Chapter One Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry International University for Science & Technology College of Pharmacy General Chemistry (Students of Dentistry) Prof. Dr. M. H. Al-Samman

Chapter One Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry Chapter 1 Introduction: Matter & Measurement CHEMISTRY

Chapter One Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry - Chemistry is the study of the properties of materials and the changes that materials undergo. - Chemistry is central to our understanding of other sciences. - Chemistry is also encountered in everyday life. Why Study Chemistry

Chapter One Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry Chemistry: Catastrophe Prevention? The space shuttle Columbia disintegrated in 2003 upon reentry into the Earth’s atmosphere due to a damaged thermal protection system.

Chapter One Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry 5 Chemistry: Matter and Measurement

Chapter One Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry 6 Scientific Measurements SI is the International System of Units. In SI, there is a single base unit for each type of measurement.

Chapter One Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry 7 Scientific Measurements: SI Prefixes Prefixes are used to indicate powers of ten of common units that are much smaller or larger than the base unit. Although there are many prefixes, only a few are in very common use. In measurements, kilo-, centi-, and milli- are the three most common prefixes.

Chapter One Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry 8 1 in. ––––––– = cm Unit Conversion: Conversion Factors Example: 2.54 cm = 1 in. ––––––– = 1 1 in. We use these conversion factors to convert in. to cm and to convert cm to in. Multiply the quantity we are given by the appropriate factor. Question: Which factor is used for each task? Answer: Use the one that cancels the unit we do not need, and leaves the unit we want. We can write two conversion factors:

Chapter One Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry 9 Length 1m=10¹dm=10²cm=10³mm=10 ⁶ μ=10 ⁹ n=10¹²p 1m=10 ⁻ ¹da=10 ⁻ ²h=10 ⁻ ³km=10 ⁻⁶ M=10 ⁻⁹ G 1 in=2.54 cm 1 yard= cm 1 foot=30.48 cm 1 mile=176 yard= m Scientific Measurements

Chapter One Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry 10 Volume 1Lit=1000ml or 10 ³ ml =1000cm³ or 10 ³ cm³ 1ml=1cm³ 1 lit=1.057 qt 1 gallon = lit 1 fluid ounce (fl oz) = ml Mass 1kg=10³g=10 ⁶ mg=10 ⁹ ng=10 ¹² pic g 1kg=10 ⁻ ³ton 1lb=453.6 grams 1ounce (oz) =28.35 g Scientific Measurements

Chapter One Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry 11 Example : What is the length in millimeters of a 1.25-ft rod? Answer: 1 ft = cm = mm The length = 1.25 x = 381 mm Scientific Measurements

Chapter One Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry 12 Example: Convert the unit of each of the following measurements to a unit that replaces the power of ten by a prefix. (a) 9.56 × 10 –3 m (b) 1.07 × 10 3 g Answer: (a)=9.56 mm, (b)=1.07 kg Scientific Measurements

Chapter One Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry 13 Q- We have a cubic metallic sheet of alloy with dimensions 6 in edge and 4 in thick, in this sheet there is a vertical cylindrical hole with a 2 in diameter, if the density of the sheet is 8.79 g/cm ³, calculate the mass of the metallic sheet: 1- In grams 2- In ounces (oz). 3- In pounds (lb). EOS Scientific Measurements

Chapter One Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry 14 Precision and Accuracy in Measurements Precision – how closely repeated measurements approach one another. Accuracy – closeness of measurement to “true” (accepted) value. Darts are close together (precise) but they aren’t “bullseyes” (accurate). Darts are close together AND they are “bullseyes.”

Chapter One Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry 15 Uncertainty in Measurements Uncertainty in measurement: It is very important to realize that any measurement depends on the precision and accuracy of the devices. For example: In analyzing a sample of polluted water, the chemist measured out a ml of the water with a pipette, and in another experiment, the chemist 25 ml of the water using a graduated cylinder.( what is the difference in the two measurements). Even though the two measurements appear to be equal, but we can realize easily that the uncertainty in the first measurement is ∓ 0.01ml( between 25.01ml and 24.99ml), while that the uncertainty in the second experiment is ∓ 1 ml( between 24 ml and 26 ml).

Chapter One Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry 1.Nonzero integers always count as significant figures.  3456 has 4 sig figs (significant figures). Rules for Counting Significant Figures

Chapter One Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry There are three classes of zeros. a.Leading zeros are zeros that precede all the nonzero digits. These do not count as significant figures.  has 2 sig figs. (since we can write the value as 48x10 ⁻³). Rules for Counting Significant Figures

Chapter One Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry b.Captive zeros are zeros between nonzero digits. These always count as significant figures.  has 4 sig figs. Rules for Counting Significant Figures

Chapter One Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry c.Trailing zeros are zeros at the right end of the number. They are significant only if the number contains a decimal point.  has 4 sig figs.  150 has 2 sig figs.( since we can write this value as : 15x10 ⁺¹) Rules for Counting Significant Figures

Chapter One Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry 3.Exact numbers have an infinite number of significant figures.  1 inch = 2.54 cm, exactly.  9 pencils (obtained by counting). Rules for Counting Significant Figures

Chapter One Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry Example  can be written as 3.00 × 10 2  Contains three significant figures. Exponential Notation

Chapter One Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry Two Advantages of using the significant figures:  Number of significant figures can be easily indicated.  Fewer zeros are needed to write a very large or very small number. Exponential Notation

Chapter One Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry 1.For multiplication or division, the number of significant figures in the result is the same as the number in the least precise measurement used in the calculation × 5.5 =  7.4 Significant Figures in Mathematical Operations

Chapter One Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry 2.For addition or subtraction, the result has the same number of decimal places as the least precise measurement used in the calculation. Significant Figures in Mathematical Operations

Chapter One Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry Fahrenheit Celsius Kelvin Three Systems for Measuring Temperature

Chapter One Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry The Three Major Temperature Scales

Chapter One Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry 27 Temperature Temperature is the property that tells us the direction that heat will flow. The base unit of temperature is the kelvin (K). We often use the Celsius scale (°C) for scientific work. ٭On the Celsius scale, 0 °C is the freezing point of water, and 100 °C is the boiling point. The Fahrenheit scale (°F) is most commonly encountered in the U.S. ٭On the Fahrenheit scale, freezing and boiling water are 32 °F and 212 °F, respectively. T F = 1.8T C + 32 T C = (T F – 32)/1.8

Chapter One Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry 28 Example: How to relate the Fahrenheit scale Fº to the Celsius scale Cº? Answer: - Between the freezing point and the boiling point of pure distilled water, we write: 180 grade Fº ⇔ - Each 100 grade Cº - Each 1 grade Cº ⇔ x grade Fº x = 180/100 = 1.8 So, each grade Celsius is equal to 1.8 grade Fahrenheit. And since the freezing point of water in Fahrenheit scale is 32 degree, we write: T F = 1.8T C + 32 and T C = (T F - 32)/1.8 Temperature

Chapter One Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry 29 Example : Q-What is temperature degree in Fahrenheit scale which is equivalent to 16 Cº? Solution: T F = 1.8T C + 32 T F = (1.8x16 ) + 32 T F = 60.8 degree Temperature

Chapter One Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry 30 Example: At home you like to keep the thermostat at 72 °F. While traveling in Canada, you find the room thermostat calibrated in degrees Celsius. To what Celsius temperature would you need to set the thermostat to get the same temperature you enjoy at home? A- first let’s write the relations between Fahrenheight and Celsius scales T F = 1.8T C + 32 T C = (T F – 32)/1.8 T C = (72 – 32 )/1.8 T C = 22.2 ° C Temperature

Chapter One Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry 31 Density is the ratio of mass to volume: m d = ––– V Density can be used as a conversion factor. For example, the density of methanol is g/mL; therefore, there are two conversion factors, each equal to one: Density: A Physical Property and Conversion Factor g methanol –––––––––––––– and 1 mL methanol –––––––––––––– g methanol

Chapter One Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry 32 Example: A beaker has a mass of 85.2 g when empty and g when it contains 325 mL of liquid methanol. What is the density of the methanol? Answer: The mass of methanol: = g The density: d=257.2/325 = g/ml Density: A Physical Property and Conversion Factor

Chapter One Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry 33 Example: How many kilograms of methanol does it take to fill the gal fuel tank of an automobile modified to run on methanol? Answer: 1 gal = Lit The volume in Lit = 15.5 x = Lit d = g/ml = 0.791kg/Lit The mass of methanol = x = kg Density: A Physical Property and Conversion Factor

Chapter One Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry 34 Matter Matter: The matter is what occupies a size of space and has a mass. Matter can be divided into two types: - Substance Mixture -

Chapter One Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry 35 The Substance is divided into two types: - Elements such as copper and carbon - Compounds such as water and sodium hydroxide. Water molecule Matter

Chapter One Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry 36 Classifying Matter A substance: has a definite or fixed composition that does not vary from one sample to another. An element: It is a substance consists of the same atoms and cannot be broken down into other simpler substances by chemical reactions. A compound: It is made up of two or more elements in fixed proportions, and can be broken down into simpler substances. Carbon dioxide, sodium chloride, sucrose (sugar), etc.

Chapter One Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry 37 The Mixture is divided into two types: - Homogeneous Mixtures such as water- alcohol,Gold 21. -Heterogeneous Mixtures such as sand, oil-water, table, and computer. Classifying Matter

Chapter One Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry 38 Classifying Matter A mixture: does not have a fixed composition. A homogeneous mixture ( solution): has the same composition throughout the sample, but the composition of different homogeneous mixtures may vary. We call homogeneous mixtures; solutions ٭Soda pop, salt water, 14K gold, and oxygen in nitrogen in air are homogeneous mixtures. ٭10K gold and 14K gold have different compositions but both are homogeneous.

Chapter One Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry 39 A heterogeneous mixture: varies in composition and/or properties from one part of the mixture to another. Adhesive tape, CD, pen, battery, chair, and people are examples of heterogeneous mixtures. Classifying Matter

Chapter One Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry 40 matter Substances Mixtures ElementsCompoundsHeterogeneousHomogeneous Classifying Matter

Chapter One Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry States of Matter: Matter is present in three states: 1- a gas 2- a liquid 3- a solid. Gases: take the shape and volume of their container, and can be compressed to form liquids Liquids: take the shape of their container, but they do have their own volume. Solids :are rigid and have a definite shape and volume. Matter and Classification of Matter

Chapter One Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry Copyri ght © Cengag e Learnin g. All rights reserve d The Three States of Water

Chapter One Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry Three States of Matter 1.5

Chapter One Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry 44 Physical and Chemical Properties A physical property is the property displayed by the matter as the matter does not undergo any change in the composition. Physical properties include mass, color, volume, temperature, density, melting point, etc. A Chemical property is the property displayed by the matter as the matter undergoes a change in composition. Flammability, toxicity, reactivity, acidity are all chemical properties.

Chapter One Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry 45 In a physical change, there is no change in composition. No new substances are formed. Examples include: evaporation; melting; cutting a piece of wood; dissolving sugar in water. In a chemical change or chemical reaction, the matter undergoes a change in composition. New substances are formed. Examples include: burning gasoline; dissolving metal in acid; spoilage of food. The liquid fuel evaporates: a physical change. The vapor burns, combining with oxygen: a chemical change. Physical and Chemical Properties

Chapter One Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry 46 Q-Which of the following does not represent a chemical change? A)iron rusting B)reaction of sodium metal with water C)dissolving sugar in water D) souring of milk F)leaves changing color Q-Which of the following does not represent a physical property: A) boiling point B) odor C) density D) reaction with oxygen. F) solubility in water Physical and Chemical Properties