1.-Introduction-to-Chemistry.docx

CHEMISTRY FOR ENGINEERS ======================= INTRODUCTION TO CHEMISTRY ========================= Module Outcomes: ================ - Explain the usefulness of the macroscopic, microscopic, and symbolic perspectives in understanding chemical systems. - Draw pictures to illustrate simpl...

CHEMISTRY FOR ENGINEERS ======================= INTRODUCTION TO CHEMISTRY ========================= Module Outcomes: ================ - Explain the usefulness of the macroscopic, microscopic, and symbolic perspectives in understanding chemical systems. - Draw pictures to illustrate simple chemical phenomena (like the differences among solids, liquids, and gases) on the molecular scale. - Explain the difference between inductive and deductive reasoning in your own words. - Use appropriate ratios to convert measurements from one unit to another. - Express the results of calculations using the correct number of significant figures. Module Content ============== - Macroscopic - Microscopic - Symbolic The Macroscopic Perspective =========================== - Physical changes - Chemical changes There are three phases of matter ================================ 1. Solids are hard and do not change their shapes easily at ordinary temperatures. 2. Liquids assume the shape of the portion of the container they fill. 3. Gases expand to occupy the entire volume of their containers.  ExampleProblem 1.1 ================== 1. water 2. hydrogen 3. oxygen The Symbolic Representation =========================== a. pure aluminum, Al b. aluminum oxide, Al2O3 - Particulate level representation for b. Particulate level representation for pure aluminum oxide, Al2O3, in bauxite. aluminum, Al. The Science of Chemistry: Observations and Models ================================================= Characteristics of Error ======================== 1. Random error --may make a measurement maybe too high or too low and is associated with the limitations of the equipment with which the measurement is made. 2. Systematic error -- makes measurements consistently either too high or too low. - Accuracy --indicates how close the observed value is to the "true" value - Precision - the spread in values obtained from measurements; it is the reproducibility of values  Measurements contain two types of errors ======================================== a. Random Error - may make a measurement randomly too high or too low (e.g., variation associated with equipment limitations) b. Systematic Error - may make a measurement consistently too high or too low (e.g., the presence of an impurity) - Inductive reasoning begins with a series of specific observations and attempts to generalize to a larger, more universal conclusion. - Deductive reasoning takes two or more statements or assertions and combines them so that a clear and irrefutable conclusion can be drawn. - They allow us to summarize a large number of observations concisely. - They allow us to predict behavior in circumstances that we haven't previously encountered. - They represent examples of creative thinking and problem solving - Constructing and refining models can lead to an ultimately more fundamental understanding of a problem. a. Prefixes - provide scale to a base unit b. Significant Figures - indicate the amount of information that is reliable when discussing a measurement -- -- -- -- - The base unit designates the type of quantity being measured. - SI units (from French *Système International d'Unités*) are the base units of science. - Some units comprise combinations of these base units and are termed derived units 1 J = 1 kg m^2^ s^-2^  Factor Symbol Factor Symbol -------- -- -------- -------- -- -------- 1024 Y 10-1 d 1021 Z 10-2 c 1018 E 10-3 m 1015 P 10-6 𝜇 1012 T 10-9 n 10^9^ G 10-12 p 10^6^ M 10-15 f ------- -- ---- ------- -- --- 10^3^ k 10-18 a 10^3^ h 10-21 z 10^1^ da 10-24 y A. All digits reported are considered significant except for certain types of zeros. a. When a zero establishes the decimal place, it is not significant. - 51,300 m (3 significant figures) - 0.043 g (2 significant figures) b. A zero is significant when it *follows* a decimal point or when it occurs between other significant figures. - 4.30 mL (3 significant figures) - 304.2 kg (4 significant figures) c. All numbers are significant when written in correct scientific notation. B. All digits reported are considered significant except for certain types of zeros. d. When a zero establishes the decimal place, it is not significant. - 51,300 m (3 significant figures) \-- 5.31 x 10^3^ - (2 significant figures) \-\-\-\-\-\-\-\-\-\-\-- 4.3 x 10^-2^ C. A zero is significant when it *follows* a decimal point or when it occurs between other significant figures. - 4.30 mL (3 significant figures) - 304.2 kg (4 significant figures) D. All numbers are significant when written in correct scientific notation. Example Problem 1.2 =================== 1. For [multiplication and division], the number of significant figures in a result must be the same as the number of significant figures in the factor with the [fewest] significant figures. 2. For [addition and subtraction], the number of significant figures is determined from the position of the [first uncertain digit]. Example Problem 1.3 =================== a. Calculations involving ratios b. Conceptual understanding of particulate level c. Visualization of phenomena on different levels 𝑃𝑟𝑖𝑐𝑒 = Example Problem 1.4 =================== Example Problem 1.5 =================== Ratios in Chemistry Calculations ================================ - Temperature- and compound-specific - Allows conversion between mass and volume. Example Problem 1.6 =================== PROBLEMS: ========= 1. Superconductors are materials that have no resistance to the flow of electricity, and they hold great promise in many engineering applications. But to date, superconductivity has only been observed under cryogenic conditions. The highest temperature at which superconductivity has been observed is 138 K. Convert this temperature to both °C and °F. 2. Express **(a)** 275°C in K, **(b)** 25.55 K in °C, **(c)** --47.0°C in °F, and **(d)** 100.0°F in K. 3. How many significant figures are there in each of the following? 4. Perform these calculations and express the result with the proper number of significant figures. 5. Carry out each of the following conversions: -- -- -- -- -- -- 6. If a vehicle is traveling 92 m/s what is its velocity in miles per hour? 7. Mercury has a density of 13.6 g/mL. What is the mass of 4.72 L of mercury? 8. The dimensions of aluminum foil in a box for sale in supermarkets are 3 9. Wire is often sold in pound spools according to the wire gauge number. That number refers to the diameter of the wire. How many meters are in a 10-lb. spool of 12-gauge aluminum wire? A 12- gauge wire has a diameter of 0.0808 in. and aluminum has a density of 2.70 g/cm^3^ 10. A load of asphalt weighs 254 lb.and occupies a volume of 220.0 L. What is the density of this asphalt in g/L?