Is the study of matter, its properties, the changes that matter undergoes, and

CHEMISTRY Is the study of matter, its properties, the changes that matter undergoes, and the energy associated with these changes. 1-

Matter anything that has mass and volume -the “stuff” of the universe: books, planets, trees, teachers, students Properties the characteristics that give each substance a unique identity Definitions Physical Properties those which the substance shows by itself without interacting with another substance such as color, melting point, boiling point, density Chemical Properties those which the substance shows as it interacts with, or transforms into, other substances such as flammability, corrosiveness 1-

Physical change A substance alters its physical form, not its composition Chemical change A substance is converted into a different substance Figure 1.1 The distinction between physical and chemical change. 1-

Table 1.1 Some Characteristic Properties of Copper Physical Properties Chemical Properties slowly forms a basic blue-green sulfate in moist air reddish brown, metallic luster easily shaped into sheets (malleable) and wires (ductile) reacts with nitric acid and sulfuric acid good conductor of heat and electricity density = 8.95 g/cm3 slowly form a deep-blue solution in aqueous ammonia melting point = 10830C boiling point = 25700C 1-

Figure 1.2 The physical states of matter. 1-

PROBLEM: Decide whether each of the following process is primarily a physical or a chemical change, and explain briefly: Sample Problem 1.1 Distinguishing Between Physical and Chemical Change (a) Frost forms as the temperature drops on a humid winter night. (b) A cornstalk grows from a seed that is watered and fertilized. (c) Dynamite explodes to form a mixture of gases. (d) Perspiration evaporates when you relax after jogging. (e) A silver fork tarnishes slowly in air. SOLUTION: (a) physical change (b) chemical change (c) chemical change (d) physical change (e) chemical change 1-

Energy is the capacity to do work. Potential Energy energy due to the position of the object or energy from a chemical reaction Kinetic Energy energy due to the motion of the object Potential and kinetic energy can be interconverted. 1-

Energyis the capacity to do work. Figure 1.3B less stable change in potential energyEQUALS kinetic energy more stable A system of two balls attached by a spring. The potential energy gained by a stretched spring is converted to kinetic energy when the moving balls are released. 1-

Energy is the capacity to do work. Figure 1.3C less stable change in potential energyEQUALS kinetic energy more stable A system of oppositely charged particles. The potential energy gained when the charges are separated is converted to kinetic energy as the attraction pulls these charges together. 1-

Hypothesis: Tentative proposal that explains observations. revised if experiments do not support it Procedure to test hypothesis; measures one variable at a time. Experiment: Set of conceptual assumptions that explains data from accumulated experiments; predicts related phenomena. Theory(Model): altered if predictions do not support it Further Experiment: Tests predictions based on model. Scientific Approach: Developing a Model Observations : Natural phenomena and measured events; universally consistent ones can be stated as a natural law. 1-

Alchemist at Work 1-

Lavoisier(1743 – 1794) • Debunked phlogiston theory • Demonstrated the true nature of combustion • Named oxygen 1-

A Systematic Approach to Solving Chemistry Problems • Problem statement Clarify the known and unknown. • Plan Suggest steps from known to unknown. Prepare a visual summary of steps. • Solution • Check Comment and Follow-up Problem 1-

PROBLEM: To wire your stereo equipment, you need 325 centimeters (cm) of speaker wire that sells for $0.15/ft. What is the price of the wire? Sample Problem 1.2 Converting Units of Length PLAN: Known - length (in cm) of wire and cost per length ($/ft) We have to convert cm to inches and inches to ft followed by finding the cost for the length in ft. length (cm) of wire Follow up Problem 1.2 A furniture factory needs 31.5 ft2 of fabric to upholster one chair. The supplier sends the fbric in bolts of exactly 200 m2. What is the maximum number of chairs that can be upholstered by 3 bolts of fabric? 1 m = 3.281 ft length (in) of wire 2.54 cm = 1 in length (ft) of wire 12 in = 1 ft Price ($) of wire 1 ft = $0.15 1-

SI Base Units Table 1. 2 time second s temperature kelvin K electric current ampere A amount of substance mole mol luminous intensity candela cd Physical Quantity (Dimension) Unit Abbreviation Unit Name mass kilogram kg length meter m 1-

Table 1.3 Common Decimal Prefixes Used with SI Units 1-

Densities of Some Common Substances* Table 1.5 Hydrogen Gas 0.0000899 Oxygen Gas 0.00133 Grain alcohol Liquid 0. 789 Water Liquid 0.998 Table salt Solid 2.16 Aluminum Solid 2.70 Lead Solid 11.3 Gold Solid 19.3 Substance Physical State Density (g/cm3) *At room temperature(200C) and normal atmospheric pressure(1atm). 1-

Sample Problem 1.5 Calculating Density from Mass and Length PROBLEM: Lithium (Li) is a soft, gray solid that has the lowest density of 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 ? 1-

The freezing and boiling points of water. Figure 1.12 1-

Temperature Scales and Interconversions Kelvin ( K ) - The “Absolute temperature scale” begins at absolute zero 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 - 273.15 oF = (9/5) oC + 32 oC = [oF - 32 ] 5/9 1-

Sample Problem 1.6 Converting Units of Temperature A 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 child’s temperature in Kelvin? 1-

Figure 1.14 The number of significant figures in a measurement depends upon the measuring device. 32.33 oC 32.3 oC 1-

Rules for Determining Which Digits are Significant Leading zeros are not significant. • If the measured quantity has a decimal point start at the left of the number and move right until you reach the first nonzero digit. • Count that digit and every digit to it’s right as significant. Zeros that end a number and lie either after or before the decimal point are significant; thus 1.030 ml has four significant figures, and 5300. L has four significant figures also. Numbers such as 5300 L are assumed to only have 2 significant figures. A terminal decimal point (or a bar) is often used to clarify the situation, but scientific notation is the best! • If the measured quantity does not have a decimal point start at the right of the number and move leftt until you reach the first nonzero digit. • Count that digit and every digit to it’s left as significant. 1-

(a)2sf (b) 4sf (c) 5sf (d)4sf (e) 5sf (f) 4sf Sample Problem 1.7 Determining the Number of Significant Figures For each of the following quantities, determine the number of significant figures in each quantity. (a) 0.0030 L (b) 0.1044 g (c) 53,069 mL (d) 0.00004715 m (e) 57,600. s (f) 0.0000007160 cm3 SOLUTION: 1-

Rules for Rounding Off Numbers 1. If the digit removed is more than 5, the preceding number increases by 1. 5.379 rounds to 5.38 if three significant figures are retained and to 5.4 if two significant figures are retained. 2. If the digit removed is less than 5, the preceding number is unchanged. 0.2413 rounds to 0.241 if three significant figures are retained and to 0.24 if two significant figures are retained. 3.If the digit removedis 5, the preceding number increases by 1 if it is odd and remains unchanged if it is even. 17.75 rounds to 17.8, but 17.65 rounds to 17.6. If the 5 is followed only by zeros, rule 3 is followed; if the 5 is followed by nonzeros, rule 1 is followed: 17.6500 rounds to 17.6, but 17.6513 rounds to 17.7 4. Be sure to carry two or more additional significant figures through a multistep calculation and round off only the finalanswer. 1-

Precision and Accuracy Errors in Scientific Measurements Precision - Refers to reproducibility orhow close the measurements are to each other. Accuracy - Refers to how close a measurement is to the real value. Systematic error - Values that are either all higher or all lower than the actual value. Random Error - In the absence of systematic error, some values that are higher and some that are lower than the actual value. 1-

precise and accurate precise but not accurate Figure 1.16 Precision and accuracy in the laboratory. 1-

random error systematic error Precision and accuracy in the laboratory. Figure 1.16 continued 1-

Is the study of matter, its properties, the changes that matter undergoes, and