look at the decimal place to the right of the
last sig fig that you need to report
• If the number is 5-9, you round up
• If the number is 0-4, you round down (last number
stays the same)

ex. 726.835 to 2 decimals 24.8514 to 3
decimals
726.84 24.851
8
• Rules to determine sig figs from numbers
• Every non-zero digit in a measurement is
significant (ex. 24.7, 0.743, 714)
• Zeros between non-zeros are significant (ex.
7003, 40.79, 1.503)
• Zeros to the left of non-zeros are not
significant (ex. 0.0071, 0.42, 0.000099)

9
• Rules (cont.)
• Zeros at the end of a number (right of the
decimal) are significant (ex. 43.00, 1.010)
• Zeros at the end of a number (left of the
understood not written decimal) are not
significant (ex. 300, 7000, 27210)
• Zeros at the end of a number (left of the
decimal) are significant (ex. 300., 27210.)

10
• Sig figs in measurements
• Write down all known numbers, plus one extra
number that is estimated
• ex.

(a) 0.6 m 60 cm 600 mm
(b) 0.61 m 61 cm 610 mm
(c) 0.607 m 60.7 cm 607 mm
11
• Precision vs. accuracy
• Precision how close measurements are to
each other (repeated trials)
• Accuracy how close measurements are to
the actual or accepted value
• ex.

Precise but not accurate
Both precise and accurate
Not accurate and not precise
12
• Percent error
• Experimental (e) your value obtained
• Accepted (a) the correct or true value
• absolute value (make value positive)
• Formula accepted experimental x 100
• accepted
• Shorthand a e x 100
• a
• (use correct of sig figs)

13
• D. Types Of Measurements
• SI units
• SI - International System of Units (standard
measurements in science)
• Uses the metric system (based on 10)
• Time seconds (s)
• Temperature Kelvin (K)
• Length meter (m)
• Mass kilogram (kg)
• Volume cubic meter (m3)

14
• Prefixes used
• Prefixes go in front of the unit symbol and are
always lower case
• Kilo (k) 1000 or 103 (1000 times larger)
• Deci (d) 0.1 or 10-1 (10 times smaller)
• Centi (c) 0.01 or 10-2 (100 times smaller)
• Milli (m) 0.001 or 10-3 (1000 times smaller)

15
• Length
• Units
• Meter (m) SI unit
• Centimeter (cm)
• Millimeter (mm)
• Use a meter stick or ruler (cm side only)
• Conversions
• 1 m 100 cm 1000 mm
• 1 cm 10 mm

16
• Mass
• Weight the force on an object by gravity
• is different on the earth and moon
• Mass the amount of matter (stuff) in an
object
• is the same with or without gravity
(the same on the earth and moon)
• Use a digital balance in lab

17
• Mass (cont.)
• Units
• Kilogram (kg) SI unit
• Gram (g)
• Milligram (mg)
• Conversions
• 1 kg 1000 g
• 1 g 1000 mg

18
• Volume
• Regular shaped solid
• Measure using a meter stick or a cm ruler
• V L x W x H
• Units cm x cm x cm cm3
• Irregular shaped solid
• Measure using the displacement method (use
• Units mL or L

19
• Volume (cont.)
• Liquid
• Measure using a graduated cylinder at the
meniscus (the bottom of the curve)
• Units mL or L
• Units
• Liter (L)
• Milliliter (mL)
• Cubic centimeter (cm3) or (cc)
• Conversions
• 1 L 1000 mL
• 1 mL 1 cm3 1 cc

20
• Density
• Density mass / volume
• D m / V
• Mass is in grams
• Volume is either in cm3 or mL
• Density of water (pure H2O) 1.0 g/mL
• 1 g H2O 1 mL H2O
• Object floats in H2O if D lt 1.0 g/mL
• Object sinks in H2O if D gt 1.0 g/mL

21
• Temperature
• Scales
• Fahrenheit (?F)
• Celsius (?C)
• Kelvin (K) SI unit
• Only Celsius (used most of the time, especially
in lab) and Kelvin are used!
• Use a thermometer in lab