Welcome to Chem103 Required Items Textbook: Chemistry: The Molecular Nature of Matter and Change, Martin S. Silberberg, 5 th Edition, McGraw-Hill, 2009 iclicker Scientific calculator ACTIVE PARTICIPATION in class and lab Use of iclicker In each lecture, a handful of questions will be asked and you would need to respond to with the clickers. Your responses to questions will be recorded. The purpose behind the clickers is primarily to encourage you to think and respond to questions. You will be awarded 80% for participation and an additional 20% for answering the questions correctly. Your participation will also be used to monitor your attendance in lecture. The clicker responses will be used to award up to 3 extra-credit points to your final semester grade. Therefore, please bring your clickers to every class. The clickers are available for purchase at the University Bookstore. The University has adopted iclicker as the campus standard. So you will need to purchase a single iclicker for all of your classes. 1
Course Policies Lecture attendance will be monitored according to the University policy. NO MAKE-UPS for labs, quizzes, or exams. Homework assignments mentioned in the course syllabus will not be collected and graded. However, the homework assignments that will be handed over during class will be collected and graded. Must complete all lab work to pass the course. Suggestions Read the assigned section(s) of the text thoughtfully before they are discussed in the lecture. Listen carefully to the lecture and take notes of important topics. Taking good notes during a class is an important part of study preparation. Discuss with your classmates about topics that you are having difficulties to understand. I believe students can learn a lot through discussions with their classmates. Work all the recommended end-of-chapter exercises. Think about the problem and your answer. Check your answers against those at the back of the book but DO NOT look at those before trying the problem. FINALLY, please do not wait TOO LONG to get help. Don t hesitate to seek help from me if you are having any problem in understanding the lecture material. Feel free to drop me an email or simply stop by my office if you have any questions. One-to-one conversation is sometime helpful to understand the difficult topics. Goals and Expectations Goals Develop an atomic/molecular level picture of matter Use the atomic/molecular level picture to explain chemical and physical properties of matter Develop practical lab skills Expectations coming in Understand Chapter 1 Know the metric units and prefixes (Tables 1.3 and 1.4) Comfortable with scientific notation Competent with basic algebraic manipulations Know how to use your calculator Know the names and symbols for elements 1-88 2
Keywords Matter Physical and Chemical properties Physical and Chemical changes Chapter 1 Qualitative and quantitative observations Units of measurements Precision, Accuracy, and Experimental Error Scientific notation and Significant figures Matter at the Macroscopic and Particulate Levels Chemistry & Matter We can explore the MACROSCOPIC world what we can see to understand the PARTICULATE (microscopic) worlds we cannot see. We write SYMBOLS to describe these worlds. We build up MODELS of their interactions Predict MACROSCOPIC properties 3
Matter and its Reactivity 2Na(s) + Cl 2 (g) 2NaCl(s) Chemistry is the study of the properties and transformations of matter. Physical Properties What are some physical properties? color melting and boiling point Odor Density Physical Changes Some physical changes would be boiling of a liquid melting of a solid dissolving a solid in a liquid to give a homogeneous mixture a SOLUTION. 4
Chemical Properties and Chemical Changes Chemical change or chemical reaction transformation of one or more atoms or molecules into one or more different molecules. Physical or Chemical Changes? 1. A molecule disintegrates upon heating? 2. Two molecules react and form new molecule Physical or Chemical Changes? 1. Molecules form new interactions upon cooling 2. Molecules breaks up these interactions upon heating 5
Physical or Chemical Changes? Physical or Chemical Changes? 1. Formation of snow 2. Breaking of glass 3. Corroding metal Physical or Chemical Changes? 4. A rusting bicycle 5. Melting butter for popcorn 6. Bleaching your hair 6
Physical or Chemical Changes? 7. Fireworks exploding 8. Squeezing oranges to make orange juice 9. Boiling egg Intensive and Extensive Properties INTENSIVE property of matter does NOT depend on quantity of matter. Example: Density is an intensive property of matter. Temperature EXTENSIVE property of matter depends on quantity of matter. Example: mass and volume. Types of Observations and Measurements We make QUALITATIVE observations of reactions changes in color and physical state. We also make QUANTITATIVE MEASUREMENTS, which involve numbers. For example, if 10.00 g of iron reacts with 8.0 g of oxygen, how much iron oxide will form? 7
Some problems All of the following are examples of intensive properties EXCEPT a. melting point. b. color. c. volume. d. density. e. boiling point. Which of the following observations are examples of chemical changes to aluminum? a. When aluminum reacts with hydrochloric acid, hydrogen gas is evolved. b. Aluminum melts at 660 C. c. A cube of aluminum with a volume of 4.0 cm 3 has a mass of 10.8 g. d. Aluminum is a good electrical conductor. Which one of the following is an example of physical change? a. the evaporation of water b. the rusting of iron c. the combustion of hydrogen d. the tarnishing of silver e. both the rusting of iron and the tarnishing of silver The Importance of Energy in the Study of Matter Energy is the ability to do work Potential energy: energy due to the position of the object Kinetic energy: energy due to the motion of the object Energy is neither created nor destroyed-it d is always conserved as it is converted from one form to the other In nature, situations with lower energy is favored over those of higher energy Potential Energy is Converted to Kinetic Energy 8
Potential Energy is Converted to Kinetic Energy The Scientific Approach: Developing a Model Units of Measurement Use SI units based on the metric system 9
Units of Length 1 kilometer (km) =? meters (m) 1 meter (m) =? centimeters (cm) 1 centimeter (cm) =? millimeter (mm) 1 nanometer (nm) = 1.0 x 10-9 meter O H distance = 9.58 x 10-11 m 9.58 x 10-9 cm 0.0958 nm Units of Length 1. Express 100 Km in cm a. 10 7 b. 10 6 c. 10 4 d. 10 2 1 Å = 10 10 m=10 1 nm 3. Express 10 nm in Å a. 10 2 b. 10 2 c. 10 4 d. 10 4 2. Express 10 nm in cm a. 10 2 b. 10 4 c. 10 3 d. 10 6 1 pm =10 12 m = 10 3 nm 4. Express 10 nm in pm a. 10 2 b. 10 4 c. 10 3 d. 10 6 Temperature Scales Boiling point of water Fahrenheit 212 F 180 F Celsius 100 C 100 C Kelvin 373 K 100 K Freezing point of water 32 F 0 C 273 K Notice that 1 kelvin degree = 1 degree Celsius 10
Fahrenheit Temperature Scales Celsius Kelvin F -32 C = C = K 273 9 5 32 F =A. 100 C B. 9 C C. 0 C D. -17.7 C 0 K = A. -273 C B. 305 C C. 0 C D. -305 C Calculations Using Temperature Generally require temp s in kelvins T (K) = T ( C) + 273.15 Body temp = 37 C + 273.15 = 310.15 K Liquid nitrogen = -196 C + 273.15 = 77.15 K Playing with Numbers 1. What is 5-2 equal to? A. 10 B. -1/25 C. 1/25 D. -25 E. -1/64 F. none of the above 3. Write the following number so it has three significant figures: 340 A. 340 B. 3.40 x 10 2 C. 340 x 10-2 D. 3.4 x 10 2 2. Round the following number to three decimal places: 12.333333333 A. 12.3 B. 12.33 C. 12.333 D. 12.334 E. 12.330 4. 8.66 x 10 4 x 4.1 x 10 2 =? A. 3.6 x 10 7 B. 3.5 x 10 7 C. 3.55 x 10 7 D. 3.5506 x 10 6 E. 3.550 x 10 6 11
Playing with Numbers 5. 3.56x10 2 + 1.92x10 3 =? (in proper scientific notation) A. 5.48x10 2 B. 2.28x10 3 C. 2.276x10 3 D 22 76x10 2 6. Round the following number to four significant figures: 38219.99147 A. 38219.9915 B. 38219.9914 C. 3822 D. 38210 E. 38220 D. 22.76x10 B. 34.8 7. Compute the following: 3.22+6.2*5.101 (pay attention to significant figures after each step) A. 35.2 B 34 8 C. 35 D. 48 E. 48.1 Dimensional Analysis If the temperature of a hot water bath is 40.5 C, what is the temperature in Kelvin? In Fahrenheit? Remember, T (K) = T ( C) + 273.15 Answer: 313.7 K and 105. F Dimensional Analysis PROBLEM: Mercury (Hg) has a density of 13.6 g/cm 3. What is the mass of 95 ml of Hg in grams? In pounds? First, note that 1 cm 3 = 1 ml 12
PROBLEM: Mercury (Hg) has a density of 13.6 g/cm 3. What is the mass of 95 ml of Hg in grams? In pounds? Strategy 1. Use density to calc. mass (g) from volume. Density = mass (g) volume (cm3) Volume x density = mass ( 95 cm 3 )(13.6 g/cm 3 ) = 1.3 x 10 3 g PROBLEM: Mercury (Hg) has a density of 13.6 g/cm3. What is the mass of 95 ml of Hg in grams? In pounds? 2. Convert mass (g) to mass (lb) Need to know conversion factor = 454 g / 1 lb 1.3 x 10 3 g 1 lb 454 g = 2.8 lb Number in original unit x new unit = New number in new unit original unit Dimensional Analysis A can of Coca-Cola contains 12 quarts (qt). What is the volume in fluid ounces (fl oz)? (1qt 32 fl oz) Number in original i unit x new unit = New number in new unit original unit 12 fl oz x 1 qt 32 fl oz = 0.38 qt 13
Dimensional Analysis A marathon race covers a distance of 42.195 km. What is this distance in meters? In miles? ( 1 km 0.62140 miles) A. 4.2195 x 10 4 m B. 4.22 x 10 4 m C. 4.2195 x 10-4 m D. 4.219 x 10 4 m A. 26.219 miles B. 67.903 miles C. 26.22 miles D. 67.90 miles Dimensional Analysis A marathon race covers a distance of 42.2 km. What is this distance in meters? In miles? ( 1 km 0.6214 miles) A. 4.2195 x 10 4 m B. 4.22 x 10 4 m C. 4.2195 x 10-4 m D. 4.219 x 10 4 m A. 26.219 miles B. 67.903 miles C. 26.22 miles D. 67.90 miles Dimensional Analysis How many Å 3 are there in 50. m 3? (1 Å =10-10 m) A. 5.0 x 10 31 Å 3 B. 5.0 x 10-31 Å 3 C. 5 x 10 11 Å 3 D. 5x10-11 Å 3 Convert the 50.m 3 volume in L? ( 1 m = 10 2 cm; 1000 cm 3 = 1L) A. 5.0 L B. 5.0 x 10 2 L C. 5.0 x 10 3 L D. 50. x 10 3 L 14
Exponential or Scientific notation Exponential or Scientific notation: Presenting a very large or small numbers in a compact and consistent form for simplification in calculations. Example: Speed of light = 299800000 m s -1 (a very big number!) A red blood cell has a diameter of 0.0000075 m (a very small number!) Speed of light = 2.998 x 10 8 ms -1 (in a compact form!) A red blood cell diameter = 7.5 x 10-6 m Scientific notation: expressed as a product of two numbers: N x 10 n, where N is the digit term and 10 n, the exponential term. Significant Figures Significant figures are digits in a measured quantity (expressed in a scientific notation) that reflect the accuracy of the measurement. Scientific notation Sig. Figs. 0.0156 0.1560 15600 Zeros at the left of a nonzero number are not significant Zeros at the right of a nonzero number (trailing zero) are significant provided there is decimal point before the nonzero number. Significant Figures a. 1.567 cm + 2.4791 cm + 1.25 cm 1.567 (4 sig figs, three digits after the decimal) 2.4971 (5 sig figs, four digits after the decimal), most precise 1.25 (3 sig figs, 2 digits after the decimal point), least precise Sum: 5.3141, corrected to 5.31 cm b. 315.15 ml + 28 ml = 343. ml c. 0.120 cm x 0.08206 cm = 0.202 cm 2 d. 241.0/23.5 = 10.3 15
Dimensional Analysis 1 mole of a substance is typically expressed by the MW of any chemical in grams? Atomic weight of sodium is 22.9898 and that of chlorine is 35.4527. What is the MW of NaCl? A. 58.4425 B. 58.443 C. 58.4 You were asked to weigh 5.03 moles of NaCl. What is the amount in grams? A. 294 B. 293.9 L C. 293.977 L Dimensional Analysis 5.03 moles of NaCl is dissolved in 1L of water. What is the concentration in g/l? A. 294 B. 5.03 C. 58.4 D. No idea In mol/l A. 294 B. 5.03 C. 58.4 D. Not sure Dimensional Analysis A piece of metal has a density of 2.65 g/cm 3 and a mass of 2.50 g. What is the volume of the piece of metal in liter? (1 liter = 1000 cm 3 ) A. 0.94 x 10-3 L B. 9.4 x 10 +3 L C. 9.4 x 10-3 L D. 0.94 x 10 +3 L 16
Precision, Accuracy, and Experimental Error Precision: how close the measurements in a series are to each other Accuracy: how close a measurement is to the actual value Error: Deviation from actual value Systematic Error and Random Error Scientific notation and Significant figures Average value of a variable x : Group A reported: 5.43333 ± 0.00003 Group B reported: 5.23333 ± 0.00345 Group C reported: 5.33333 ± 0.0000100001 The real value was 5.2. Whose measurement was least precise? A. B. C. Whose measurement was most accurate? A. B. C. Scientific notation and Significant figures Average value of a variable x : Group A reported: 5.43333 ± 0.00003 Group B reported: 5.23333 ± 0.00345 Group C reported: 5.33333 ± 0.0000100001 The real value was 5.2. Whose measurement was most precise? A. B. C. Whose measurement was least accurate? A. B. C. 17