Presentation on theme: "Equipment Scavenger Hunt Answers on my CP Chem page (on my website!)"— Presentation transcript:
1Measurement and Precision NOTES You need your clicker (from the 1st Day)
2Equipment Scavenger Hunt Answers on my CP Chem page (on my website!)
3Accuracy vs. PrecisionAccuracy is how close your measurement is to the actual or accepted value.Precision is the degree of “exactness” of a set of measurements – something you can repeat the same way again and again. Also, a number with more significant figures is more precise than one with less.
4accurate (the average is accurate) not precise precise not accurateaccurate and precise
5The Basic Rules of Sig. Figs! NONzero Numbers are ALWAYS significant!(ex. ( !)2. ZEROs within other nonzero numbers ARE sig.(ex all are significant!)3. Zeros that are PLACE HOLDERS are NOT significant! ( or 50000)*However a decimal shows precision (50000.)We will use the DOT RIGHT, NOT LEFT method.
6When using or averaging a set of numbers, the final answer can only be as precise as THE LEAST precise number!!!!!Look for the number that is the least precise and round the answer to the same number of digits.For addition and subtraction: Line up the numbers and round to the last decimal place of the least precise number.Add the following set and round the answer to the correct number of places , , 15.2,For multiplication and division: Round the final answer to the same NUMBER of SIGNIFICANT FIGURES as the number of sig. fig.s in the least precise measurement.Example: x2001 = 100 (only 1 S.F.)
7What is the most commonly used SI unit/units for the following? Mass – g (kg for physics)Length – mVolume – L (usually ml for chem)Density – g/ml or g/cc
8Kilo- hecta- deka- X deci- centi- milli- micro- How to Convert????The easy way: 1. Write down the scale or use the print out of the entire scale.Kilo- hecta- deka- X deci- centi- milli- micro-K h da base unit d c m µ(3 dec. places)Try 1g µg2. Find out what unit you have. (grams)3. Count the # of spaces you need to move.4. Figure out what direction to go.
9The metric system is based on multiples of 100. TrueFalseResponse Grid
10What is 5.0121 rounded to the hundredths place? None of theseResponse Grid
11What is 5.0121 rounded to the tenths place? None of theseResponse Grid
12What is 152,251 rounded to the hundreds place? 152,000152,250152,300Response Grid
13What is 152,251 rounded to the thousands place? 152,000152,250152,300Response Grid
14How many milliliters are there in a Liter? 1101001000Response Grid
15The measurement 20.00 grams is more precise than 20 grams. TrueFalseResponse Grid
16Which of the following best describes the length of the beetle's body in the picture? 1 to 2cm1.5 to 1.6cm1.54 to 1.56cm1.546 to 1.547cmResponse Grid
17If the black lines in the picture at left just touch the rim of the penny, which of the following best describes the penny's diameter?1 to 21.9 to 2.0cm1.92 to 1.94cm1.935 to cmResponse Grid
18What can you estimate from the left ruler? 1-2 in1.5 in1.45 in1.450inResponse Grid
19What can you estimate from the RIGHT ruler? 1-2 in1.5 in1.45 in1.450inResponse Grid
20Levi collects the following measurements: 50. 33g, 50. 32g, 50 Levi collects the following measurements: g, g, g The actual accepted value is grams, what can we say about his data?It is precise and accurate.It is precise, but not accurate.It is accurate, but not precise.
21Katie collects the following measurements: 55. 63g, 55. 62g, 55 Katie collects the following measurements: g, g, g The actual accepted value is grams, what can we say about her data?It is precise and accurate.It is precise, but not accurate.It is accurate, but not precise.
22These two are equivalent: These two are equivalent: km in 230m and equal in number of significant digits.TrueFalse
23Which number has 4 significant figures? 1.001020100.1000.B and D
24Bob is going to run 5km. This is the same as running 5000m. TrueFalse
25Which number has the most significant figures? 101001000They all have the same # of sig. figs