DLC 321C Chemistry A science for the 21st century health and medicine surgery with anesthesia vaccines and antibodies gene therapy energy and the environment The study of Chemistry Macroscopic Microscopic atoms molecules data we can collect and analyze big The scienti c method is a systematic approach to research observation representation interpretation A hypothesis is a tentative explanation for a set of observations tested modi ed A law is a concise statement of a relationship between phenomena that is always the same under the same conditions ex force max acceleration A theory is a unifying principle that explains a body of facts and or those laws that are based on them Matter is anything that occupies space and has mass a substance is a form of matter that has de nite composition and distinct properties slides posted online A mixture is a combination of two or more substances in which the substances retain their distinct identities homogenous same throughout heterogeneous not the same throughout Physical means can be used to separate a mixture into its pure components distillation An element is a substance that cannot be separated into simpler substances by chemical means 114 elements have been identi ed 82 elements occur naturally on earth A compound is a substance composed of atoms of two or more elements chemically united in xed proportions compounds can be separated into their pure components elements by chemical means separation mixture physical means compound chemical means A comparison the three states of matter solid liquid gas A physical change does not alter the composition or identity of a substance ice melting sugar dissolving in water A chemical change alters the composition or identity of the substance s involved Extensive and intensive properties An extensive property of a material depends upon how much matter is being considered An intensive property of a material does no depend upon how much matter is being considered Matter anything that occupies space and has mass mass measure of the quantity of matter SI unit of mass is the kilogram kg 1kg 1000g 1 10 3g weight force that gravity exerts on an object mass length volume density temperature color weight c x mass length meter m mass kilogram kg time second s 10 ml in 1 cm 1 cm in 1 millimeter 100 cm in 1 meter memorize pre xes used with SI units covert from meters into centimeters centimeters into decimeters on powerpoint volume SI derived unit for volume is cubic meter m 3 SI unit of volume is m 3 1 cm 10 2 meters Density SI derived unit for density is kg m 3 density mass volume d m v A comparison of Temperature Scales K C 273 15 273 15K 0C 373 15K 100 c 32 F 0 C 212 F 100 C Cant have negative kelvin Temperature Scales K C 273 15 C K 273 15 Scienti c Notation Addition Subtraction Multiplication Division Signi cant Figures Scienti c measurements are reported so that every digit is certain but the last one which is estimated The last digit is signi cant even though it is estimated To determine the number of signi cant gures in a number follow the following rules 1 All non zero digits are signi cant Ex 324 3 sig gs Ex 12 3 3 sig gs 2 Zeros between non zero numbers are signi cant Ex 301 3 sig gs 3 Leading zeros zeros to the left of the rst non zero number are not signi cant Ex 0 002 1 sig g Ex 0 0302 3 sig gs Ex 0 00101 3 sig gs 4 Trailing zeros zeros at the end of a number are categorized as follows 4 A Trailing zeros at the end of a decimal point are always signi cant Ex 0 200 3 sig gs 4 B Trailing zeros in a number not containing a decimal point are ambiguous and should be avoided using scienti c notation Ex 1200 ambiguous don t know if they are sig gs or not 1 2 10 3 2 sig gs 1 200 10 3 4 sig gs Exact numbers have unlimited numbers of signi cant gures 1 Accurate counting of discreet objects Ex 248 students unlimited sig gs 2 De ned quantities Ex 10 millimeters in 1 centimeter unlimited sig gs 3 Integral numbers that are part of an equation Ex The 2 has unlimited numbers of signi cant gures Rules for calculation 1 Multiplication Division The result carries the same number of signi cant gures as the quantity with the fewest signi cant gures Ex 1 052 12 054 0 53 6 7208 6 7 2 sig gs 2 Addition Subtraction The result carries the same number of decimal places as the quantity with the fewest number of decimal places Ex 2 345 0 07 2 9975 5 4125 5 41 Rounding Round down if the rst digit dropped is 4 or less Round up if the rst digit dropped is 5 or more Accuracy and Precision Accuracy How close the measurement is to the actual true value Precision How close they are to each other Ex Mass of a pen The true value is 5 40 g Set 1 First time 5 38 Second time 5 40 Set 2 Student 1 5 10 g Student 1 5 30 Dimensional Analysis Method in Solving Problems inch centimeter number increases small to big answer gets bigger Conversion from one unit to another Given quantity conversation factor desired quantity or Given unit desired unit given unit desired unit Example 1 in 2 54 cm 1in 2 54cm or 2 54cm 1in 1 Example convert 12 00 in into cm Convert 57 8 m into cm 1m 100cm He will give us the conversations such as 1 in whatevercm but we must remember the table of pre xes such as giga and milli Convert 5 2L into m 3 1L 1 000cm 3 1 liters cm 3 m 3 1 cm 0 01m A plane is fueled with 173 231L of jet fuel If the density of the fuel is 0 768g cm 3 what is the mass of the fuel in kilograms The density of titanium is 4 51g cm 3 What is the volume in cubic inches of 3 5 lb of tianium Scienti c Notation Addition Subtraction Multiplication Division Signi cant Figures Scienti c measurements are reported so that every digit is certain but the last one which is estimated The last digit is signi cant even though it is estimated To determine the number of signi cant gures in a number follow the following rules 1 All non zero digits are signi cant Ex 324 3 sig gs Ex 12 3 3 sig gs 2 Zeros between non zero numbers are signi cant Ex 301 3 sig gs 3 Leading zeros zeros to the left of the rst non zero number are not signi cant Ex 0 002 1 sig g Ex 0 0302 3 sig gs Ex 0 00101 3 sig gs 4 Trailing zeros zeros at the end of a number are categorized as follows 4 A Trailing zeros at the end of a decimal …
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