Transcript Notes Unit 1-5

WARM UP
8-25-15
1.
Matter
Compound
Provide 2
examples
Provide 2
examples
Provide 2
examples
Homogeneous
Provide 2
examples
Heterogeneous
Provide 2
examples
Agenda
Homework
Notes Unit 1-5
Lab Density
Aug 26 - Notebook check Unit 1
Aug 29 - Online HW Unit 1
Aug 30 - Test Unit 1
Unit 1-5
Density and Rounding
Measurements
Properties of Matter

Chemical Properties: A property of matter
that let it react with another chemical

Chemical properties can only be identified by
trying to cause a chemical change
Properties of Matter

Physical Property: A property that can be
determined without changing the nature
of the substance

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Example: sugar’s physical properties would include
that it is solid, white
More examples:

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State of matter
Melting points
Boiling point
Mass and volume
Density
Properties of Matter

Density = mass ÷ volume
Unit is g/cm3

The density of an object is the same
no matter its volume
Density Example Problems
1. What is the density of an object that weights
2200g and has a volume of 100cm3?
2. Gold’s density is 19.3g/cm3 If a gold bar has
mass of 150g what is its volume?
3. Find the density of this cube.
Mass = 30g
Rounding Measurements

Accuracy- how close a measurement is to
the actual value
Rounding Measurements

Precision- how frequently you get the same
measurement when measuring in the same
way
Rounding Measurements

Round the following numbers:

5.76 to the nearest tenths
453 to the nearest tens
3.685 to the nearest hundredths
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Scientific Notation

Used to make numbers easier to deal with
and to keep track of zeros

Only one number before decimal!
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Using calculators with scientific notation:

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Number * 10 ^ (exponent)
Number EE (exponent)
Scientific Notation Examples
Density Lab

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Follow the lab procedure to find the volume of
pennies and metal cylinders
Find the unknown materials used to make the
cylinder objects and the cubes by finding its
density
Assignments

Summary - Describe a way to measure the
volume of a gold necklace.
EXTRA NOTES NOT
APPLICABLE
Significant Figures

Significant figures are used to indicate the
preciseness of measurements
- Significant figures consist of all the digits
known with certainty as well as one
estimated, or uncertain digit
- Use for rounding answers
Rules for Determining
Significant Figures
1. Nonzero digits are always significant
e.g. 643.5 has 4 sig figs
2. Zeros between nonzero digits are
significant
e.g. 909 has 3 sig figs
3. Zeros in front of non zero digits are not
significant
e.g. 0.00034 has 2 sig figs
e.g. 00063
Rules for Determining
Significant Figures
4. Zeros both at the end of a number and
to the right of a decimal point are
significant
e.g. 9.00 has 3 sig figs
5. Assume zero to the right of a number
but to the left of the decimal point is not
significant
e.g. 4000 has 1 sig fig, but 30.0 has 3 sig
figs
Sig Fig Practice
Determine the number of sig figs in each value
a) 4658.2
b) 4006
c) 0.000265
d) 0065
e) 1.0065
f) 3.0
g) 700
Sig Figs in Calculations

When multiplying and dividing, round your
answer to the least number of sig figs in the
equation
Multiplying and Dividing
a) 12 x 4 = ?
b) 1.0 x 623 = ?
Sig Figs in Calculations
When adding and subtracting, round your
answer to the least number of decimal places
in any of the data you are given.
Adding and Subtracting
a)
b)
3.11 + 1.2 = ?
9.899 – 2.23 = ?