CHEM 130 Exam 1 (Chapters 1-3) Questions And Answers Well Elaborated

Chemistry - correct answers Science that seeks to understand the behavior of matter by studying the behavior of atoms and molecules; studies change of matter Microscopic level - correct answers atomic and molecular view Macroscopic level - correct answers lab view Structure and Properties: Same atom/molecule - correct answers Properties are different because structure form differently or are not the same Structures and Properties: Temperature - correct answers different structures at different temperatures "HOT" demonstration Clinical: Heart disease - correct answers fat deposit (plaque) is fixed with metal stent; starts at low temp.=normal wire; hearts have higher temp. so stent forms Scientific knowledge is empirical... - correct answers based on observations and experiments Scientific method purpose - correct answers process for understanding nature by observing in nature and its behavior, and by conducting experiments to test ideas SM 1) Observation - correct answers "data" SM 2) hypothesis - correct answers tentative interpretation of explanation of the observations good hypothesis=falsifiable SM 3) scientific law - correct answers brief statement that summarizes past observations and predicts futures ones; allows testing SM 4) theory - correct answers model for the way nature is and tries to explain why nature does what it does; validated by experiments SM 5) Further experiments - correct answers Continue studies Two unit systems - correct answers SI system & English system SI base units - correct answers m - Meter - Length. s - Second - Time. mol - Mole - Amount of Substance. A - Ampere - Electric Current. K - Kelvin - Temperature. cd - Candela - Luminous Intensity. kg - Kilogram - Mass. Absolute zero - correct answers K=0 K C=-273 F=-459 Temperature conversions - correct answers K=C+273.15 F=9/5(C)+32 C=5/9x(F-32) Prefixes used in SI - correct answers tera T ^12 giga G ^9 mega M ^6 kilo k 1000 10^3 hecto h 100 10^2 deca da 10 10^1 (none) (none) 1 100 deci d 0.1 10^−1 centi c 0.01 10^−2 milli m 0.001 10^−3 micro μ 0.^−6 nano n 0.000^−9 pico p 0.000000^−12 femto f 0.^−15 Derived unit - correct answers combo of two or more units Common derived units - correct answers 1L=1000mL=1cm^3 1mL=1cm^3 Density - correct answers ratio of a substance's mass to volume d=m/v g/cm^3 or g/L density of water= 1g/cm^3 Sig figs rules - correct answers 1) Zeros between other significant digits are significant example: 405=3; 807.105=6 2) Zeros on the right of the first non-zero digit are significant example: 0.03800=4; 3,6000,000=7 3) Zeros on the left of the first non-zero digit are not significant example: 0.006=1; 0.0352=3 4) Zeros on the right of the last non-zero digit, but to the right of the decimal are ambiguous, but can be clarified with scientific notation example: 47,000=2-5; 380=2-3; 1.00x10^7=3 Sig figs: Addition and subtraction - correct answers addition & subtraction: a sum of sigfigs will have no more digits to the right of the decimal than does any addend. That is, the sum is limited in its right-of-decimal digits by the number in the calculation with the fewest digits: Sig figs: multiplication and division - correct answers multiplication & division: the product will have no more sigfigs than any factor in the calculation, and the quotient not more than any divisor in the calculation (these exclude defined relations) Sig figs: Rounding off - correct answers 1) When the unwanted digits are more than 5, round up: (to 3 sigfigs) 2.45633-2.46 2) If the unwanted digits are less than 5, round down: (to 4 sigfigs) 37,913-37,910 or 3.791x104 3) If the unwanted digits are exactly 5: -if the last digit is odd, round up to the next even: (to 3 sigfigs) 23.3544-23.4 -if the digit is even, do nothing: (to 4 sigfigs) 0.-0.07236 4) Carry all of the figures through the calculation and round off to the appropriate number of sigfigs only at the very end to avoid "round off error." Accuracy - correct answers close to actual value Precision - correct answers close to each other Unit conversion - correct answers Dimensional analysis; EXAMPLES 1) find out given and required to find 2) find out equivalence relationship between the two 3) construct conversion factors 4) find out which conversion factor to use TRIAL AND ERROR Interconvertible units - correct answers g/mL mph 1 fs= 10^-15s g/mol J/m^2 Matter - correct answers anything that has mass and occupies space Solid - correct answers atoms or molecules packed close together in fixed locations no free move Liquid - correct answers atoms or molecules further apart than solid, but free to move free to move with little space Gas - correct answers atoms or molecules have a lot of space free to move and a lot of space Composition of matter - correct answers 1) connect to form atom 2) chemical bond to form molecule 3) intermolecular force (IMF) b/w substances 4) mixture Clinical: Iron seperation - correct answers Iron extracted from cereal; need iron in order to survive because it supplies O2