Right Side NOTES ONLY. TN Ch 2.1, 2.3 Topic: EQ:

Transcription

1 CH 2 MEASUREMENTS

2 Title and Highlight Right Side NOTES ONLY TN Ch 2.1, 2.3 Topic: EQ: Date Reflect Question: Reflect on the material by asking a question (its not suppose to be answered from notes) NOTES: Write out the notes from my website. Use different types of note-taking methods to help you recall info (different color pens/highlighters, bullets, etc) When I lecture we will add more info, so leave spaces in your notes Summary Questions: Write Book Question out and answer it (in another color based on what you read from my notes or textbook. THESE ARE AT THE VERY END OF NOTES

3 Title and Highlight LEFT Side PICTURES, PRACTICE PROBLEMS, ETC TN Ch 2.1, 2.3 DRAW ANY PICTURES, FIGURES, AND WRITE OUT ANY PRACTICE PROBLEMS/QUESTIONS. WE WILL ANSWER THEM TOGETHER. LEAVE SPACES SO WE CAN ANSWER QUES.

4 TN CH 2.1, 2.3 TOPIC: SIGNIFICANT FIGURES EQ: HOW DO YOU DETERMINE IF A NUMBER IS SIGNIFICANT? **READ Ch 2.3 (pg ) first then take notes**

5 2.1 MEASURING ITEMS A UNIT is a standard, agreed-on quantity by which other quantities are measured. The uncertainty is indicated by the last reported digit. Example: grams

6 CH 2.3 WRITING NUMBERS TO REFLECT PRECISION Scientific numbers are reported so that every digit is certain except the last, which is estimated.

7 SIGNIFICANT FIGURES: SIG FIG S (S.F.) The greater the precision of the measurement, the greater the number of significant figures!!! Determining s.f. s are fairly easy to determine. HOWEVER if the number contains a ZERO then we must determine if it is significant!

8 RULES FOR COUNTING SIGNIFICANT FIGURES Rule #1 - Nonzero integers always count as significant figures has 4 sig figs.

9 Rule #2 - Leading zeros do not count as significant figures has 3 sig figs. These ZERO s are called PLACEHOLDERS!

10 Rule #3 - Captive zeros always count as significant figures has 4 sig figs.

11 Rule #4 - Trailing zeros are significant only if the number contains a decimal point has 4 sig figs.

12 Left side PRACTICE PROBLEMS #1 How many significant figures in each of the following? a m b kg c. 100,890 L d x 10 3 s e cm f. 3,200,000

13 Left side How many significant figures are in each number? a b c d e. 1 dozen f g. 100,000 Practice Problems #2

14 Left side Determine the number of significant digits in the following numbers: x Practice Problems #3

15 RIGHT side - End of notes SUMMARY QUESTIONS: CH 2 #4-5 Number BQ and write it out Answer it (in another color/highlight it based on what you read from my notes or textbook)

16 Ch 2.4 Topic: PERFORMING CALCULATIONS USING SIG FIG S EQ: How do we determine how many Sig Fig s an answer in a calculation would have? **READ Ch 2.4 (pg ) first then take notes**

17 RULES FOR ADDING/SUBTRACTING SIG FIGS Addition and Subtraction: least places after the decimal between all the numbers you are adding or subtracting.

18 Left side PRACTICE PROBLEMS # =?? =?? =?? =??

19 RULES FOR MULTIPLYING/DIVIDING SIG FIGS Multiplication and Division: least # of sig figs between ALL numbers.

20 Left side PRACTICE PROBLEMS # x 0.12 x =?? =?? 1.10 x =?? x =??

21 SIG FIG S IN CALCULATIONS RULES FOR ROUNDING: For calculations involving multiple steps, round only the final answer do not round off between steps. This prevents errors in the final answer. Don t round if the last digit dropped is 4 or less Round up if the last digit dropped is 5 or more. Example: If you need only 3 s.f. s, then is 35.4 (don t round up) is 35.5 (round up)

22 CALCULATIONS INVOLVING BOTH MULTIPLICATION/DIVISION AND ADDITION/SUBTRACTION 1. Do parentheses first. 2. Determine the correct # of sig figs in the answer without rounding. 3. Then do the remaining steps. 4. Remember order of opp s: P.M.D.A.S. 5. ONLY look at final answer when determining to round

23 Left side PRACTICE PROBLEMS # x ( ) =?? 6.78 x x ( ) =?? (5.4 x 0.916) =??

24 RIGHT side - End of notes SUMMARY QUESTIONS: CH 2 #7-10 Number BQ and write it out Answer it (in another color/highlight it based on what you read from my notes or textbook)

25 CH 2.5 TOPIC: BASIC UNITS OF MEASUREMENT EQ: WHAT ARE THE DIFFERENT TYPE OF UNITS USED? **READ Ch 2.5 (pg ) first then take notes**

26 2 types of measuring systems: 1. English system (USA): Ex: inches, yards, pounds. 2. Metric system (most of the world): Ex: grams, meters, Liters

27 Every measurement must have a unit.

28 HIGHLIGHT PROBLEM (READ ONLY) In 1999, NASA lost a $94 million orbiter because two groups of engineers failed to communicate to each other the units that they used in their calculations. Consequently, the orbiter descended too far into the Martian atmosphere and burned up.

29 In 1795, scientist around the world came together to develop a unit system for science measurements, based on the metric system. Called the International System of units or SI units.

30 MASS VS. WEIGHT Mass depends on the amount of matter in the object. Weight depends on the force of gravity acting on the object. Weight may change as you move from one location to another; mass will not. You have the same mass on the moon as on the earth, but you weigh less since there is less gravity on the moon. Mass = 80 kg Weight = 176 lbs. Draw pic with notes Mass = 80 kg Weight = 29 lbs.

31 Left side

32 HOW TO WRITE UNITS 2 methods to write units: Base unit only (grams) Or Prefix + Baseunit = centigram = cg

33 Left side PRACTICE PROBLEMS #1 HOW TO WRITE UNITS cm = m = mm = L = dal = ml = g = kg = dg = s = ms =

34 WATCH VIDEO: (NRCHEMISTRY.WEEBLY.COM) Unit of Conversions!!

35 METRIC SYSTEM An easy way to move the decimal point one place for each step desired 5000 meters = millimeters If you move to the right in the diagram, move the decimal to the right kilo hecto deca meter liter gram deci centi milli kilo hecto deca 6700 centimeters = meters If you move to the left in the diagram, move the decimal to the left meter liter gram deci centi milli

36 Mount Everest is 8847 m high. How many centimeters & kilometers high is the mountain?

37 Left side Practice Problems #2: 380 km = m 1.45 mm = m 461 ml = dl 0.4 cg = dag 0.26 g = mg 230,000 m = km

38 RIGHT side - End of notes SUMMARY QUESTIONS: CH 2 #11, 12, 14 Number BQ and write it out Answer it (in another color/highlight it based on what you read from my notes or textbook)

39 CH 2.6 & 2.9 TOPIC: DENSITY EQ: HOW CAN YOU DETERMINE AN OBJECT S DENSITY? **READ Ch 2.6 & 2.9 (pg , 34-35) first then take notes**

40 Not all quantities can be measured with base units. A unit that is defined by a combination of units is called a derived unit. Two derived units are volume and density.

41 VOLUME Volume is the space occupied by an object. The derived unit for volume is the cubic centimeter (cm 3 ); used for solid objects. Liter (L) are used to measure the amount of liquids. For the smaller quantities, volume is measured in milliliters (ml). 1 ml = 1cm 3 ( this is how we can go from units of a solid to a liquid)

42 DENSITY Density is a ratio that compares the mass of an object to its volume The units for density: grams per cubic centimeter (g/cm 3 ) for solids grams per milliliter (g/ml) for liquids

43 DENSITY The density of an object will determine if it will float or sink in another phase. If an object floats, it is less dense than the other substance. If it sinks, it is more dense. The density of water is 1.0 g/ml m Density = m/v D X V Volume = m/d Mass = D x V

44 KNOW VS FIND CHART: HOW TO SHOW YOUR WORK Sort: Begin by sorting the information in the problem. (Know vs. Find) Units: Do not let units magically appear or disappear in calculations. Units must flow logically from beginning to end. Solve: Carry out calculation (pay attention to sig. fig. rules and cancel units as needed. Remember order of opp s: P.M.D.A.S. Know?? m = 44.7g Density V = 15.98mL

45 Left side Practice Problems #1: What is the volume of chemical sample that has a mass of 24 g and a density of 6.0 g/ml? Practice Problems #2: What is the density of 52g of Fe (iron) and that occupies 31.5 cm 3 of volume? Will this float or sink in water?

46 Left side Practice Problem #3: Densities are sometimes determined by water displacement Lab next week!!! An irregularly shaped piece of metal with a mass of 125g is placed into a graduated cylinder that contains 7.00mL of water. This raises the water level to 20.50mL. What is the density of the metal?

47 Left side Practice Problem #4: Calculate the mass of a block of iron (density = 7.86g/cm 3 ) with dimensions of 52.8cm x 6.74cm x 3.73cm.

48 Left side DENSITY S OF SUBSTANCES Table 2.4 provides a list of the densities of some common substances. This is useful when solving homework problems.

49 RIGHT side - End of notes SUMMARY QUESTIONS: CH 2 #17, 18, 29, 30 Number BQ and write it out Answer it (in another color/highlight it based on what you read from my notes or textbook)