Presentation on theme: "Chapter 1 Introduction: Matter and Measurement"— Presentation transcript:
1 Chapter 1 Introduction: Matter and Measurement Chemistry, The Central Science, 10th editionTheodore L. Brown; H. Eugene LeMay, Jr.; and Bruce E. BurstenChapter 1 Introduction: Matter and MeasurementJohn D. BookstaverSt. Charles Community CollegeSt. Peters, MO 2006, Prentice Hall
2 Matter:Anything that has mass and takes up space.2
4 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.4
5 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.5
6 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.6
7 Chemical ReactionsIn the course of a chemical reaction, the reacting substances are converted to new substances.7
9 There are two types of units: SI UnitsThere are two types of units:fundamental (or base) units;derived units.There are 7 base units in the SI system.
10 SI Units Système International d’Unités Uses a different base unit for each quantity10
11 Metric SystemPrefixes convert the base units into units that are appropriate for the item being measured.11
12 The units for volume are given by (units of length)3. SI unit for volume is 1 m3.We usually use 1 mL = 1 cm3.Other volume units:1 L = 1 dm3 = 1000 cm3 = 1000 mL.
13 Uncertainty in Measurements Different measuring devices have different uses and different degrees of accuracy.13
14 Physical property of a substance Density:Physical property of a substanced=mV14
15 Do now: A graduated cylinder is filled with 15. 0 mL of water Do now: A graduated cylinder is filled with mL of water. An object with a mass of g causes the total volume to increase to 23.4 mL. What is the density of the sample?
16 Vocabulary review Mass : amount of matter in an object. It is measured with a balance.Unit in the SI system: grams gWeight: a measure of the pull that the gravity exerts over an object.If we stay in the same planet (same gravity) is used like the mass.
17 Volume The space that an object occupies. Unit of volume in SI Liter = L
18 What is density?Density is a comparison of how much matter there is in a certain amount of space.IT IS AN INTENSIVE PHYSICAL PROPERTY. It is used to identify a substance.
19 DENSITY OF WATER1g/mlThat means that a gram of water has a volume of 1 milliliter or 1 cubic centimeter.
20 Which one is more dense?Now which one is more dense?
21 What is density? Density = mass volume or mass ÷ volume. Units for density: gcm3Why are these the units for density?ALWAYS REMEMBER UNITS!
22 Let’s try a density problem together Find the density of a yellow rock has a mass of 8 g and a volume of 4 cm3.Use your table S to determine what element it could be!
23 IMMISCIBLE LIQUIDSIf you pour together liquids that don’t mix and have different densities, they will form liquid layers.Liquids that don’t mix are said to be IMMISCIBLEThe liquid with the highest density will be on the bottom.The liquid with the lowest density will be on the top.
24 Liquid Layers . Which layer has the highest density? Which layer has the lowest density?Imagine that the liquids have the following densities:10g/cm3. 3g/cm3.6g/cm3. 5g/cm3.Which number would go with which layer?Is any of the liquids water?
25 To measure the volume of an object If is a regular object measure the dimensions needed and use the formulacube= LxWxHCylinder = p h r2For an irregular object use the water displacement method.
26 Liquid Layers – Try with your neighbor Which liquid has the highest density?Which liquid has the lowest density?Which liquid has the middle density?
27 Liquid Layers – Try on your own! Imagine that the liquids on the right have the following densities:15g/cm g/cm33g/cm g/cm37g/cm g/cm3Match the colors to the correct densities.3g/cm37g/cm39g/cm310g/cm312g/cm315g/cm3
28 Review What is the formula for density? What happens if you pour together liquids that have different densities?Will the liquid on the top have the highest or lowest density?Will the liquid on the bottom have the highest or lowest density?
29 Density worksheet answers 1=12=23=2 D of Na g/mL4=4 D of Mg g/cm35=2g/24.4L = 0.82 g/L
30 HOMOGENEOUS : SAME PROPERTIES THROUGHOUT THE SAMPLE HETEROGENEOUS :DIFFERENT PROPERTIES IN DIFFERENT PARTS OF THE SAMPLE
31 PURE SUBSTANCES have a constant composition ELEMENTS – Made up of same kind of atoms. Could not be decomposed.COMPOUNDS – Made up of different kind of atoms CHEMICALLY COMBINED. Can be decomposed.Recognizable by formulas!
41 Pure Substances and Mixtures If matter is not uniform throughout, then it is a heterogeneous mixture.If matter is uniform throughout, it is homogeneous.If homogeneous matter can be separated by physical means, then the matter is a mixture.If homogeneous matter cannot be separated by physical means, then the matter is a pure substance.If a pure substance can be decomposed into something else, then the substance is a compound.
42 ElementsIf a pure substance cannot be decomposed into something else, then the substance is an element.There are 114 elements known.Each element is given a unique chemical symbol (one or two letters).Elements are building blocks of matter.The earth’s crust consists of 5 main elements. (O, Si, Al, Fe, Ca)The human body consists mostly of 3 main elements. (O, C, H)
69 Significant FiguresThe 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.
70 Uncertainty in Measurement All scientific measures are subject to error.These errors are reflected in the number of figures reported for the measurement.Precision and AccuracyMeasurements that are close to the “correct” value are accurate.Measurements that are close to each other are precise.
71 PRECISSION DEALS WITH REPRODUCIBILITY OF A MEASUREMENT. ACCURACY DEALS WITH THE EXACTESNESS OF THE MEASUREMENT, HOW CLOSE IT IS TO THE , TRUE, ACCEPTED OR STANDARD VALUEPRECISSION DEALS WITH REPRODUCIBILITY OF A MEASUREMENT.IF SEVERAL MEASUREMENTS GIVE A SIMILAR RESULT IT IS SAID THAT THE MEASUREMENT IS PRECISE
72 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.
73 October 5 UNCERTAINTY IN MEASUREMENT SIGNIFICANT FIGURES – Rules and examplesDO NOWCalculate the density of an object that has a mass of 10.0 g and a volume of 3.0 mL.
75 Significant FiguresThe number of digits reported in a measurement reflect the accuracy of the measurement and the precision of the measuring device.All the figures known with certainty plus one extra figure (estimated digit) are called significant figures.
76 Sig fig in calculations In any calculation, the results are reported to the fewest significant figures (for multiplication and division) or fewest decimal places (addition and subtraction).
77 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 or if they are to the right of a decimal point.
79 EXAMPLE FOR ADDITIONCopy and perform the following operation indicating the right number of sig fig121.20.2
80 MULTIPLICATION AND DIVISION 5 x 100 = x 745 = 3469/ 5799=
81 Examples: How many significant figures are in each of the following? kgs507 people230,050 cmA
82 Tell the number of significant digits in each of the following measurements. 1. 48 cm __________g __________m __________°C __________mm __________cm3__________g __________mm __________kg __________× 1015 sec __________× 10-4 m __________g __________
83 Tell the number of significant digits in each of the following measurements. 1. 48 cm __________g __________m __________°C __________mm __________cm3__________g __________mm __________kg __________× 1015 sec __________× 10-4 m __________g __________
84 How do scientist express the accuracy of a measurement? DO NOW : Observe the two instruments in my desk to measure volume, determine which would determine the volume of an Al cylinder with greater accuracy and explain in your notebook why.
85 Percent ErrorTo determine the accuracy of a measurement. It tells us how far our measured stands from an accepted or known value.% error = I measured value – accepted value I X 100___________________________________________accepted value
86 ExampleCalculate the percent error of the measurement for a student that determined that the density for Al is 2.5 g/mL. Hint use table T to determine the accepted value!
87 1) 3.482 cm + 8.51 cm + 16.324 cm ____________________ 2) g g g ____________________3) 80.4 cm cm ____________________4) 106.5mL mL ____________________5) 48.2 cm × 1.6 cm × 2.12 cm ____________________6) 8.3 m × 4.0 m × m
88 7) 64.34 cm3 ÷ 8.149 cm ____________________ 8) 4.93 mm2 ÷ mm ____________________9) 0 57 mL x 760 mm/740 mm x 273K/250 K10) g x amu/ a m u
89 Answers28.32 cmg63.9 cm76 mL160 cm333 m37.895 cm20.263 mm
91 1. According to an accepted chemistry reference 1. According to an accepted chemistry reference. the heat of vaporization of water is 540. calories per gram. A student determined in the laboratory that the heat of vaporization of water was 620. calories per gram. The student's results had a percent error of (1) 12.9, (2) 80.0, (3) 14.8, (4) 87.12. Which measurement contains a total of three significant figures?(1) 0.01 g (2) g (3) g (4) g
92 3. In an experiment the gram atomic mass of magnesium was determined to be Compared to the accepted value 24.3, the percent error for this determination was (1) , (2) 24.7, (3) 1.65, (4) 98.44. A student determined the melting point of a substance to be 55.2°C. If the accepted value is 50. 1°C the percent error in her determination is (1) 5.10, (2) 10.2, (3) 9.24, (4) 12.05. Using the rules for significant figures, the sum of gram and gram should be expressed as (1) gram, (2) 0.03 gram, (3) gram, (4) gram
93 6. Which milligram quantity contains a total of four significant figures? (1) mg (2) 3100 mg (2) 3010 mg (4) mg
94 Scientific NotationNumbers written in scientific notation include a numeral with one digit before the decimal point, multiplied by some power of ten (6.022 x 1023)In scientific notation, all digits are significant.You should be able to convert from non-scientific notation to scientific and vice-versa.
96 TEMPERATUREIs associated with heat but it is NOT HEAT. IT IS NOT A FORM OF ENERGY!!!! ( Heat is)Review: What is KINETIC ENERGY?
97 KINETIC ENERGY (KE) Is associated with movement. If an object is moving fast has high KEIf an object is moving slowly it has low KE
98 TemperatureIn scientific measurements, the Celsius and Kelvin scales are most often used.The Celsius scale is based on the properties of water.0C is the freezing point of water.100C is the boiling point of water.
99 Temperature:A measure of the average kinetic energy of the particles in a sample. If an object is at HIGH temperature its particles are moving FAST At LOW temperature particles move SLOWLY