Chem 1070 1st Edition Lecture 3 Outline of Last Lecture I. Conservation of MassII.States of MatterIII. Mixtures v. CompoundsIV. Physical and Chemical PropertiesOutline of Current Lecture II. Significant FiguresIII. Determining Sig Figs in an EquationIV. SI units and Unit ConversionsCurrent LectureSignificant FiguresAlso known as sig figs, they help us determine how many numbers you can have in your final answer for a problem. All non-zero digits are significant (i.e. 1-9). In a number without a decimal point, only zeros between non-zero digits are significant (i.e. . In a number with a decimal point, all zeros to the right of the first non-zero digits are significant ( i.e. 20.000 has 5 sig figs)Determining Significant Figures in an EquationWhen adding or subtracting you must determine significant figures based on the number with the least certainty. For instance if I was to add 12.3456 and 7.8, based on the rule for adding and subtracting I would only have a number in the tens place for the decimal because 7.8 has less certainty then 12.345 so my answer would be (without sig figs) 20.145. However with sig figs it would be 20.1When multiplying or dividing you must determine significant figures based on the total number of sig figs in each number and then use the least amount of sig figs. For example if I am multiplying 3 and 17 I would only have one sig fig in my answer because 3 has less sig figs than 17. In that case my answer without sig figs is 51 but with sig figs it is only 50 because 1 is less than 5 so you round down.SI Units and Unit ConversionsThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.The United States are one of the few countries that still use the metric system and not the SI system so we must make conversions to the SI system. Scientists usually record measurements in the SI system. Say if you had something in pounds (lbs) and you wanted to know how much it was in kilograms (kg), you would look up the unit conversion and see that one pound (1lbs) is equal to .4536 Kilograms (kg). So if you had a 20lbs child you would multiply 20 * .4536 = 9.072. However with sig figs it would just be 9kg because 20 only has 1 sig