Chem101 General Chemistry I PDF

CHEM101 General Chemistry I  Chapter 1 Chemical Foundations Section 1.1 Chemistry: An Overview Outline 1. Overview about Chemistry 2. Units of Measurements 3. Uncertainty in Measurements 4. Significant figures and Calculations 5. Dimensional analysis 6. Temperature and Density ...

CHEM101 General Chemistry I  Chapter 1 Chemical Foundations Section 1.1 Chemistry: An Overview Outline 1. Overview about Chemistry 2. Units of Measurements 3. Uncertainty in Measurements 4. Significant figures and Calculations 5. Dimensional analysis 6. Temperature and Density Section 1.1 Chemistry: An Overview Atoms vs. Molecules  Matter is composed of tiny particles called atoms.  Atom: smallest part of an element that is still that element.  Molecule: Two or more atoms joined and acting as a unit. 4 Section 1.1 Chemistry: An Overview Oxygen and Hydrogen Molecules Use subscripts when more than one atom is in the molecule. 5 Section 1.1 Chemistry: An Overview A Chemical Reaction  One substance changes to another by reorganizing the way the atoms are attached to each other. 6 Section 1.3 Units of Measurement Nature of Measurement Measurement Quantitative observation consisting of two parts.  number  scale (unit) Examples  20 grams  6.63 × 10-34 joule·second 7 Section 1.3 Units of Measurement The Fundamental SI Units (SI: International System of Units) Physical Quantity Name of Unit Abbreviation Mass kilogram kg Length meter m Time second s Temperature kelvin K Electric current ampere A Amount of substance mole mol Luminous intensity candela cd 8 Section 1.3 Units of Measurement Prefixes Used in the SI System Prefixes are used to change the size of the unit. 9 Section 1.3 Units of Measurement Prefixes Used in the SI System 10 Section 1.3 Units of Measurement Mass ≠ Weight  Mass is a measure of the resistance of an object to a change in its state of motion. Mass does not vary.  Weight is the force that gravity exerts on an object. Weight varies with the strength of the gravitational field. 11 Section 1.3 Units of Measurement CONCEPT CHECK! S 1 X103  1 kg = __________________________ = 1000 g g a  5 m= ___________________________ SX109 =5000, 000 000 nm , # 200x100  200 µg = ________________________ 0 0002 -.g  1000 mL = _______________________ & L / · 9 1x10 0 1  1 dm= __________________________ =. m 3x108 3000000  3 Mg= __________________________ = g g Section 1.4 Uncertainty in Measurement  A digit that must be estimated in a measurement is called uncertain.  A measurement always has some degree of uncertainty. It is dependent on the precision of the measuring device.  Record the certain digits and the first uncertain digit (the estimated number). 13 Section 1.4 Uncertainty in Measurement Measurement of Volume Using a Buret  The volume is read at the bottom of the liquid curve (meniscus).  Meniscus of the liquid occurs at about 20.15 mL.  Certain digits: 20.15  Uncertain digit: 20.15 14 Section 1.4 Uncertainty in Measurement Practice: record the volume of the liquid in the graduated (measuring) cylinder? - - -s certain 21.54 / digits 31 5 uncertain 21 59.. 1 digit Section 1.4 Uncertainty in Measurement Class activity (Moodle) (1) (2) (3) (4) (5) (6) --- - - # & · 12. _______ &2 mL _______ mL ______. 7 2 mL ______ 58 2 mL _______. 1 285 mL 20 43 mL _______... 0 Oth L ________. _______ cm3 ______ m3 _______ dm3 ______μL ________ nL https://www.youtube.com/watch?v=sObrGonT71k 1 Section 1.4 Uncertainty in Measurement Precision and Accuracy Accuracy Agreement of a particular value with the true value. Precision Degree of agreement among several measurements of the same quantity. 17 Section 1.4 Uncertainty in Measurement Precision and Accuracy 18 Section 1.4 Uncertainty in Measurement Example  a. A student obtained a weight measurement of 2.85 g for a given substance. If the actual or known weight is 5.20 g, is the measurement accurate or inaccurate? Explain your answer student obtained is far because the measurement that the weight accurate from the actual value in accurate the value difference is enormous - 5 20 -2.. 85 = 2 35-.  b. If the student repeated the measurements three times and he obtained: 2.84 g, 2.80 g, and 2.83 g. Is the measurements precise - > - or imprecise? Justify your answer. precise. because the measurement imprecise Section 1.4 Uncertainty in Measurement CONCEPT CHECK! Salim analyzed calcium continent in food sample and he found the following results:  14.92% - average-1190 precs  14.91% - -  14.88%  14.91% - The actual amount of calcium is 15.70%. Comment on the precision and accuracy of the result. high precision. low accuracy Section 1.5 Significant Figures and Calculations Rules for Counting Significant Figures 1. Nonzero integers always count as significant figures.  3456 has 4 sig figs (significant figures). 2. There are three classes of zeros. 5 a. Leading zeros are zeros that precede all the nonzero digits. These do not count as significant figures.  0.048 X hasO 2 sig figs. 389 902 , ↓ b. Captive zeros are zeros between14 nonzero digits. These always count as significant figures.  16.07 has O & 4 sig figs. 21 Section 1.5 Significant Figures and Calculations c. Trailing zeros are zeros at the right end of the number. They are significant only if the number contains a decimal point.  9.300 - has 4 sig figs. - ↓ - decimal point  150 has 2 sig figs. -- X 3. Exact numbers have an infinite number of significant figures.  1 inch = 2.54 cm, exactly.  9 pencils (obtained by counting). 22 Section 1.5 Significant Figures and Calculations Exponential Notation (or scientific notation) ↳ So ??  Example -  300. written as 3.00 × 102  Contains three significant figures  Two Advantages  Number of significant figures can be easily indicated.  Fewer zeros are needed to write a very large or very small number. 23 Section 1.5 Significant Figures and Calculations CONCEPT CHECK!  How many significant figures are in each of the following measurements? 3001 g s f 4. 0.0320 m3 35. f 6.0 x 104 molecules G S. F 50 kg Is f 50. kg 2 Sof 24 mL 25 f.  13 9575 -. ⑮ - 5 s. f ↑ Sof 13 958. 14. 96 35. f 2 sof 14 0. 14 balance electrical balance Top loading 25. 159 0. 51389 1. 342 X 55. = 1 381. - 74. 2 Sof = 4 Sf. - the Same Y He as least of for - least the answer 23. 145 + 7 83. + 31 275. - 31. 28 3 d p. 2 d p. 3 dip 3d pdf. Section 1.5 Significant Figures and Calculations CONCEPT CHECK!  Do the following calculations: odp 2dp S · 83. 16 - - 83 XX 1002 - 10 Oh cm dp · No siz 3 Y I0m 5 8. X100 0 189. 18431428 4 :  How to1.5 Section measure liquid volume in chemistry Lab?? Significant Figures and Calculations Section 1.5 Volume Significant Figures and Calculations  Volume unit is not fundamental SI unit but is derived from length ↳  A cube of 1.0 m edge has a volume of 1.0 m × ↳ 1.0 m × 1.0 m = 1.0 m3 Length: 10 dm=1m Volume: (10 dm)3=(1m)3 1000 dm3=1m3 1 dm3 is called 1 Liter 1 dm3 = 1 Liter (L) 1 m3 = 1000 L 1000 cm3 = 1L Section 1.7 Dimensional Analysis  Use when converting a given result from one system of units to another.  To convert from one unit to another, use the equivalence statement that relates the two units.  Derive the appropriate unit factor by looking at the direction of the required change (to cancel the unwanted units).  Multiply the quantity to be converted by the unit factor to give the quantity with the desired units. 31 Section 1.7 Dimensional Analysis Example #1 by A - A ball has a mass of 6.8 kg. what is the mass in grams? 32 Section 1.7 Dimensional Analysis Excercise An iron sample has a volume of 4.50 mL. What is the volume of this sample in m3?. 50 4 mi m 1000 dm3 = 1m 1000 l 1000dm3 = 10 some X mat = > - 1. 103L 1 m3 = -> 4 50. X150 33 Section 1.7 Dimensional Analysis Use dimensional analysis to solve the below questions:  Q (1): convert 10.2 m/s to km/h ----  Q (2): convert 12L to cm3  Q (3) : convert 903.3 nm to μm (4) 10 2. mis-koth - 10. 2 mIh = 35 72 km/h. am 128 12000 am lifter 1000 = (2) 12 lifter = 24 cm 131 nm-Mm nm = m =Mm Im = 10"um um > - m Im = 100 Mm 903 3 m ? 109. m &3 x1. 109 - 9. 033x10"-m 903. 3 am = 9 033. X7 m m - Mne 9 033 X107 ? Um S - -. I - 10  0 9033. Mm 903 3. nm - 0 9033. Im Section 1.8 Temperature Three Systems for Measuring Temperature  Fahrenheit  Celsius  Kelvin 35 Section 1.8 Temperature The Three Major Temperature Scales · Section 1.8 Temperature Converting Between Scales TK  TC + 273.15 TC  TK  273.15 o 9oF TC   o  5 TF  32 F o 9F C TF  TC  o + 32oF 5C 37 Section 1.8 Temperature EXERCISE! At what temperature does °C = °F? ° % 0 c = 273 15 F. 38 Section 1.8 Temperature CONCEPT CHECK! A child has a body temperature of 38.7 ºC. If normal body temperature is 310.2 K, does the child has fever? i -F 7+ 273 38 15 %. 31 85%... he has fever Section 1.9 Density  Mass of substance per unit volume of the substance. -  Common units are g/cm3 or g/mL. S - mass Density = volume 40 Section 1.9 Density Example #1 A certain mineral has a mass of 17.8 g and a volume of 2.35 cm3. What is the density of this mineral? mass Density = volume 17.8 g Density = 2.35 cm3 3 Density = 7.57 g/cm 41 Section 1.9 Density Example #2 What is the mass of a 49.6 mL sample of a liquid, which has a density of 0.85 g/mL? mass Density = volume x 0.85 g/mL = 49.6 mL mass = x = 42 g 42 Section 1.9 Density CONCEPT CHECK!  A piece of platinum metal with a density of 21.5 g/cm3 has a volume of 4.49 cm3. What is its mass? d X- = m = d XV 5 X 9 49 Gl.. = = 96. 59 Section 1.9 Density CONCEPT CHECK! Ar = Vf-Vi = 33 - 25 Au = 8 rub 19 O go se d = m. - 6g1cm Section 1.10 Classification of Matter Matter & -  Anything occupying space and having mass.  Matter exists in three states.  Solid  Liquid  Gas 45 Section 1.10 Classification of Matter The Three States of Water 46 Section 1.10 Classification of Matter Solid & tough  Rigid  Has fixed volume and shape. vo sa 47 Section 1.10 Classification of Matter shape container Liquid > - - - *  Has definite volume but no specific shape. ·  Assumes shape of container. 48 Section 1.10 Classification of Matter shape Gas - container Volume  Has no fixed volume or shape.  Takes on the shape and volume of its container. 49 Section 1.10 Classification of Matter Mixtures  Have variable composition. Homogeneous Mixture -  Having visibly indistinguishable parts; solution. Heterogeneous Mixture -  Having visibly distinguishable parts. 50 Section 1.10 Classification of Matter CONCEPT CHECK! Which of the following is a homogeneous mixture?  Pure water  Gasoline  Jar of jelly beans  Soil  Copper metal 51 Section 1.10 Classification of Matter Physical Change  Change in the form of a substance, not in its chemical composition.  Example: boiling or freezing water  Can be used to separate a mixture into pure compounds, but it will not break compounds into elements.  Distillation  Filtration  Chromatography 52 Section 1.10 Classification of Matter Chemical Change  A given substance becomes a new substance or substances with different properties and different composition.  Example: Bunsen burner (methane reacts with oxygen to form carbon dioxide and water) 53 Section 1.10 Classification of Matter CONCEPT CHECK! burning ↳ Which of the following are examples of a chemical change?  Pulverizing (crushing) rock salt  Burning of wood > physical  Dissolving of sugar in water - change  Melting a popsicle on a warm summer day 54 Section 1.10 Classification of Matter The Organization of Matter 55