Transcript Chemistry 140/145

CHEMISTRY 140/145
TCHS
Charles Lee-Instructor
Hopkinsville Community
College
Chapter 1: Matter, Measurements,
and Calculations
•1.1 What Is Matter?
•When you have
completed your study
of this chapter, you
should be able to:
LEARNING OBJECTIVES/ASSESSMENT
• 1. Explain what matter is. (Section 1.1; Exercise 1.2)
• 2. Explain differences between the terms
chemical as applied to:
physical and
• a. Properties of matter (Section 1.2; Exercises 1.10 b & c)
• b. Changes in matter (Section 1.2; Exercises 1.8 a & b)
• 3. Describe matter in terms of the accepted scientific
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model. (Section 1.3; Exercise 1.12)
4. On the basis of observation or information given to
you, classify matter into the correct category of each of
the following pairs:
a. Heterogeneous or homogeneous (Section 1.4; Exercise
1.22)
b. Solution or pure substance (Section 1.4; Exercise 1.24)
c. Element or compound (Section 1.4; Exercise 1.18)
LEARNING OBJECTIVES/ASSESSMENT
• 5. Recognize the use of measurement units in everyday
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activities. (Section 1.5; Exercise 1.28)
6. Recognize units of the metric system, and convert
measurements done using the metric system into related units.
(Section 1.6; Exercises 1.30 and 1.40)
7. Express numbers using scientific notation, and do
calculations with numbers expressed in scientific notation.
(Section 1.7; Exercises 1.48 and 1.60)
8. Express the results of measurements and calculations using
the correct number of significant figures.
(Section 1.8; Exercises 1.64 and 1.66)
9. Use the factor‐unit method to solve numerical problems.
(Section 1.9; Exercise 1.82)
10. Do calculations involving percentages. (Section 1.10;
Exercise 1.92)
11. Do calculations involving densities. (Section 1.11; Exercise
1.98)
Chapter 1: Matter, Measurements,
and Calculations
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CHAPTER OUTLINE
1.1 What Is Matter?
1.2 Properties and Changes
1.3 A Model of Matter
1.4 Classifying Matter
1.5 Measurement Units
1.6 The Metric System
1.7 Large and Small Numbers
1.8 Significant Figures
1.9 Using Units in Calculations
1.10 Calculating Percentages
1.11 Density
1.1 Explain what matter is.
• matter - anything that occupies space
and has mass
• mass - the amount of matter(atoms) a
body possesses
• weight - a measure of the earth’s
gravitational attraction on matter
1.2 Properties of matter. Explain differences
between the terms physical and chemical as
applied to:
• Physical Properties -
those which can be
determined without
a change in identity
• Examples
• length
• Chemical Properties
- ability of a
substance to
undergo a change in
identity
• Examples
• mass
• iron rusts
• color
• milk sours
• silver tarnishes
1.3 Describe matter in terms of the
accepted scientific model.
• liquid - definite volume, indefinite
shape
• solid - definite shape and volume
• gas - neither definite shape nor
definite volume
1.4 On the basis of observation or
information given to you, classify matter
into the correct category of each of the
following pairs:
• a. Heterogeneous or homogeneous
• b. Solution or pure substance
• c. Element or compound
Classification of Matter
MATTER
seperated by phycical means
YES
NO
mixture
pure substance
UNIFORM COMPOSITION?
DECOMPOSED CHEMICALLY?
YES
NO
YES
NO
HOMOGENEOUS
HETEROGENEOUS
COMPOUND
ELEMENT
1.5 Recognize the use of
measurement units in everyday
activities.
• Measurements are essential to ensuring fairness in
sports.
• SI measurements are used on everything from
keeping accurate event times, the correct pressure
of sports balls, and measuring competition
distances.
• The most frequent measurements made in the home
are those used for cooking and baking.
• Metric "cup and spoon" measures are only slightly
larger than, and can often be used interchangeably
with, the customary "cup and spoon" measures.
Metric Chocolate Chip Cookies
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Ingredients:
550 mL unsifted flour
5 mL baking soda
5 mL salt
250 mL butter or margarine, softened
175 mL granulated sugar
175 mL firmly packed brown sugar
5 mL vanilla extract
Preheat the oven to 190 ºC. In small bowl, combine flour,
baking soda, and salt; set aside. In large bowl, combine
butter, sugar, brown sugar, and vanilla; beat until creamy.
Beat in eggs. Gradually add flour mixture; mix well. Stir in
chocolate chips and nuts. Using 5 mL measure, drop by
rounded measures into ungreased cookie sheet. Bake 8 to 10
minutes.
Makes 100 (5 cm) cookies
1.6 Recognize units of the metric system, and convert
measurements done using the metric system into
related units.
• SI(International
• Quantity
System) Fundamental Units
Unit
• length
meter
• mass
kilogram
• time
second
• temperature
Kelvin
• amount of matter mole
Symbol
m
Kg
s
K
mol
Derived Units
• derived unit - a unit obtained by combinations of
fundamental units
• Example - volume (cm3)
• V=lXwXh
• V(cm3) = (cm) X (cm) X (cm)
• 1cm3 = 1mL
• How many liters in one cubic meter?
1.7 Express numbers using scientific notation, and do
calculations with numbers expressed in scientific notation.
• scientific notation - an expression of numbers as
powers of 10
• Express 93,000,000 in scientific notation
•93,000,000
• Express 0.000 000 000 189 in scientific notation.
•0.000 000 000 189
1.8 Express the results of measurements and
calculations using the correct number of
significant figures.
• The following rules are used to determine
the number of significant digits.
• 1. Nonzero digits are always significant.
• 2. All final zeros after the decimal point are
significant.
• 3. Zeros between two other significant digits
are always significant.
• 4. Zeros used solely for spacing the decimal
point are not significant.
How many sigdigs in the following?
•1. 0.0003100500
•2. 1,000,000,000
•3. 1.00004
•4. 0.00000001000
•5. 6.404 X 106
Operations With Significant Digits
• Addition and Subtraction
• The answer should be rounded off so that
the final digit is in the same place as the
leftmost uncertain digit.
• Example
• 34.9
• +4.56
• 39.46.......the correct answer is 39.5
Operations With Significant Digits
• Multiplication and Division
• The answer should be rounded off to
the same number of significant digits
as the measurement with the least
number of significant digits.
• Example
• 2.34 X 6.5 = 15.21
• the correct answer is 15
Perform the indicated operations
using sidigs.
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23.67 + 4.5 =
4.5 – 3.888 =
(3.5 X 102) – (2.3 X 102)
(3.5 X 102) X (2.3 X 102)
(3.5 X 102) ÷ (2.3 X 102)
9. Use the factor‐unit method to solve
numerical problems.
• 1. How many seconds in 1 year, 365 days?
• 2. Dr. Michael prescribes 300 mg a day of
medicine to a patent. Each pill has 15 mg of
medicine. How many pills will the patient
need for 7 days?
• 3. A solution contains 5 grams of glucose
per 100 milliliters. Each mole of glucose
weighs 180 grams. How many moles are
there in 200 milliliters of the glucose
solution?
1.10 Do calculations involving
percentages.
• How do we measure accuracy?
• accuracy - the nearness of a measurement to an
accepted value
• precision - the agreement between a set of
measurements
Percentage Error
O-A
%E = ------------ X 100%
A
O - observed value
A - accepted value
How do we determine precision?
1.11 Do calculations involving
densities.
• density - the mass per unit volume of a
material
• density = mass/volume
• D(g/cm3) = m(g) / V(cm3)
• D(g/mL) = m(g) / V(mL)
• For gases
• D(g/L) = m(g) / V(L)
Sample Density Problem
• Problem: Calculate the density of 10g of a material
occupying a volume of 2.5mL. (10 pts)
• D = m/V , m = 10g, V = 2.5mL
5 pts
• D = 10g / 2.5mL
2 pts
•D=4
g/mL
• (1pt) + (2pts) =
3pts
Sample Problems
• Suppose you performed an experiment and
found the volume of a 10g sample of
aluminum to be 3.5mL.
• Calculate the density of the sample using your
data.
• The accepted density of aluminum is 2.7g/mL.
Calculate the percentage error of your
measurements.
A fruit drink is made by mixing 1.0 L of water with
25g of solid mix. What percent of the mass of the
mixture is solid fruit mix?