CHEM 161 Lecture Compiled Question & Answers Latest Updated and Approved

What is the difference between an intensive and extensive property? What are examples of each? Intensive properties, like density, don’t depend on the amount of matter. They are useful in describing and identifying a substance. Besides density, other intensive properties are MP and BP. Extensive properties would be mass or volume because they are different for each size of sample. How do sfs dictate certainty? The more sfs there are, the more precise your value is How many sfs are there in 0.0540? 3 – trailing zeroes after a dc pt are sig Why do we write numbers in scientific notation when we get large numbers (think sig figs) trailing zeroes before an implied dc pt are AMBIGUOUS and scientific notation should be used instead (4000) 4 x10^3 = uncertainty +1000 ( range) 4.0 x 10^3 = +(100) 4.00 x 10^3 = +10 4.000 x 10^3 = +1 (10.6-0.911)/(1.11)(0.3240) First, 10.6 – 0.911 = 9.689 (2 sf) = 9.7 (don’t round yet tho in ur answer. just know there’s two sfs) Next, divide 9.689/ (1.11 3sf) (0.3440 4 sfs) = 26.94083 round to 2 sfs 27 What’s the difference between a physical and chemical property? A physical property is something that can be observed or measured without changing the composition of matter What is the difference between accuracy and precision? Accuracy refers to how close the measured value is to the actual value. Precision refers to how close a series of measurements are to each other. What kind of error persists with low accuracy and precision? Random Error – error that has equal probability of being too high or too low. Usually averages out with repeated trials.