1. © 2015 Pearson Education, Inc. Chapter 1 Introduction: Matter and Measurement James F. Kirby Quinnipiac University Hamden, CT Lecture Presentation

2. Matter And Measurement © 2015 Pearson Education, Inc. Chemistry Chemistry is the study of the properties and behavior of matter. It is central to our fundamental understanding of many science-related fields.

3. Matter And Measurement © 2015 Pearson Education, Inc. Matter Matter is anything that has mass and takes up space.

4. Matter And Measurement © 2015 Pearson Education, Inc. Matter Atoms are the building blocks of matter. Each element is made of a unique kind of atom. A compound is made of two or more different kinds of elements. Note: Balls of different colors are used to represent atoms of different elements. Attached balls represent connections between atoms that are seen in nature. These groups of atoms are called molecules.

5. Matter And Measurement © 2015 Pearson Education, Inc. Methods of Classification State of Matter Composition of Matter

6. Matter And Measurement © 2015 Pearson Education, Inc. States of Matter  The three states of matter are 1)solid. 2)liquid. 3)gas.  In this figure, those states are ice, liquid water, and water vapor.

7. Matter And Measurement © 2015 Pearson Education, Inc. Classification of Matter Based on Composition Matter And Measurement  If you follow this scheme, you can determine how to classify any type of matter.  Homogeneous mixture  Heterogeneous mixture  Element  Compound

8. Matter And Measurement © 2015 Pearson Education, Inc. Classification of Matter—Substances A substance has distinct properties and a composition that does not vary from sample to sample. The two types of substances are elements and compounds.  An element is a substance which can not be decomposed to simpler substances.  A compound is a substance which can be decomposed to simpler substances.

9. Matter And Measurement © 2015 Pearson Education, Inc. Compounds and Composition Compounds have a definite composition. That means that the relative number of atoms of each element that makes up the compound is the same in any sample. This is The Law of Constant Composition (or The Law of Definite Proportions).

10. Matter And Measurement © 2015 Pearson Education, Inc. Classification of Matter—Mixtures Mixtures exhibit the properties of the substances that make them up. Mixtures can vary in composition throughout a sample (heterogeneous) or can have the same composition throughout the sample (homogeneous). Another name for a homogeneous mixture is solution.

11. Matter And Measurement © 2015 Pearson Education, Inc. SAMPLE EXERCISE 1.1 Distinguishing among Elements, Compounds, and Mixtures “White gold,” used in jewelry, contains two elements, gold and palladium. Two different samples of white gold differ in the relative amounts of gold and palladium that they contain. Both are uniform in composition throughout. Without knowing any more about the materials, use Figure 1.9 to characterize and classify white gold.Figure 1.9 Solution Because the material is uniform throughout, it is homogeneous. Because its composition differs for the two samples, it cannot be a compound. Instead, it must be a homogeneous mixture. Gold and palladium can be said to form a solid solution with one another.

12. Matter And Measurement © 2015 Pearson Education, Inc. Types of Properties Physical Properties can be observed without changing a substance into another substance. ◦Some examples include boiling point, density, mass, or volume. Chemical Properties can only be observed when a substance is changed into another substance. ◦Some examples include flammability, corrosiveness, or reactivity with acid.

13. Matter And Measurement © 2015 Pearson Education, Inc. Types of Properties Intensive Properties are independent of the amount of the substance that is present. ◦Examples include density, boiling point, or color. Extensive Properties depend upon the amount of the substance present. ◦Examples include mass, volume, or energy.

14. Matter And Measurement © 2015 Pearson Education, Inc. Types of Changes Physical Changes are changes in matter that do not change the composition of a substance. ◦Examples include changes of state, temperature, and volume. Chemical Changes result in new substances. ◦Examples include combustion, oxidation, and decomposition.

15. Matter And Measurement © 2015 Pearson Education, Inc. Changes in State of Matter  Converting between the three states of matter is a physical change.  When ice melts or water evaporates, there are still 2 H atoms and 1 O atom in each molecule.

16. Matter And Measurement © 2015 Pearson Education, Inc. Chemical Reactions (Chemical Change) In the course of a chemical reaction, the reacting substances are converted to new substances. Here, the elements hydrogen and oxygen become water.

17. Matter And Measurement © 2015 Pearson Education, Inc. Separating Mixtures Mixtures can be separated based on physical properties of the components of the mixture. Some methods used are  filtration.  distillation.  chromatography.

18. Matter And Measurement © 2015 Pearson Education, Inc. Filtration In filtration, solid substances are separated from liquids and solutions.

19. Matter And Measurement © 2015 Pearson Education, Inc. Distillation Distillation uses differences in the boiling points of substances to separate a homogeneous mixture into its components.

20. Matter And Measurement © 2015 Pearson Education, Inc. Chromatography This technique separates substances on the basis of differences in the ability of substances to adhere to the solid surface, in this case, dyes to paper.

21. Matter And Measurement © 2015 Pearson Education, Inc. Numbers and Chemistry Numbers play a major role in chemistry. Many topics are quantitative (have a numerical value). Concepts of numbers in science  Units of measurement  Quantities that are measured and calculated  Uncertainty in measurement  Significant figures  Dimensional analysis

22. Matter And Measurement © 2015 Pearson Education, Inc. Units of Measurements—SI Units Système International d’Unités (“The International System of Units”) A different base unit is used for each quantity.

23. Matter And Measurement © 2015 Pearson Education, Inc. Units of Measurement—Metric System  The base units used in the metric system Mass: gram (g) Length: meter (m) Time: second (s or sec) Temperature: degrees Celsius ( o C) or Kelvins (K) Amount of a substance: mole (mol) Volume: cubic centimeter (cc or cm 3 ) or liter (l)

24. Matter And Measurement © 2015 Pearson Education, Inc. Units of Measurement— Metric System Prefixes  Prefixes convert the base units into units that are appropriate for common usage or appropriate measure.

25. Matter And Measurement © 2015 Pearson Education, Inc. SAMPLE EXERCISE 1.2 Using Metric Prefixes What is the name given to the unit that equals (a) 10 –9 gram, (b) 10 –6 second, (c) 10 –3 meter? Solution In each case we can refer to Table 1.5, finding the prefix related to each of the decimal fractions: (a) nanogram, ng, (b) microsecond,  s (c) millimeter, mm.Table 1.5

26. Matter And Measurement © 2015 Pearson Education, Inc. Mass and Length These are basic units we measure in science. Mass is a measure of the amount of material in an object. SI uses the kilogram as the base unit. The metric system uses the gram as the base unit. Length is a measure of distance. The meter is the base unit.

27. Matter And Measurement © 2015 Pearson Education, Inc. Volume Note that volume is not a base unit for SI; it is derived from length (m × m × m = m 3 ). The most commonly used metric units for volume are the liter (L) and the milliliter (mL). A liter is a cube 1 decimeter (dm) long on each side. A milliliter is a cube 1 centimeter (cm) long on each side, also called 1 cubic centimeter (cm × cm × cm = cm 3 ).

28. Matter And Measurement © 2015 Pearson Education, Inc. Temperature  In general usage, temperature is considered the “hotness and coldness” of an object that determines the direction of heat flow.  Heat flows spontaneously from an object with a higher temperature to an object with a lower temperature.

29. Matter And Measurement © 2015 Pearson Education, Inc. 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. The kelvin is the SI unit of temperature. –It is based on the properties of gases. –There are no negative Kelvin temperatures. –The lowest possible temperature is called absolute zero (0 K). K =  C + 273.15

30. Matter And Measurement © 2015 Pearson Education, Inc. Temperature The Fahrenheit scale is not used in scientific measurements, but you hear about it in weather reports! The equations below allow for conversion between the Fahrenheit and Celsius scales: –  F = 9/5(  C) + 32 –  C = 5/9(  F − 32)

31. Matter And Measurement © 2015 Pearson Education, Inc. SAMPLE EXERCISE 1.3 Converting Units of Temperature If a weather forecaster predicts that the temperature for the day will reach 31°C, what is the predicted temperature (a) in K, (b) in °F? Solution (a) Using Equation 1.1, we have K = 31 + 273 = 304 K (b) Using Equation 1.2, we have

32. Matter And Measurement © 2015 Pearson Education, Inc. Density Density is a physical property of a substance. It has units that are derived from the units for mass and volume. The most common units are g/mL or g/cm 3. d = m/V

33. Matter And Measurement © 2015 Pearson Education, Inc. SAMPLE EXERCISE 1.4 Determining Density and Using Density to Determine Volume or Mass (a) Calculate the density of mercury if 1.00  10 2 g occupies a volume of 7.36 cm 3. (b) Calculate the volume of 65.0 g of the liquid methanol (wood alcohol) if its density is 0.791 g/mL. (c) What is the mass in grams of a cube of gold (density = 19.32 g/ cm 3 ) if the length of the cube is 2.00 cm? Solution (a) We are given mass and volume, so Equation 1.3 yields (b) Solving Equation 1.3 for volume and then using the given mass and density gives (c) We can calculate the mass from the volume of the cube and its density. The volume of a cube is given by its length cubed: Solving Equation 1.3 for mass and substituting the volume and density of the cube, we have

34. Matter And Measurement © 2015 Pearson Education, Inc. Numbers Encountered in Science Exact numbers are counted or given by definition. For example, there are 12 eggs in 1 dozen. Inexact (or measured) numbers depend on how they were determined. Scientific instruments have limitations. Some balances measure to ±0.01 g; others measure to ±0.0001g.

35. Matter And Measurement © 2015 Pearson Education, Inc. SAMPLE EXERCISE 1.5 Relating Significant Figures to the Uncertainty of a Measurement What difference exists between the measured values 4.0 g and 4.00 g? Solution Many people would say there is no difference, but a scientist would note the difference in the number of significant figures in the two measurements. The value 4.0 has two significant figures, while 4.00 has three. This difference implies that the first measurement has more uncertainty. A mass of 4.0 g indicates that the uncertainty is in the first decimal place of the measurement. Thus, the mass might be anything between 3.9 and 4.1 g, which we can represent as 4.0 ± 0.1 g. A measurement of 4.00 g implies that the uncertainty is in the second decimal place. Thus, the mass might be anything between 3.99 and 4.01 g, which we can represent as 4.00 ± 0.01 g. Without further information, we cannot be sure whether the difference in uncertainties of the two measurements reflects the precision or accuracy of the measurement.

36. Matter And Measurement © 2015 Pearson Education, Inc. Uncertainty in Measurements Different measuring devices have different uses and different degrees of accuracy. All measured numbers have some degree of inaccuracy.

37. Matter And Measurement © 2015 Pearson Education, Inc. 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.

38. Matter And Measurement © 2015 Pearson Education, Inc. 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.

39. Matter And Measurement © 2015 Pearson Education, Inc. Significant Figures 1.All nonzero digits are significant. 2.Zeroes between two significant figures are themselves significant. 3.Zeroes at the beginning of a number are never significant. 4.Zeroes at the end of a number are significant if a decimal point is written in the number.

40. Matter And Measurement © 2015 Pearson Education, Inc. SAMPLE EXERCISE 1.6 Determining the Number of Significant Figures in a Measurement How many significant figures are in each of the following numbers (assume that each number is a measured quantity): (a) 4.003, (b) 6.023  10 23, (c) 5000? Solution (a) Four; the zeros are significant figures. (b) Four; the exponential term does not add to the number of significant figures. (c) One. We assume that the zeros are not significant when there is no decimal point shown. If the number has more significant figures, a decimal point should be employed or the number written in exponential notation. Thus, 5000. has four significant figures, whereas 5.00  10 3 has three.

41. Matter And Measurement © 2015 Pearson Education, Inc. 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.

42. Matter And Measurement © 2015 Pearson Education, Inc. SAMPLE EXERCISE 1.7 Determining the Number of Significant Figures in a Calculated Quantity The width, length, and height of a small box are 15.5 cm, 27.3 cm, and 5.4 cm, respectively. Calculate the volume of the box, using the correct number of significant figures in your answer. Solution The volume of a box is determined by the product of its width, length, and height. In reporting the product, we can show only as many significant figures as given in the dimension with the fewest significant figures, that for the height (two significant figures): When we use a calculator to do this calculation, the display shows 2285.01, which we must round off to two significant figures. Because the resulting number is 2300, it is best reported in exponential notation, 2.3  10 3, to clearly indicate two significant figures.

43. Matter And Measurement © 2015 Pearson Education, Inc. SAMPLE EXERCISE 1.8 Determining the Number of Significant Figures in a Calculated Quantity A gas at 25°C fills a container whose volume is 1.05  10 3 cm 3. The container plus gas have a mass of 837.61 g. The container, when emptied of all gas, has a mass of 836.2 g. What is the density of the gas at 25°C? Solution To calculate the density, we must know both the mass and the volume of the gas. The mass of the gas is just the difference in the masses of the full and empty container: (837.61 – 836.2) g = 1.41 g → 1.4 g In subtracting numbers, we determine the number of significant figures in our result by counting decimal places in each quantity. In this case each quantity has one decimal place. Thus, the mass of the gas, 1.4 g, has one decimal place. Using the volume given in the question, 1.05  10 3 cm 3, and the definition of density, we have In dividing numbers, we determine the number of significant figures in our result by counting the number of significant figures in each quantity. There are two significant figures in our answer, corresponding to the smaller number of significant figures in the two numbers that form the ratio.