Intro To Chemistry

Element QuizYou will be required to memorize the following elements for the Quiz on MondaySpelling Counts!!

1-36, 47, 50, 53, 54, 56-57, 7478-80, 82, 86,92, 94

Elements 92 UraniumU

94 Plutonium Pu

Is the study of the composition of matterand the changes that matter undergoes, and the energy associated with these changes.

Scientific Approach: Developing a ModelObservations :Natural phenomena and measured events; universally consistent ones can be stated as a natural law.

Alchemist at Work(1800s)Early chemistsDealt with religion, medicine, magic and scienceKept inaccurate records due to fearFour elementsEarthAirFireWater

MeasurementQuantitiveGive results in a definite form Usually involving numbers20 grams, 273 K

Qualitativegive results in a descriptive non-numeric form

Physical Quantity (Dimension)Unit NameUnit Abbreviationmassmeterkglengthkilogramm

Three targets with three arrows each to shoot.Can you hit the bull's-eye?Both accurate and precisePrecise but not accurateNeither accurate nor preciseHow do they compare?Can you define accuracy and precision?

Accuracy vs. PrecisionAccuracy - how close a measurement is to the accepted valuePrecision - how close a series of measurements are to each otherACCURATE = CORRECTPRECISE = CONSISTENT

Accuracy & PrecisionAccuracyHow close a measurement is to the actual dimension or true value of what is measuredPrecisionReproducibility of the measurement

Figure 1.16Precision and accuracy in the laboratory.

Scientific NotationIn exponential form, the number is written as the product of 2 numbers the coefficient and a power of 101. The coefficient should always be a number greater than or equal to one and less than 102. The subscript indicates how many times the number must be multiplied by 10

Examples12 000 001.2 x 107

85 1308.513 x 104

0.000727.2 x 10-4

Significant FiguresIncludes all digits that can be known precisely plus a last digit that must be estimated

Significant FiguresIndicate precision of a measurement.Recording Sig FigsSig figs in a measurement include the known digits plus a final estimated digit2.35 cm

The number of significant figures in a measurement depends upon the measuring device.Figure 1.1432.3 oC32.33 oC

Rules for Sig Figs1. Every non-zero digit in a recorded measurement is significant 24.7 ml

2. Zeros between nonzero numbers are significant7003 ml

3. Zeros appearing in front of all nonzero digits are not significant. 0.0071 ml

4. Zeros at the end of a number and to the right of a decimal are significant 43.00

5. Zeros at the end of a measurement (no decimal shown)Are confusing 300 m 7000m

Atlantic/Pacific RuleIf decimal is Absent begin counting of the Atlantic side starting with the first whole numberIf decimal is Present, begin counting on the Pacific side starting with first whole number

QUIZDetermining the Number of Significant FiguresFor each of the following quantities, determine the number of significant figures in each quantity. SOLUTION:(b) 0.1044 g(a) 0.0030 L(c) 53,069 mL(e) 57,600. s(d) 0.0000 4715 m(f) 0.0000007160 cm3

Sig Figs In CalculationsAn answer cannot be more precise than the least precise measurement

Addition and SubtractionThe answer of an addition or subtraction can have no more digits to the right of the decimal point than are contained in the measurement with the least number of digits to the right of the decimal point

12.52m + 349.0m + 8.24m = 369.76m369.8 or 3.698 x 102

74.626m 28.34 = 46.28646.29 or 4.629 x 101

Significant FiguresCalculating with Sig Figs (cont)Add/Subtract - The # with the lowest decimal value determines the place of the last sig fig in the answer. 3.75 mL+ 4.1 mL 7.85 mL

7.9 mL 3.75 mL+ 4.1 mL 7.85 mL

Practice61.2m + 9.35 + 8.6m

9.44 2.11

1.36 + 10.17

34.61 17.3

Answers79.2

7.33

11.53

17.3

Multiplication & DivisionThe answer must contain no more significant figures than the measurement with the least number of SF

a) 7.55m x 0.34 = 2.567m2 = 2.6m2B) 2.10m x 0.70m = 1.47m2 = 1.5m2C) 2.4526 / 8.4 = 0.291 976m = 0.29mD) 0.365m /0.0200 = 18.25m = 18.3m

You try!8.3m x 1.22m =

1.8 x 10-3m x 2.9 x 10-2m

8432 / 12.5

5.3 x 10-2 / 0.255

Answers1.0 x 101 m2

5.2 x 10-5 m2

6.75 x 102 m

0.21m

Math Rules For Chemistry:

1) N3: No Naked Numbers. All measurements and answers to math problems must have units written after the numbers.

2) No Work, No Credit. You must show all of the following when doing math problems: the equation you are going to use, the equation rearranged algebraically to solve for the variable you are looking for, the rearranged equation with numbers and units substituted in for all of the variables (numerical setup) and the final answer, rounded properly with units after.

3) The number should also be as precise as the measurement!

Percent ErrorIndicates accuracy of a measurement

Percent ErrorA student determines the density of a substance to be 1.40 g/mL. Find the % error if the accepted value of the density is 1.36 g/mL.

Physical Quantity (Dimension)Unit NameUnit AbbreviationmassmeterkglengthkilogrammenergyjouleJ

SI Units in metric (based on powers of 10)PrefixSymbolFactor

Metric System1. length The meter is the basic unit of length. The meter stick is divided into 100 equal parts each 1 cm in length1km = 103 m micro meter 10-6 m2. MassThe kilogram is the basic unit of mass1kg is equal to the mass of 1L of water at 4 C therefore 1g of water equal to the volume of 1cm3(ml) at 4 C3. VolumeThe space occupied by matter. Derived from measurement of length. 1L = 1000cm3 1ml = 1cm3

SI Prefix Conversions1.Find the difference between the exponents of the two prefixes.2.Move the decimal that many places.

SI Prefix ConversionsPrefixSymbolFactormove leftmove right

SI Prefix Conversions1) 20 cm = ______________ m2) 0.032 L = ______________ mL3) 45 m = ______________ nm4) 805 dm = ______________ km0.20.080545,00032

SI Prefix Conversions1) 20 cm = ______________ m2) 0.032 L = ______________ mL3) 45 m = ______________ nm4) 805 dm = ______________ km0.20.080545,00032

Prefix

Prefix Symbol

Word

Conventional

Notation

Exponential

Notation

tera

T

trillion

1,000,000,000,000

1x1012

giga

G

billion

1,000,000,000

1x109

mega

M

million

1,000,000

1x106

kilo

k

thousand

1,000

1x103

hecto

h

hundred

100

1x102

deka

da

ten

10

1x101

-----

----

one

1

1x100

deci

d

tenth

0.1

1x10-1

centi

c

hundredth

0.01

1x10-2

milli

m

thousandth

0.001

1x10-3

micro

millionth

0.000001

1x10-6

nano

n

billionth

0.000000001

1x10-9

pico

p

trillionth

0.000000000001

1x10-12

femto

f

quadrillionth

0.000000000000001

1x10-15

DensityDensity usually decreases as temperature increases because volume increases making the mass more spread out, but the total mass stays the sameOne exception!!

WATER Density decreases as the temperature decreases in water

Substance Physical State Density (g/cm3)*At room temperature(200C) and normal atmospheric pressure(1atm).

ProblemA copper penny has a mass of 3.1 grams and a volume of 0.35cm3 What is the density of copper?D = m/v

D= 3.1 g/0.35cm3 = 8.8571cm3= 8.9g/cm3 (2sf)

Problem A plastic ball with a volume of 19.7 cm has a mass of 15.8g. Would this ball sink or float in a container of gasoline? (gasoline's density is 0.69)

D = 15.8 g/19.7cm3 = 0.802 g/cm3

Sample problemCalculating Density from Mass and LengthPROBLEM:Lithium (Li) is a soft, gray solid that has the lowest densityof any metal. If a slab of Li weighs 1.49 x 103 mg and has sides that measure 20.9 mm by 11.1 mm by 11.9 mm, what is the density of Li in g/cm3 ?

Density ProblemsA 1.00 Liter sample of carbon tetrachloride weighs 1.58 Kg. What is the density of this substance in g/cm3?Find the mass, volume, or density of a substance when two of these values are known. Examples;Given: mass = 20g; volume = 10ml; find densityGiven: density = 2 g/ml; volume = 10ml; find massGiven: mass = 20g; density = 2g/ml; find volume

TemperatureTemperature is the degree of hotness or coldness of an object. Heat travels from the hot object to cold object. Heat transfer occurs when two objects at different temperatures contact each other.

Heat travels from the object at high temperature to the one at low temp.

Temperature Scales

Notice that 1 kelvin = 1 degree CelsiusBoiling point of waterFreezing point of waterCelsiusKelvinFahrenheit

Calculations Using TemperatureGenerally require temps in kelvinsT (K) = t (C) + 273Body temp = 37 C + 273 = 310 KLiquid nitrogen = -196 C + 273 = 77 K

Temperature Scales and InterconversionsKelvin ( K ) - The Absolute temperature scale begins at absolute zero (considered the lowest possible temperature 0 K)and only has positive values.Celsius ( oC ) - The temperature scale used by science, formally called centigrade, most commonly used scale around the world; water freezes at 0oC, and boils at 100oC.Fahrenheit ( oF ) - Commonly used scale in the U.S. for our weather reports; water freezes at 32oF and boils at 212oF.Kelvin = oC + 273.15 oC = Kelvin - 273.15oF = (9/5) oC + 32oC = [oF - 32 ] 5/9

Kelvin ScaleK = C + 273

C = K 273

The bp of air is 87K. What is the bp in C?

Ethylene glycol is a major ingredient in antifreeze. It boils at 199C. What is bp in K? F?

Converting Units of TemperatureA child has a body temperature of 38.7 oC.(a) If normal body temperature is 98.6 oF, does the child have a fever?(b) What is the childs temperature in Kelvin?

Figure 1.12The freezing and boiling points of water.

Dimensional AnalysisConversion FactorsOne dollar = 4 quarters = 10 dimes

One meter = 10 dm= 100cm=1000mmA ratio of 2 of these will equal one

100cm/1m = 1 1m/100cm = 1

Dimensional AnalysisThe Factor-Label MethodUnits, or labels are canceled, or factored out

These equivalent ratios are called conversion factorsThe measurement on the top (numerator) is equivalent to the measurement in the denominator Write 2 possible conversion factors for each pair of unitsA) kilograms and grams1000g/1kg or 1kg/1000g

Problems

1L = 1mlMeter & micrometersGrams and centigramsGrams of water , ml of water

Solutions1L /103ml103ml /1L

1m/1 000 000 106microm/1m

1g/100cg100cg/1g

1g H2O/1ml H2O1ml H2O/1gH2O

How many minutes are in 2.5 hours?

Conversion factor 2.5 hr x 60 min = 150 min 1 hr cancel

By using dimensional analysis / factor-label method, the UNITS ensure that you have the conversion right side up, and the UNITS are calculated as well as the numbers!

Learning Check

How many seconds are in 1.4 days?

Unit plan: days hr min seconds

1.4 days x 24 hr x ?? 1 day

Problems0.001348 g to mg

500ml to liters

5.5 cm to km

3560 to mm

Given that 1L = 1dm3Calculate the number of liters inA) 1m3B) 1cm3C) 1mm3

Solve rate conversion problems using dimensional analysisIf a car gets 30.0 miles/gallon of gasoline, how many kilometers could it travel on 1 liter of gasoline? (1.61 Km = 1 mile; 1 gal = 4 qt; and 1.06 qt = 1.0L)

If you could count at the rate of 2 numbers every second, how many days would it take to count to 1 million?Calculate the # of lab reports Mrs. Connelly will have to grade during the school year if you students complete 30 experiments. Mrs Connelly has 4 classes of 27 students each?

How many cubic millimeters (mm3) are there in an object whose volume is found to be 8.3014 x 10-2 cubic meter (m3)?Calculate the number of cubic centimeters (cm3) there are in 0.500 cubic decimeters (dm3)

Calculate the volume, in cubic decimeters (dm3) , of a rectangular object that is 1.07m long, 0.2233 wide, and 0.895 m high?

GRAPHINGRelationships: Graphs show relationships between the dependent and the independent variable. This can be used to make predictions about behavior of physical and chemical phenomena.Direct Relationship: As the independent variable is increased, the dependent variable also increases.Indirect (Inverse) Relationship: As the independent variable is increased, the dependent variable decreases

Graphs should contain the following features:1) X and Y axes with the independent variable in the X axis (with units) and the dependent variable on the Y axis (with units).2) A numerical scale representing uniform increases in each variable.3) A title: (Dependent Variable) vs. (Independent Variable) - for example 1, above, this would be Reaction Rate vs.Temperature.4) Data points, circled with point protectors. These circles serve two purposes: to make the point more visible and to represent the margin of error associated with estimated digits.5) A line either connecting the data points or a best fit line.