Chapter 1 Introduction: Matter and Measurement

Chemistry: The study of matter and the changes it undergoes.

Scientific Method: A systematic approach to solving problems.

Matter: Anything that has mass and takes up space.

Matter Atoms are the building blocks of matter.

Matter Atoms are the building blocks of matter. Each element is made of the same kind of atom.

Matter Atoms are the building blocks of matter. Each element is made of the same kind of atom. A compound is made of two or more different kinds of elements.

States of Matter

Classification of Matter

Classification of Matter

Classification of Matter

Classification of Matter

Classification of Matter

Classification of Matter

Classification of Matter

Classification of Matter

Classification of Matter

Classification of Matter

Mixtures and Compounds

Properties and Changes of Matter

Properties of Matter Physical Properties: Chemical Properties: Can be observed without changing a substance into another substance. Boiling point, density, mass, volume, etc. Chemical Properties: Can only be observed when a substance is changed into another substance. Flammability, corrosiveness, reactivity with acid, etc.

Properties of Matter Intensive Properties: Extensive Properties: Independent of the amount of the substance that is present. Density, boiling point, color, etc. Extensive Properties: Dependent upon the amount of the substance present. Mass, volume, energy, etc.

Changes of Matter Physical Changes: Chemical Changes: Changes in matter that do not change the composition of a substance. Changes of state, temperature, volume, etc. Chemical Changes: Changes that result in new substances. Combustion, oxidation, decomposition, etc.

Chemical Reactions In the course of a chemical reaction, the reacting substances are converted to new substances.

Chemical Reactions

Compounds Compounds can be broken down into more elemental particles.

Electrolysis of Water

Separation of Mixtures

Distillation: Separates homogeneous mixture on the basis of differences in boiling point.

Distillation

Filtration: Separates solid substances from liquids and solutions.

Chromatography: Separates substances on the basis of differences in solubility in a solvent.

Units of Measurement

SI Units Système International d’Unités Uses a different base unit for each quantity

Metric System Prefixes convert the base units into units that are appropriate for the item being measured.

Volume The most commonly used metric units for volume are the liter (L) and the milliliter (mL). A liter is a cube 1 dm long on each side. A milliliter is a cube 1 cm long on each side.

Uncertainty in Measurements Different measuring devices have different uses and different degrees of accuracy.

Temperature: A measure of the average kinetic energy of the particles in a sample.

Temperature In scientific measurements, the Celsius and Kelvin scales are most often used. The Celsius scale is based on the properties of water. 0C is the freezing point of water. 100C is the boiling point of water.

Temperature The Kelvin is the SI unit of temperature. It is based on the properties of gases. There are no negative Kelvin temperatures. K = C + 273.15

Temperature The Fahrenheit scale is not used in scientific measurements. F = 9/5(C) + 32 C = 5/9(F − 32)

Physical property of a substance Density: Physical property of a substance d= m V

Uncertainty in Measurement

Significant Figures The term significant figures refers to digits that were measured. When rounding calculated numbers, we pay attention to significant figures so we do not overstate the accuracy of our answers.

Significant Figures All nonzero digits are significant. Zeroes between two significant figures are themselves significant. Zeroes at the beginning of a number are never significant. Zeroes at the end of a number are significant if a decimal point is written in the number.

Significant Figures When addition or subtraction is performed, answers are rounded to the least significant decimal place. When multiplication or division is performed, answers are rounded to the number of digits that corresponds to the least number of significant figures in any of the numbers used in the calculation.

Accuracy versus Precision Accuracy refers to the proximity of a measurement to the true value of a quantity. Precision refers to the proximity of several measurements to each other.

Review Learned Skills Define accuracy Define precision Operations with Scientific Notation Significant digits

Review Learned Skills Accuracy – how close to the actual true value you are. Precision – how close your measurements are to each other.

Review Learned Skills Operations with Scientific Notation Addition (exponents must be the same) Subtraction (exponents must be the same) Multiplication (add exponents) Division (subtract exponents)

Review Learned Skills Significant digits 123.5 ( four significant digits) 12,00.05 (six significant digits) 0.0012 (2 significant digits) 14,000 (2 significant digits) 6.022 x 1023 (four significant digits)

Review Learned Skills Significant digits in calculations In multiplication and division the answer must contain the fewest significant figures. Example 4.38 meters x 3.1 meters = 13.578 or 14 m2 2.85 cm x 7.2 cm = 20.52 or 21 cm2

Review Learned Skills Significant digits in calculations In addition and subtraction the result must have the same number of decimal places as the one with the fewest decimal places. Example 4.38 meters + 3.1 meters = 7.48 or 7.5 m 2.85 cm + 7.2 cm = 10.05 or 10.1 cm

Dimensional Analysis Method of managing multiple levels of conversion Used to organize solutions to chemistry problems

Compound Calculations Utilize derived formulas to determine the resulting calculations. Utilize dimensional analysis to determine the appropriate units

Compound Calculations Example What is the area of a rectangular that is 10.3m long and 3.7m wide. Provide the answer in cm2. Area = length x width

Dimensional Analysis What is the area of a rectangular that is 10.3m long and 3.7m wide. Provide the answer in cm2. 10.3m 3.7 m 100cm2 1 1 1 m2

Dimensional Analysis 10.3m 3.7 m 100 cm2 3.81 x 103 cm2 1 1 1 m2

Dimensional Analysis Practice Example What is the average speed of an object that travels 1856 meters in 900 seconds. Provide the answer in Kilometers. Average speed = distance / time

Dimensional Analysis What is the average speed of an object that travels 1856 meters in 900 seconds. Provide the answer in Kilometers. 1856 m 1 Km 900 s 1000 m

Dimensional Analysis 1856 m 1 Km 1856 Km 900 s 1000 m 900,000 s 2.06 x 10-3 Km/s

Dimensional Analysis Practice Example What is the average acceleration of an object that travels 956 meters in 200 seconds. Provide the answer in Kilometers. Average speed = distance / time Acceleration = Average speed / time

Dimensional Analysis Practice What is the average acceleration of an object that travels 956 meters in 200 seconds. Provide the answer in Kilometers. 956 m 1 1 Km 200 s 200s 1000 m

Dimensional Analysis Practice 956 m 1 1 Km 2.39 x 10-5 Km/s2 200 s 200s 1000 m

Complex Compound Calculations Example Using the ideal gas law what is the pressure in Torr of 2 moles of gas at 298 K that fills a container totaling 1.5 L. PV = NRT P (atm) V (liters) = N R (L atm/mol K) T (Kelvin)

Dimensional Analysis Using the ideal gas law what is the pressure in Torr of 2 moles of gas at 298 K that fills a container totaling 1.5 L. 2.0 mol 0.0821 L atm 298 K 760 torr 1.5 L 1 mol K 1 1 P = NRT V

Dimensional Analysis 2.47 x 104 Torr 2.0 mol 0.0821 L atm 298 K 760 torr 37,188.0 16 torr 1.5 L 1 mol K 1 1 atm 1.5 2.47 x 104 Torr

Complex Compound Calculations Practice Example Using the ideal gas law what is the volume in milliliters of 3 moles of gas at 200 K at a pressure of 3 atmospheres. PV = NRT P (atm) V (liters) = N R (L atm/mol K) T (Kelvin)

Dimensional Analysis Practice Using the ideal gas law what is the volume in milliliters of 3 moles of gas at 200 K at a pressure of 3 atmospheres 3.0 mol 0.0821 L atm 200 K 1000 ml 3 atm 1 mol K 1 1 L

Dimensional Analysis Practice 3.0 mol 0.0821 L atm 200 K 1000 ml 3 atm 1 mol K 1 1 L 1.64 x 104 ml

Complex Compound Calculations Group work Example A specific type of ore contains 10 grams of gold per 1000 kg. of ore. If gold is worth $400 an ounce, what mass of ore must be mined to obtain $ 1,000,000? (28.35 grams = 1 ounce)

Dimensional Analysis Practice A specific type of ore contains 10 grams of gold per 1000 kg. of ore. If gold is worth $400 an ounce, what mass of ore must be mined to obtain $ 1,000,000? (28.35 grams = 1 ounce) $1 x 106 1 oz AU 28.35 g 1000 kg ore 1 $ 400 1 oz 10g AU

Dimensional Analysis Practice A specific type of ore contains 10 grams of gold per 1000 kg. of ore. If gold is worth $400 an ounce, what mass of ore must be mined to obtain $ 1,000,000? (28.35 grams = 1 ounce) $1 x 106 1 oz AU 28.35 g 1000 kg ore 1 $ 400 1 oz 10g AU 7.09 x 106 kg ore