CHEMISTRY - MCQUARRIE 4E CH.1 - CHEMISTRY & THE SCIENTIFIC METHOD.

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2 CONCEPT: MATTER Chemistry is the study of matter and the changes it undergoes, with the being its basic functional unit. When two or more of these elements chemically bond together they form an independent structure called a molecule. Classification of Matter Under appropriate conditions of pressure and temperature, most substances can exist in 3 states of matter:, and. have a fixed shape and volume. take up the shape and volume of a container. conform to the shape of a container, but not the volume. Microscopic Explanation for the Behavior of Gases, Liquids and Solids Gas Liquid Solid Assumes the and of its container. Assumes the of the portion of its container it occupies, but not the. Maintains a fixed and compressible compressible compressible Viscosity Viscosity Viscosity Viscous Viscous Viscous Page 2

3 CONCEPT: SCIENTIFIC NOTATION We use scientific notation to turn small or large, inconvenient numbers into manageable ones x The first number 6.88 is called the. It must be greater than or equal to 1 and less than 10. The second number is known as the. It must always be 10 in scientific notation. In the number 6.88 x 10-12, the number -12 is referred to as the. EXAMPLE 1: Convert the following numbers into scientific notation a. 377,000 b c d x 10 7 e x 10-9 Page 3

4 CONCEPT: ERROR Even though we try to be as accurate as possible, there is always some level of uncertainty called. When we investigate the quality of an experimental decision or calculation we take into account two major principles: deals with the reproducibility of our calculations. deals with how close our measured calculation is to the actual value. EXAMPLE 1: Which of the 4 following images is not precise and not accurate? PRACTICE: A student must measure the weight of a sodium bicarbonate compound, NaHCO3, and obtains the following measurements: g, g and 23.17g. If the true weight of the compound is g what can be said about the student s results? a. They are accurate and precise. b. They are accurate, but not precise. c. They are neither accurate or precise. d. They are not accurate, but precise. Page 4

5 CONCEPT: EVALUATING YOUR MEAN VALUE The measures how close data results are in relation to the mean, or average, value. To check if the results are close to the true value we can merely look, but sometimes determining their accuracy may require more work. Σ(x 1 x) 2 n 1 x = x = n = Page 5

6 CONCEPT: METRIC PREFIXES pico nano micro milli centi deci 0 deca hecto kilo mega giga tera (p) (n) (µ) (m) (c) (d) (da) (h) (k) (M) (G) (T) Page 6

7 CONCEPT: SIGNIFICANT FIGURES Significant figures are necessary to communicate the level of accuracy with which values are recorded. It can be easy if you remember these 2 rules. 1. If your number has a decimal point move from. o Start counting once you get to your first non-zero number and keep counting until you get to the end. 2. If your number has NO decimal point move from. o Start counting once you get to your first non-zero number and keep counting until you get to the end. EXAMPLE 1: How many sig figs does each number contain? (1) m (2) 749 mol (3) 17.3 x 10 3 ml (4) 100. min (5) kg (6) 1560 mol EXAMPLE 2: Read the length of the metal bar to the correct number of significant figures. a) 15 cm b) cm c) 20 cm d) 15.0 cm e) cm Page 7

8 CONCEPT: CALCULATIONS & SIGNIFICANT FIGURES Multiplication/Division: Measurement with least determines final answer. Addition/Subtraction: Measurement with least determines final answer. EXAMPLE 1: Perform the following calculation to the right number of sig figs: (3.16) x ( ) x (5.7 x 10-3 ) EXAMPLE 2: Perform the following calculation to the right number of sig figs: x x x 10 7 EXAMPLE 3: Perform the following calculation to the right number of sig figs: ( ) ( ) ( ) + ( ) Page 8

9 CONCEPT: TEMPERATURE Temperature is a measure of thermal energy in a substance, which is on the amount of matter. This is an example of property.,,,,. Heat is a form of thermal energy, which is on the amount of matter. This is an example of property.,,. EXAMPLE 1: Which of the following has the greatest amount of heat? 30 g H 2 O at 50 o C 300 g H 2 O at 50 o C 30 g H 2 O at 100 o C Temperature Conversions Temperature conversions are easy, as long as you know how to solve for x. You only need to know 2 equations to convert from the 3 different units of temperature: K = o C o F = 1.8 ( o C) + 32 EXAMPLE 2: Convert the following units of temperature a C into Fahrenheit b K into Fahrenheit Page 9

10 CONCEPT: MIXTURES Most matter consists of mixtures of pure substances. mixtures have no distinguishable parts. mixtures have some distinguishable parts. Changes of Matter changes are changes in the form of the substance, but not in its chemical composition. changes create new substances with different properties and different chemical compositions. EXAMPLE 1: Which of the following represents a physical change? a. Alkanes burn spontaneously. b. The sublimation of CO2. c. 2 H2 (g) + O2 (g) 2 H2O (g) d. The rusting of a car. Page 10

11 CONCEPT: CONVERSIONS Length 1 km = miles 1 m = yards 1 in = 2.54 cm 1 mile = 5280 ft Volume 1 gallon = L 1 L = dm 3 1 ml = 1 cm 3 1 L = qt Mass 1 kg = lbs 1 lb = 454 g 1 oz = g EXAMPLE 1: Every Saturday morning Gregor has to travel from Main Campus to his parents home. If his car gets 58.5 km/l how many L will his car need to travel the 19.3 miles? EXAMPLE 2: A backyard swimming pool holds 315 cubic yards (yd 3 ) of water. What is the mass of the water in pounds? PRACTICE: An intravenous bag delivers medication to a patient at a rate of 2.75 drops a second. If a drop weighs 42 mg, how many grams of solution are delivered in 7.0 hours? Page 11

12 CONCEPT: DIMENSIONAL ANALYSIS We use dimensional analysis as a fail proof process to convert from one unit to another. - Design the problems to with your known, and to with the unit of your unknown. - Be sure ALL of your units cancel out! Just follow the units. EXAMPLE 1: Natty Light contains 4.2% alcohol. Steve from Kappa Epsilon Gamma, KEG for short, wants to get tanked tonight, and he is aiming to down at least 175 ml of alcohol in one night. If each can of Natty light contains 355 ml of beer, how many cans of Natty Light must Steve consume at minimum to reach his goal? EXAMPLE 2: A Volkswagen diesel engine consumes diesel at a rate of L per hour. If the density of the diesel is g/ml, what is the mass (in mg) of diesel needed to drive for a continuous 8.5 hours? PRACTICE: An acetaminophen suspension for toddlers contains 95 mg/0.85 ml suspension. The recommended dose is 22 mg/kg body weight. How many liters of this suspension should be given to a toddler weighing 30.5 lbs? Page 12

13 CONCEPT: DENSITY We use density to understand the relationship between and. We can use it within dimensional analysis to go from one unit to the other or vice versa. Density = EXAMPLE 1: If the density of an unknown metal is 21.4 g/cm 3, express its density in lb/ft 3. Remember that 1 in = 2.54 cm. EXAMPLE 2: A piece of unknown metal weighs approximately 0.45 lbs. When a scientist places it in a glass beaker the water level increases from 1.85 L to 2.13 L. What is the density of the palladium metal in g/ml? PRACTICE: The U.S. Environmental Protection Agency sets the maximum safe level of lead in blood at 24 µg per dl of blood. The average person has 60 ml of blood per kilogram of body weight. For a 63.7-kg ( lb) person, what is the total maximum safe content of lead in blood? Page 13

14 6. Determine the best possible answer(s) for each of the following questions based on the periodic table. Which of the following statements is/are true? a) Phosphorus is a homonuclear diatomic molecule. b) Zinc is a Type I Metal c) Tin is a Type II metal. d) Europium (Eu) is an actinide metal Which nonmetal exists as a diatomic liquid at room temperature? Bromine Tellurium Sulfur Chlorine Iodine Page 14

15 8. The barium content of a metal ore was analyzed several times by a percent composition process. Method Barium (weight %) a) Calculate the mean, median and mode. b) Calculate the standard deviation. Page 15

16 13. Determine which of the following represents a physical change and a chemical change. a) b) c) Page 16

17 14. Answer each of the following questions based on the images provided below. a) Which of the following images represents an elemental gas? b) Which of the following images represents a heterogeneous mixture? c) Which of the following images represents a liquid? Page 17

18 15. Which of the following represents a physical property? a) Mercury is a liquid at room temperature. b) Alkanes burn spontaneously. c) CO2 (s) CO2 (g) d) 2 H2 (g) + O2 (g) 2 H2O (g) e) The rusting of a car. Page 18

19 18. A cigarette lighter contains the substance butane, C4H10, with the given properties. a) The lighter contains 10 g of butane b) the density of butane is 0.57 g/cm 3 c) The freezing point of the butane is -138 o C d) Butane is combustible in air. Which of the following features is a chemical change? Which of the following properties are intensive properties? Page 19

20 19. Which of the following properties about an unknown metal represent chemical properties? I. It has a bluish-green color. II. Upon exposure to air the metal experiences corrosion. III. It has a density of 4.36 g/cm 3. IV. It has a boiling point of 522 o C. V. It conducts electricity. a. IV b. V c. I, II, III d. II e. IV and V Page 20

21 25. An empty flask has a volume of 250 ml. When water is placed inside the flask (d = g/ml) the volume is ml. What is the mass (in grams) of the water inside the flask? Page 21

22 26. If a statue at an art gallery is covered in 279 kg of copper. If the copper on the statue has a thickness of cm, what surface area is covered (in square meters)? Copper has a density of 8.96 g/cm 3. Page 22

23 30. A Volkswagen diesel engine consumes diesel at a rate of L per hour. If the density of the diesel is g/ml. What is the mass (in mg) of diesel needed to drive for a continuous 4.3 hours? Page 23

24 32. If the charge and mass of one proton is x C and x g respectively, what is the charge of 378 kg of protons. Page 24

25 32. A cylindrical tube has a length that is 15.2 cm and is filled with bromine liquid. If the mass of the bromine is g and has a density of 25.3 g/ml. What is the inner diameter of the glass tube? ( V = π r 2 h ) Page 25

26 33. A large body of water contaminated with lead has an average depth of 750 m, a total area of 1.25 x 10 5 km 2, and an average of 5.8 x g/l of dissolved lead. How many milligrams of lead are in this large body of water? Page 26

27 34. Calculate the mass (in grams) of a golden sphere with a diameter of 30.0 mm. The density of gold is 19.3 g/cm 3. (Vsphere = π! r 3 ). Page 27