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1Chapter 1
Matter and Measurement
Behavior of particles that make up matter is as predicted by Physics Machinery of life is based on structure and function of chemicals
Chemistry: The Central Science
Definitions Chemistry Study of matter and the changes they undergo
Matter Physical material of the universe; Anything that occupies
space and has mass
Changes in matter are tracked by observing changes in its properties. Property Distinguishing characteristic of a particular type of matter
Chemistry matters.
What makes gold a good jewelry material? Where does wax go when you light a candle? Why does alcohol feel cold on the skin? Why do antacids fizz in water? How do cooking on cast iron and stainless
steel cookware differ?
Atoms building blocks of matter Molecules combination of 2 or more atoms
Atoms and Molecules Matter
Properties of matterComposition (kinds of atoms)
Structure (arrangement of atoms)
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2Dimethyl etherbp = -25 C
Ethanolbp = 79 C
Video: States of Matterhttps://www.youtube. com/w atch?f eatur e= player_ emb edd ed &v=s- KvoVzukHo
Assumes the shape and volume of the container it occupies
Retains its own volume and shape
Assumes the shape of the portion of the container it occupies
SOLID
Classifications of Matter According to Physical State
LIQUID GAS
Interaction Strong; locks them in place
Strong; keeps them close together
Insignificant
Order Highly ordered Some disorder Total disorderMovement Fixed in place Some freedom Total freedomSpace Very close Close Far apart
SOLID
Classifications of Matter According to Physical State
LIQUID GAS
ATOMS MOLECULES MOLECULES
Elements composed of one type of atom Compounds composed of 2 or more types of atoms
chemically joined together
Classifications of Matter According to Composition
Pure substance or Substance consists of one type of element or compound
Mixture consists of 2 or more type of substances; composition can be varied
MIXTUREPURE SUBSTANCES
Classifications of Matter Substances Pure H2O (water) , pure NaCl (salt), pure Ag (silver)
Mixtures Salt in water Sterling silver - 92.5% Ag, 7.5% Cu Air - 78% N2, 21% O2, 1% other gases
Elements are chemically joinedConstant composition (NaCl - 60.7% Na, 39.3% Cl)
Elements/components are physically joinedVariable composition
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3Types of Mixture Heterogeneous mixture different composition and
properties throughout
Homogeneous mixture also called solution; uniform throughout
A B
C D E
1. Classify each as pure substance or mixture.2. State the composition for each (i.e. element/compound).
Which of the following figures represents (more than one picture might fit each description) 1) a pure element?2) a mixture of two elements?3) a pure compound?4) a mixture of an element and a compound?
a b c
d e f
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White gold, used in jewelry, contains gold and another white metal such as palladium. Two different samples of white gold differ in the relative amounts of gold and palladium they contain. Both samples are uniform in composition throughout. Classify white gold .
A. elementB. compoundC. homogeneous mixtureD. heterogeneous mixture
Solutions may be:
A. solids, liquids, or gases.B. liquids only.C. liquids or gases.D. none of the above.
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4Properties of Matter
Physical Properties can be observed without changing a substance into another substance
Chemical Properties can only be observed when a substance is changed into another substance
In the following description of the element zinc, indicate which are physical properties and which are chemical properties. Zinc melts at 420 C. When zinc granules are added to dilute sulfuric acid, hydrogen is given off and the metal dissolves. Zinc has a hardness on the Mohs scale of 2.5 and a density of 7.13 g/cm3 at 25 C. It reacts slowly with oxygen gas at elevated temperatures to form zinc oxide, ZnO.
Intensive Properties independent of the amount of substance
Extensive Properties depend upon the amount of substance
Properties of Matter Physical Changes changes in matter that do
not change the composition of the substance
Chemical Changes changes that result in new substances
Physical and Chemical Changes
http://www.youtube.com/watch?v=2KbEV85rJhs
Separation of Mixture ComponentsFiltration
Distillation
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5MeasurementQuantitative properties associated with numbers
Reporting Measured Quantities
NUMBER with UNIT( ex. 2.5 grams )
UnitsEnglish system used in US (lb, miles, inches)Metric system used in scientific measurements (g, m, cm) base units prefixes
milligram, mgkilometer, kmmicrosecond, s
Scientific Notation
a 10b(a times 10 to the power of b)
a = coefficient; a real numberb = exponent; an integer
Example: 1.2 103
Scientific Notation Convenient way of expressing very large or very small numbers
0.00123 1.23 10-326,000 2.6 104
Radius of hydrogen atom 0.000000000120 m = 1.20 10-10 m
Number of molecules in 1 g of water33400000000000000000000 = 3.34 1022
DecimalNotation
ScientificNotation
10000 1 x 104
1000 1 x 103
100 1 x 102
10 1 x 101
1 1 x 100
0.1 1 x 10-1
0.01 1 x 10-2
0.001 1 x 10-3
0.0001 1 x 10-4
Exponent - number of places the decimal point must be shifted to convert between scientific and decimal notations
Positive exponent number is big (greater than 1)Negative number is small (less than 1)
Decimal Notation: 3890000000Scientific Notation: 3.89 x 109
Decimal Notation: 0.000675Scientific Notation: 6.75 x 10-4
Standard scientific notation decimal point after the first non-zero digit
Practice Conversion Decimal to Scientific Scientific to Decimal
Exponent on calculator: EEXP EE
EXP6.02 236.02 1023 6.0223
( 6.02 1023 )( 3.5 108 ) = ?
or or
2.98 1015
9.2 108 = ?
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6UnitsEnglish system used in US (lb, miles, inches)Metric system used in scientific measurements (g, m, cm) base units prefixes
milligram, mgkilometer, kmmicrosecond, s
PrefixesConvert the base units into units that are appropriate for the item being measured.Prefix Abbreviation Meaning ExampleGiga G 109 1 gigameter (Gm) = 1 109 m = 109 m
Mega M 106 1 megameter (Mm) = 1 x 106 m= 106 m
Kilo k 103 1 kilometer (km) = 1 x 103 m = 103 m
100 1 meter (m) = 1 x 100 m = 100 m = 1 m
Deci d 10-1 1 decimeter (dm) = 1 x 10-1 m = 10-1 m
Centi c 10-2 1 centimeter (cm) = 1 x 10-2 m = 10-2 m
Milli m 10-3 1 millimeter (mm) = 1 x 10-3 m = 10-3 m
Micro (mu) 10-6 1 micrometer (m) = 1 x 10-6 m = 10-6 mNano n 10-9 1 nanometer (nm) = 1 x 10-9 m = 10-9 m
Pico p 10-12 1 picometer (pm) = 1 x 10-12 m = 10-12 m
Femto f 10-15 1 femtometer (fm) = 1 x 10-15 m = 10-15 m
1) What is the name given to the unit that equals a) 10-9 gramb) 10-6 secondc) 10-3 meter
2) Express the measurement 6.0 x 103 m using a prefix to replace the power of ten.
3) Use exponential notation to express 4.22 mgin grams.
If a weather forecaster predicts that the temperature for the day will reach 31 C, what is the predicted temperature in K and in F?
K = C + 273.15C = 59 (F - 32)
F = 95 (C) + 32
will be provided in exam
you should be able to derive
Derived Units
Volume Area
length
heig
ht
length
heig
ht
Derived Units Volume
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7Derived Units
Density d =mass
volume
If you have equal masses of the following metals, which will occupy the largest volume?
A. Au, density = 19.3 g/cm3
B. Pb, density = 11.3 g/cm3
C. Ag, density = 10.5 g/cm3
D. Cu, density = 8.92 g/cm3
E. Al, density = 2.70 g/cm3
Calculate the density of mercury if 1.00 x 102 g occupies a volume of 7.36 cm3.
A gold sphere has a radius of 28.9 cm. If the gold has a density of 19.3 g/cm3, what is the mass of the sphere in grams? [The volume of a sphere is V=(4/3)r3.]
How many cm in length is a side of a lead cube that weighs 21.8 g? (The density of lead is 11.3 g/mL.)
Reporting Measured Quantities
NUMBER with UNIT( ex. 2.5 grams )
What difference exists between the measured values 4.0 g and 4.00 g?
Uncertainty in Measurement
Exact numbers values are known exactly (12 eggs in a dozen, 1000 g in 1 kg, 2.54 cm in 1 in, number of objects)
Inexact numbers obtained by measurement (equipment limitation/errors and human errors)
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8Classify each as exact or inexact number.1) the mass of a piece of paper2) the number of inches in a mile3) the volume of coffee in a mug4) the number of pages in the book5) the number of ounces in a pound
Accuracy vs Precision Accuracy - proximity of a measurement to the
true value of a quantity. Precision - proximity of several measurements to
each other.
accurateprecise
not accurateprecise
not accuratenot precise
A student measured the concentration of a solution three times, obtaining values of 0.010 M, 0.060 M, and 0.030 M. The average concentration was thus 0.033 M. The accepted value was 0.034 M. The students data is:
A. accurate and precise.B. not accurate, but precise.C. not accurate and not precise.D. accurate, but not precise.
certain digits + 1 uncertain digit
NUMBER with UNIT
Reporting Measured Quantities
certain digits + 1 uncertain digit
NUMBER with UNIT
Reporting Measured Quantities
What difference exists between the measured values 4.0 g and 4.00 g?
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9Indications of Accuracy
Number of decimal places4.0 vs 4.003.14 vs 3.14159
Number of significant figures4.0 vs 4.00260500 vs 260504
Significant Figures
1. All nonzero digits are significant.2. Zeroes between two significant figures
are themselves significant.3. Zeroes at the beginning of a number are
never significant.4. Zeroes at the end of a number are
significant if there is a decimal point.
How many significant figures are in the measured number 0.082060?
A. 3B. 4C. 5D. 6
Significant zeroes increase the accuracy of the number; they do not change the value.
4 vs 40 vs 4.0
0.4 vs 0.04 vs 0.40
Another way of thinking about zeroes and sig figs... How many significant figures for each of the following numbers?
1) 1.002502) 0.008003) 3.60794) 1.0940 x 109
5) 60.006) 20
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10
Consider the number 82600 How many significant figures? Express in 6 SF. Express in 5 SF. Express in 4 SF.
Express in 2 SF.
Rounding
Application of rounding: Sales tax at 6.5%$25.85 0.065% = $1.68025
Reducing the accuracy of a number while keeping its value similar
Rounding
Think of the two numbers closest to the given number that has the needed number of sig figs or decimal places. The correct rounded number is the one closer
to the original number.
Decide which is the last digit to keep. Leave it the same if the next digit is less than 5
(round down) Increase it by 1 if the next digit is 5 or more
(round up)OR
1) $1.68025 to 2 DP2) 82600 to 2 SF3) 26538 to 4 SF4) 1855.1 to 3 SF5) 8.622 x 104 to 2 SF6) 0.02158 to to 3 SF7) 10.3 to 2 SF
Round the following numbers to the indicated number of significant figures
Significant Figures in Calculations
32.7658 m 2.38 m = 30.3858 m12.56 km 0.15 h = 83.733333333333333 km/h
Addition and Subtraction = LNDP Least number of decimal places
Multiplication and Division = LNSF Least number of significant figures
6.03 grams + 7.1 grams = ?
A. 13 gramsB. 13.1 gramsC. 13.13 gramsD. 13.130 grams
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11
6.03 grams / 7.1 milliliters = ?
A. 0.8 grams/milliliterB. 0.85 grams/milliliterC. 0.849 grams/milliliterD. 0.8492957 grams/milliliter
Mixed Operations1) (1.978 1.2) + 12.45 = ?
2) How many significant figures should be shown for the calculation ?
A. 1B. 2C. 3D. 4E. 5
1.25 + 0.452.734
A bakery measured the mass of a whole cake as 0.870 kg. A customer bought one slice of the cake and measured the mass of the slice as 0.1151 kg. What is the mass of the remaining cake, without the one slice?
A vessel containing a gas at 25 C is weighed, emptied and then reweighed as depicted in the figure below. Calculate the density of the gas at 25 C.
Dimensional Analysis
Problem solving approach where the units are carried through all calculations
Used in converting one quantity from a given unit to another unit by utilizing conversion factors(e.g., 1 in. = 2.54 cm)
Given:
Find:
cm
in
LENGTH1 mi = 5280 ft = 1.6093 km1 m = 1.0936 yd1 in = 2.54 cm1 = 10-10 m
MASS1 lb = 453.59 g = 16 oz1 amu = 1.660538782 x 10-24 g
VOLUME1 gal = 4 qt = 3.7854 L1 in3 = 16.4 cm3
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12
Dimensional Analysis
given unit = desired unit desired unitgiven unit
conversion factor
Example: Convert 15 cm to in.Recall: 1 in = 2.54 cm
Given:
Find:
cm
in
Unit Conversion
Dimensional Analysis: Unit Conversion
Given:
Find:
m
in
m
cm
in
1 cm = 10-2 m
1 in = 2.54 cm
Example: Convert 8.00 m to inches. convert m to cm
convert cm to in
1) How many yd is 350 cm?
2) What is the area in cm2 of a square tile with a side measuring 2.0 in?
3) How many in3 is 1.5 gal?
4) If an automobile is able to travel 254 mi on 11.2 gal of gasoline, what is the gas mileage in km/L?
5) The average speed of a nitrogen molecule in air at 25 C is 515 m/s. Convert this speed to miles per hour.
If it takes 0.125 hectare of land to raise one sheep, how many sheep can be raised on 8.1 acres? (1 hectare = 2.47 acres)
Dimensional Analysis: Problem Solving Many problems can be treated like unit conversion and solved by dimensional analysis.
Get the important informationWhat is the ending (required) quantity or unit?What is the starting (given) quantity or unit?How do I find the conversion factors?
Set up the dimensional analysis
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13
1) The recommended adult dose of Elixophyllin, a drug used to treat asthma, is 6 mg/kg of body mass. Calculate the dose in mg for a 185-lb person.
2) 1 pound of coffee beans yields exactly 50 cups of coffee (4 cups = 1 qt). How many milliliters of coffee can be obtained from 1 g of coffee beans?
3) The mileage of your car is 14 km/L of gas. Gas costs $3.29/gal. How many miles could you drive for $20.00?
4) The density of benzene is 0.879 g/mL.Calculate the mass in grams of 1.00 qt of benzene.
