Name __________________________________________________ Honors Chemistry Summer Assignment

HONORS CHEMISTRY – SUMMER ASSIGNMENT In chemistry, you will be learning the scientific names of elements and compounds, as well as completing many mathematical calculations of chemical quantities. Your summer assignment begins with learning some of these facts. You will be quizzed on the names and symbols of the elements and polyatomic ions in this packet throughout the year (given the chemical symbol provide the properly spelled name or given the name provide the proper

chemical symbol). You must know the spelling and symbol. All elements are to be written as shown on this list with a capital letter as the first letter and lowercase letter as the second letter. Do not write in all caps, or in cursive. You will also be quizzed on the metric prefixes, their meanings and the ability to convert between them. Assignment:

1. Make flash cards (on index cards not cut strips of paper) of the metric system prefixes at the bottom of this page, as well as the elements and the polyatomic ions listed on the next page. a. For the metric system, put the prefix on one side and the numerical meaning on the other. b. For elements and ions, put the symbol on one side and the name on the other. Please put only one element or ion per card. c. You will be given a homework grade for the flash cards. 2. Complete the attached worksheet packet, to be handed in the first day of school as a second homework grade. You have been given a periodic table in case there are elements in the worksheet that are not on your list to memorize. Assume you have Chemistry the first day of school, do not wait to find out your schedule! Bring your cards and packet to school!

Metric Prefixes

Prefix Numerical Meaning

Kilo- (K___) 1000 (which is 103) BASE UNIT The main metric unit (meter (m), liter (l) , gram (g), etc.) deci- (d___) 0.1 (which is 10-1 or a tenth) centi- (c___) 0.01 (which is 10-2 or a hundredth) milli- (m___) 0.001 (which is 10-3 or a thousandth) micro (µ___) 0.000001 (which is 10-6 or a millionth)

Name __________________________________________________ Honors Chemistry Summer Assignment

ELEMENTS

Aluminum Al Argon Ar Barium Ba

Beryllium Be Bismuth Bi Boron B

Bromine Br Calcium Ca Carbon C Cesium Cs Chlorine Cl

Chromium Cr Cobalt Co Copper Cu Fluorine F

Gold Au Helium He

Gallium Ga Germanium Ge Hydrogen H

Iodine I Iron Fe Lead Pb

Lithium Li Magnesium Mg Manganese Mn

Mercury Hg Neon Ne Nickel Ni

Nitrogen N Oxygen O

Phosphorus P Platinum Pt Potassium K

Radon Rn Rubidium Rb Scandium Sc

Silicon Si Silver Ag

Sodium Na Strontium Sr

Sulfur S Titanium Ti

Tin Sn Uranium U Xenon Xe Zinc Zn

POLYATOMIC IONS

Polyatomic ions are groups of multiple atoms that have a charge (positive or negative). The symbols shown below tell you what elements are in the ion, how many atoms of each, and the charge. For example: NH4+1 contains a nitrogen atom, four hydrogen atoms and the entire group has a charge of +1.

Memory Hint: If you have two ions with similar names and the only difference is the number of oxygen atoms in your ion: -ite means smaller number of O -ate means larger number of O Hypo- (smallest) and Per- (largest) are used if there are four ions with similar names and different numbers of oxygen. ION NAME NH41+ ammonium ClO1- hypochlorite ClO21- chlorite ClO31- chlorate ClO41- perchlorate CN1- cyanide OH1- hydroxide IO31- iodate NO31- nitrate

ION NAME NO21- nitrite MnO41- permanganate CO32- carbonate O22- peroxide SO42- sulfate SO32- sulfite PO43- phosphate CH3COO1- acetate

Name __________________________________________________ Honors Chemistry Summer Assignment

Memorization Tips: Elements/Symbols Over the years, my students and I have developed several unique ways to help us remember the symbols for the elements. Be warned - some are a little out there!

Silver Ag If a person who is expecting a present of a gold necklace receives a silver one. He might say, “Ag, I didn’t want silver!”

Gold Au “Hey you, I want that gold necklace!” Said with “Hey you” sounding like Au.

Bromine Br That brother of mine - Bro of mine! Calcium Ca “Caws give milk!” Pronounced with an accent to make cows sound like

it’s spelled with an A. Chlorine Cl “You Clean with chlorine!” Iron Fe “Fe, Fi, Fo, Fum, I’m an iron man!” Helium He If you breathe in helium, you will laugh! He, He, He! Mercury Hg Greek mythology - Hg stands for Helmet guy! Potassium K You will get Kicked out of school for the double nasty! You can’t do the

first three letters and cannot say the next three! Sodium Na “Naw, I don’t want any sodium!” Nickel Ni “Nick owes me a nickel!” Oxygen O “Open your mouth wide to take in oxygen!” Lead Pb Pencil broke! Silicon Si Silly con! Tin Sn A tin roof gets hot in the Sun. Manganese Mn Take first three letters - Man Magnesium Mg Take first three letters – Mag

Name __________________________________________________ Honors Chemistry Summer Assignment

Fill in the missing symbol/name of the element. The date of discovery and the origin of the name are included for your information only. You will only be responsible for the names and symbols.

Symbol Name Date Origin of Name aluminum 1825 Latin, alumen = astringent taste

Ar 1894 Greek, argos = neutral or inactive barium 1808 Greek, baryos = heavy

Bi ~1450 German, wismut = white mass boron 1808 Arabic, bawraq

Br 1826 Greek, bromos = stench C B.C. Latin, carbo = coal Cs 1860 Latin, caesius = blue

chlorine 1808 Greek, chloros = green gas Cr 1797 Greek, chroma = color cobalt 1735 Greek, cobolos = goblin

Cu B.C. Latin, cuprum fluorine 1886 Latin, fluere = to flow

Ga 1875 Latin name, Gaul, of France germanium 1886 country, Germany

Au B.C. Latin, aurum He 1895 Greek, helios = the sun H 1766 Greek, hydro genes = water former I 1811 Greek, iodos = violet color

Fe B.C. Latin, ferrum lead B.C. Latin, plumbum magnesium 1803 Latin, magnesia = a place in Asia Minor

Mn 1774 Latin, magnes = magnet Hg B.C. Latin, hydragyrum = god and planet

neon 1898 Greek, neo = new nickel 1750 German, goblin nitrogen 1772 Latin, nitro = native soda and gen = born

O 1771 Greek, oxys = sharp and gen = born P 1669 Greek, phosphoros = light bringer

Name __________________________________________________ Honors Chemistry Summer Assignment

platinum 1735 Spanish, plata = silver K 1807 Latin, kalium radon 1900 originates from radium

Rb 1860 Latin, rubidius = red scandium 1879 Scandanavian peninsula by its discoverer silicon 1823 Latin, silex = flint

Ag B.C. Latin, argentum sodium 1807 Latin, natrium

Sr 1808 town of Strontian, Scotland sulfur B.C. Latin, sulphur tin B.C. Latin, stannum

Ti 1791 Greek mythology, first sons of earth U 1789 planet Uranus Xe 1808 Greek, xenos = strange

zinc B.C. German, zink = like tin Write your answers in the blanks below

1. Mg is _____________

2. Magnesium is _____________

3. Aluminum is _____________

4. Silicon is _____________

5. Fe is _____________

6. H is _____________

7. Cu is _____________

8. N is _____________

9. C is _____________

10. Helium is _____________

11. Oxygen is _____________

12. Copper is _____________

13. Calcium is _____________

14. Iron is _____________

15. Potassium is _____________

16. Hydrogen is _____________

17. Carbon is _____________

18. Nitrogen is _____________

19. O is _____________

20. F is _____________

21. Fluorine is _____________

22. Na is _____________

23. Sodium is _____________

Name __________________________________________________ Honors Summer Assignment

Spell the name of the following ions correctly: 1. NO21- __________________________________ 2. CO32- __________________________________ 3. ClO31- __________________________________ 4. OH1- __________________________________ 5. PO43- __________________________________ 6. NH41+ __________________________________ 7. SO42- __________________________________ 8. CN1- __________________________________ 9. CH3COO1- ____________________________ 10. O22- __________________________________ 11. NO31- __________________________________ 12. IO31- __________________________________ 13. MnO41- ____________________________ 14. ClO21- __________________________________ 15. O22- __________________________________

Write the symbol and charge of the following ions. 1. phosphate ____________________________ 2. sulfate ____________________________ 3. cyanide ____________________________ 4. hydroxide ____________________________ 5. carbonate ____________________________ 6. nitrate ____________________________ 7. acetate ____________________________ 8. chlorate ____________________________ 9. perchlorate ____________________________ 10. hypochlorite ____________________________ 11. iodate ____________________________ 12. nitrite ____________________________ 13. sulfite ____________________________ 14. peroxide ____________________________ 15. permanganate _______________________

Name __________________________________________________ Honors Summer Assignment

Polyatomic Ion Puzzle

Across

2. chlorite

3. peroxide

5. chlorate

7. sulfite

8. permanganate

10. carbonate

11. nitrite

14. nitrate

15. sulfate

Down

1. hypochlorite

2. acetate

4. phosphate

6. iodate

9. hydroxide

10. perchlorate

12. cyanide

13. ammonium

DIRECTIONS: When writing symbols for this puzzle, write the number before the + or – for the charge. For example, write N O 3 1 - NOT N O 3 - 1

Name __________________________________________________ Honors Summer Assignment

Polyatomic Ion Puzzle

Across

2. ClO1-

3. CN1-

4. ClO31-

6. PO43-

11. IO31-

13. CO32-

14. MnO41-

15. NO21-

Down

1. SO32-

5. CH3COO1-

6. ClO41-

7. SO42-

8. OH1-

9. ClO21-

10. NH41+

12. O22-

15. NO31-

Name __________________________________________________ Honors Summer Assignment

1 2 3 4

5

6

7

8 9

10 11

12 13 14

15 16

17

18

19 20 21

22 23

24

25

26

Across 5 He (6) 6 Ca (7) 8 O (6) 9 Fe (4) 10 Cu (6) 12 K (9) 15 Na (6) 16 Au (4) 18 H (8) 19 Be (9) 24 Cl (8) 25 S (7) 26 Ne (4)

Down 1 N (8) 2 Ni (6) 4 As (7) 7 Zn (4) 11 P (10) 12 Pu (9) 13 Ar (5)

14 Si (7) 17 F (8) 19 B (5)

20 Pb (4) 21 Hg (7) 22 Ag (6) 23 C (6)

25

Nam

e __________________________________________________ Honors Sum

mer A

ssignment

Periodic Table of the Elements Q

uiz

Fill in

the b

lanks w

ith th

e ato

mic sym

bols o

f the first 2

0

elemen

ts. (You

do n

ot n

eed to

ad

d th

e atomic n

um

ber,

weig

ht o

r nam

e.) Write th

e elem

ent n

ames in

the b

lanks

belo

w.

Key:

elem

ent name

atomic num

ber

symbol

atomic w

eight

scandium

21

Sc 44.95591

titanium

22

Ti 47.867

vanadium

23

V

50.9415

chromium

24

Cr

51.9961

manganese

25

Mn

54.93805

iron 26

Fe 55.845

cobalt 27

Co

58.9332

nickel 28

Ni

58.6934

copper 29

Cu

63.546

zinc 30

Zn 65.409

gallium

31

Ga

69.723

germanium

32

Ge

72.64

arsenic 33

As

74.9216

selenium

34

Se 78.96

bromine

35

Br 79.904

krypton 36

Kr

83.798 rubidium

37

Rb

85.4678

strontium

38

Sr 87.62

yttrium

39

Y

88.90585

zirconium

40

Zr 91.225

niobium

41

Nb

92.90638 molybdenum

42

Mo

95.94

technetium

43

Tc [98]

ruthenium

44

Ru

101.07

rhodium

45

Rh

102.9055

palladium

46

Pd 106.42

silver 47

Ag

107.8682

cadmium

48

Cd

112.411

indium

49

In 114.818

tin 50

Sn 118.710

antimony

51

Sb 121.760

tellurium

52

Te 127.60

iodine 53

I 126.9045

xenon 54

Xe

131.293 (1)

(2) (3) (4) (5)

__________________

__________________

__________________

__________________

__________________

(6) (7) (8) (9) (10)

__________________

__________________

__________________

__________________

__________________

(11)

(12)

(13)

(14)

(15)

__________________

__________________

__________________

__________________

__________________

(16)

(17)

(18)

(19)

(20)

__________________

__________________

__________________

__________________

__________________

2

Welcome to Chemistry. You will study the composition of matter (anything that has mass and takes up space) and the changes it undergoes. In order to prepare to study this material effectively, you should have some background knowledge. This packet contains that information. This packet should be completed over the summer and returned at the specified time. It is your first assignment and it will be discussed and graded. You may work with classmates, but you will be held responsible for this material, so be sure you understand it. I. Introduction There are 5 divisions of chemistry, and they overlap somewhat:

1. Organic chemistry: the study of substances containing carbon – often living, or once living things

2. Analytical chemistry: the study of the composition of substances – how much of a chemical or substance is present 3. Physical chemistry: the study involving prediction of the behavior of chemicals – why does a substance do what it does under specific conditions or just in general 4. Biochemistry: the study of the chemistry of living organisms – how and why the chemistry of living organisms works and affects lives 5. Inorganic chemistry: the study of substances not containing carbon – nonliving things or things that never lived, and how they interact or react. Questions: Which division or divisions of chemistry might be used to examine: a) The mechanism by which blood clots b) The amount of a toxic substance found in a water supply c) The reason a metal melts at a specific temperature d) The formation of chemical compounds made up of metals

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II.The Scientific Method In order to pursue the study of matter and the changes it undergoes, or to solve other

problems in science, it is important to use a logical and predictable technique. The Scientific Method is one such technique. It is a common sense approach applicable to not only scientific questions, but many other, everyday quandaries as well.

There are variations on the Scientific Method, but most of them contain the following steps: 1. Observations: Something needs explanation – a problem, a question, an issue. 2. Hypothesis: A suggestion which solves the problem, answers the question, explains the issue is offered. It may be termed an “educated guess” because it is based on some logical explanation or suggestion of cause. Often stated as “If ___________, then ___________. 3. Experimentation: The testing of the hypothesis, usually repeated trials are necessary to assure that the results of the tests can be accepted as genuine. 4. Theory: A theory, or explanation of the results of the experiment is offered. The theory is a possible answer, it cannot be proven to be true; it is possible to disprove a theory. Some sources will list a fifth step to the Scientific Method: 5. Scientific Law: A statement is offered which summarizes the results of experiments and observations. A scientific law does not try to explain the results, it merely states what the results are. Questions: 1. Given the following five statements, identify which of the five parts of the Scientific Method they describe. A) Ash trees infested with ash borer insects die. B) Leaves are falling off my ash trees and there are areas of bark which are destroyed. C) Ash trees are infested by ash borer insects in Oakland County. It is possible that my trees are also. D) I will remove the bark in areas of my trees and look for characteristic signs of ash borer disease. I will look at each tree in several spots. E) If my trees have ash borer disease, they would lose their leaves and their bark would be damaged. 2. Write your own example of an observation or problem, and use the five steps of the Scientific Method to solve it.

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III. Dimensional Analysis Many calculations are required in this course. The technique used to solve most problems is called dimensional analysis. It uses conversion factors in order to derive answers. For example, suppose the question was “How many inches are there in 3.5 feet?” There is a defined relationship between feet and inches: 1 foot = 12 inches. If this relationship was written as a fraction it could be said that 1 foot = 1 or, 12 inches = 1. This is true because 1 foot = 12 inches. 12 inches 1 foot Now, returning to my question, and recognizing that multiplying anything by 1 does not change that which is multiplied, I could answer my question using dimensional analysis. 3.5 feet · 12 inches = 42 inches Units of feet/foot cancel, leaving inches. 1 foot 3.5 feet was multiplied by a conversion factor that allowed feet to be converted to inches. This method should be used whenever possible. Always begin these problems with the amount given, above the amount was 3.5 feet. Then use the appropriate conversion factor to convert from the units you have to the units you want. In this example, the desired unit was inches. Remember: the conversion factor is a fraction in which the two components are EQUAL. i.e.: 1 foot = 12 inches. The conversion factor can also be the number required for each, such as: each student requires 2 pencils to take a test. How many pencils are needed if 15 students are taking a test? 15 students · 2 pencils = 30 pencils Units of “student” cancel, leaving 1 student pencils Questions: Use dimensional analysis to solve: 1. How many eggs are there in 6.2 dozen? 2. Each automobile made by Ford requires 4 tires. How many tires are needed to manufacture 259 cars? 3. Each student in chemistry requires 3 beakers in her lab drawer. How many beakers are required for a class of 7 students?

5

IV. SI Units of Measurement The SI system is an internationally accepted system of measurement. SI stands for the French “System International”. It encompasses the metric system as well as specific base units. It is necessary for a chemistry student to know the base units of the SI system. QUANTITY MEASURED SI UNIT SI SYMBOL Length Meter m Mass Kilogram kg Amount Mole mol Temperature Kelvin K (not oK) Time Second s Volume Cubic meter (informally, liter) m3 Pressure Pascal Pa Density Grams per cm3 or grams per mL g/cm3 or g/mL Whenever these SI units are used, metric prefixes are also used. These should be memorized as well. These prefixes allow for using much larger and much smaller multiples of the base units. For example, a megameter would be 1 x 106 meters. A kilogram = 1 x 103 grams. A centimeter = 1 x 10-2 meters. A micromole = 1 x 10-6 moles. PREFIX SYMBOL MEANING Mega M X 106 (a million times larger) Kilo k X 103 (a thousand times larger) Deci da X 10-1 (ten times smaller) Centi c X 10-2 (a hundred times smaller) Milli m X 10-3 (a thousand times smaller Micro µ X 10-6 (a million times smaller) Nano n X 10-9 (a billion times smaller) Pico p X 10-12(a trillion times smaller) It is possible to convert between units by using dimensional analysis. Example: How many kilograms are present in 5000 grams? 5000 grams · 1 kilogram (kg) = 5 kg 1x 103g (1000 g) Example: How many nanograms are present in 20 g? 20 g · 1 x 109 ng = 20,000,000,000 ng 1 g Questions: How many grams are present in 29 kg? How many millimeters are present in 2 meters?

6

V. Scientific Notation In chemistry we use very large and very small numbers to represent amounts and masses. In order to effectively communicate these numbers without using lots of zeros, we employ scientific notation. Each value is written as the product of two numbers, one of which is a power of 10. The first number is always a single digit number, which may or may not have any number of decimal places. Numbers which are greater than 1 have a positive exponent. Numbers which are less than 1 have a negative exponent. For example: Converting to scientific notation: 36,000 would be written as 3.6 x 104 23.67 would be written as 2.367 x 101 35069032 would be written as 3.5068032 x 107

0.003 would be written as 3 x 10-3 0.23999 would be written as 2.3999 x 10-1

0.000000000000000000000007 would be written as 7 x 10-24 Converting from scientific notation to equivalent decimal numbers: 3.55 x 103 would be written as 3550 6.887 x 10-6 would be written as 0.000006887 Questions: Convert the following in scientific notation: 45 ____________________ 699 _____________________ 2884 ______________________ 28395____________________ 0.344_________________ 45.83 _____________________ 302.555___________________ 0.00043502 ______________________ Convert the following from scientific notation to their equivalent decimal numbers: 3.692 x 106 ________________ 4.9 x 10-2___________________ 1.9734 x 105 __________________ 5.55050 x 10-9 __________________ 7 x 10-3__________________ 9.97 x 10-1_________________

VI. Accuracy and Precision

7

It is impossible for measurements to be perfect. Many sources of error can exist when humans take measurements. All measurements have some amount of uncertainty. Good precision concerning measurements entails making a series of measurements. Precision is increased with additional measurements. It is also increased with an increased number of decimal places in the measurement. If I were to use two scales to weigh an object, and one scale weighed to the 0.00 place, and the second to the 0.0000 place, I would get more precise measurements with the scale that measured to the 0.0000 place (providing the level of accuracy in both was equal- see below). If we were to take many measurements of the same object, and the values obtained were very similar, We could state that our measurements were PRECISE. That is, they agreed closely with one another. If I were weighing a marshmallow on a scale that measured to the hundredth’s place and obtained three values of 1.00 g, 1.01 g, and 0.99 g, I could state that I had good precision. My three measurements were close to one another. These measurements were PRECISE. Precision can only be determined if a SERIES of measurements are taken. Good precision would require that the measurements be close in value to one another. Does that mean that they were also ACCURATE? Not necessarily. ACCURACY is defined as how close the measurements are to the true value. If the true mass of our marshmallow was indeed 1.00 g, then our measurements were accurate and precise. If, however, the true mass of our marshmallow was 1.50 g, then our measurements were precise, that is, they agreed with one another, but not accurate, as they were far from the true value, which was 1.50 g. In order to determine accuracy, the true measurement must be known. Questions: 1. Three measurements are made of the mass of a new automobile. The first is 3500 lbs., the second is 3502 lbs., and the third is 3501 lbs. The actual mass is known to be 3500 lbs. Are these measurements of mass accurate? ___________ Are they precise?_____________ 2. I buy a 2 x 4 board from Home Depot. I measure it with an extremely fine measuring tool and find the width of the board to be 4 inches. Can I say that the board was accurately measured by Home Depot? _______________ Can I say that my measurement = 4 inches was precise?______________ 3. In question # 2, how would it be possible to increase the precision of my measurement? __________________________________________________________________________________ 4. I have a choice of two scales to use to weigh myself. The first will weigh in pounds, the second scale in pounds with marks between each to indicate the ½ pound weight. Which will be more precise if both are accurate?

8

VII. Significant Figures In chemistry the concept of significant figures is always used when discussing or doing calculations with measured amounts. Significant figures apply ONLY to measured quantities. The principle behind significant figures is this: if I am measuring any quantity, my measurement will consist of all the digits I am sure of, and the last digit, which is a reasonable estimate. Example: I use the grocery store scale to weigh my fruit. The scale has divisions of pounds, with 10 divisions between each pound to indicate tenths of pounds. So if I put my apples on the scale and it reads 3.5 pounds and the arrow is not exactly on the 5, but it appears to be exactly between 3.5 and 3.6 pounds, I can estimate that I have 3.55 pounds of apples. I am sure I have 3.5 pounds, and I think I have 3.55 pounds, but the last 5 is really an estimate. I am sure of the 3.5, and reasonably sure of the 3.55, but that last 5 is not certain. SO: significant figures include all digits we are sure of PLUS the last one, which is a very good estimate. Questions: Which digit of the following measurements is NOT significant, but a very good estimate? 2.379 inches ___________ 19.334 m ____________ 890.5 miles_______________ In addition, there are rules that determine whether digits are significant or not. Below are the Rules: 1. All non-zero digits and zeros BETWEEN non-zero digits, are significant. Example: 245 has 3 significant figures (sig figs) 2405 has 4 sig figs. 2. Zeros at the END of a number and to the right of a decimal point ARE always significant. Example: 23.0 has 3 sig figs. 23.00 has 4 sig figs. 23.000 has 5 sig figs. 3. Zeros appearing to the left of all non-zero digits are NOT significant if they just act as place holders. Example: 0.0071 has 2 sig figs (the 7 and 1) The three zeros to the left of the 71 are Not significant because they are merely place holders. 4. Zeros appearing to the right of non-zero digits where NO DECIMAL POINT is present are NOT significant. These are merely placeholders. Example 7100 has 2 sig figs, the 7 and the 1. The two zeros are merely placeholders. There is no decimal point. [If the number had been written as 7100., there would be 4 sig figs because the decimal point appearing after the 7100. makes the two zeros significant.] 5. In two cases, there are an unlimited number of sig figs., i.e, they cannot be quantified. These two cases are a) when objects are counted (you cannot have 5.3 toes on your left foot) and b) when numbers are used as conversion factors, i.e.; 12 inches/ 1 ft. Here sig figs do not enter the equation.

9

VIII. Using Significant Figures in Calculations When making measurements, and using those measurements in a calculation, the result of the calculation can NEVER have more accuracy than the measurement with the least amount of accuracy. So, in order to obey this rule of Sig Figs, it is necessary to define how we will do calculations. ADDITION OR SUBTRACTION If the calculation involves addition or subtraction, the answer can have no more decimal places than the measurement with the LEAST number of decimal places. Example: 12.1 inches + 2.1 inches + 3.03 inches = According to our calculator, the answer to this question is 17.23 inches. BUT: using sig fig rules we would give the answer as ~ 17.2 inches. Yes, the calculator says 17.23 inches, but sig fig rules say we can only have an answer with ONE DECIMAL PLACE, because our least precise measurements, the 2.1 and 12.1 inch measurements only have one decimal place. OUR ANSWER CAN ONLY HAVE ONE DECIMAL PLACE if we are ADDING OR SUBTRACTING. Do all the calculations on the calculator, then ROUND for significant figures. If adding or subtracting, put all the digits in the calculator, obtain an answer, then round off to the correct number of sig figs. Questions: Do the following calculations and round for significant figures: a) 8.7 g + 15.43 g + 19 g = b) 853.2 L – 642.333 L = MULTIPLICATION OR DIVISION When multiplying or dividing, and using sig figs, the final answer can have only as many sig figs as the measurement with the LEAST number of sig figs. Example: 6.3 cm x 2.2 cm = 13.86 cm2 according to my calculator. Using sig figs, my answer would be ~ 14. I must round my answer to 2 sig figs because each measurement in the problem, the 6.3 and 2.2 cm, each only have 2 sig figs. Example: 6.66 cm / 3.2 cm = 2.08125 cm2 according to my calculator. Using sig figs, my answer is rounded to 2.1. The measurement in the problem with the least number of sig figs is the 3.2 cm. Thus, my answer cannot have more than 2 sig figs, because 3.2 has 2 sig figs. Questions: Do the following calculations and round for significant figures: a) 4.32 cm x 1.7 cm = c) 5.40 m x 3.21 m x 1.871 m = b) 38.742 kg ÷ 0.421 kg = d) 38.0 in ÷ 2.121 in =

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IX. Qualitative and Quantitative Measurements Qualitative measurements are descriptive – “It is really cold today.” This sentence describes the temperature without stating an exact temperature. Quantitative measurements are specific – “It is 10 degrees below zero today.” This sentence tells us exactly how cold it really is. It quantifies, or gives an exact quantity, to the temperature. Both qualitative and quantitative measurements have value. Questions: Give an example of a qualitative measurement you might make in everyday life. Give an example of a quantitative measurement that you might make in everyday life. X. Temperature Conversions Temperature measurements are important in chemistry. We will employ two temperatures scales, the Celsius and Kelvin scales. Conversion between the two is much simpler than any Fahrenheit conversions you have learned in other science classes. Forget Fahrenheit. It is not used in chemistry. The Celsius scale is named after the Swedish astronomer Anders Celsius. Water freezes at 0oC, and water boils at 100oC. Easy to remember and IMPORTANT. Room temperature is between 20oC and 25oC, and body temperature is 37oC. The Kelvin scale is named after Lord Kelvin, and is designated as just Kelvins. Not degrees Kelvin. Kelvin degrees are the same size as Celsius degrees, so that an increase of 1oC is the same magnitude of temperature increase as an increase of 1 K. 0oC = 273 K SO water freezes at 273 K 100oC = 373 K SO water boils at 373 K To convert from Celsius to Kelvin, simply add 273 to the Celsius temperature. To convert from Kelvin to Celsius, simply subtract 273 from the Kelvin temperature. Example: 10oC = 283 K 298 K = 25oC. Questions: Do the following conversions: 4 K = ______oC 170oC = _______K 87 K = ______oC 222oC = ___________ K