1. Measurements and Calculations

2.  All measurements have a number part (quantitative) and a units part (qualitative)  7 cm  27.2 in  300 calories  Notice the difference in the numbers.  ALWAYS WRITE THE UNITS

3.  A system of measurement agreed on by scientist all over the world ◦ However, the US is the only country to continue to use their own measuring system (lbs, miles, cups, etc…)  There are 7 SI base units ◦ Look on page 34 Table 1  Prefixes added to the names of the SI units are used to represent quantities smaller or larger than the base unit ◦ Look on page 35 Table 2

4.  Mass is the amount of matter in an object ◦ Use a balance to measure  Weight is the measure of the gravitational pull on matter. It changes based on gravity. ◦ Use a spring scale to measure People often get these confused because weight is often expressed in grams

5.  The weight of a silver dollar  The length of a football field  The size of a farm  The thickness of a dime  The temperature of an oven  The depth of a lake  The width of a ski  The temperature outside

6.  A combination of SI Units ◦ Look on page 36 at Table 3  Volume-the amount of space occupied by an object ◦ Solids= m 3 ◦ Liquids & Gases= liters In chemistry, the most objects are too small to uses these units. Scientist use cm 3 and mL for most volume measurements. ***1 cm 3 = 1 mL

7.  Density= mass/volume  Units ◦ SI= kg/m 3 ◦ Scientist= g/mL or g/cm 3  Intensive Physical Property ◦ Doesn’t depend on amount ◦ Can be used to identify the object.  Density is dependant on temperature. Most objects’ density will decrease as the temperature gets larger.  Look on page 38 Table 2 ◦ Those with a smaller density will float in substance with a larger density. ◦ Those with a larger density will sink in a substance with a smaller density.

8.  Calculate the density with units ◦ 35.0 g occupies 25.0 mL ◦ 2.75 kg occupies 175 cm 3 ◦ 2.80 g occupies 2.00 L

9. 1. Calculate the volume that 35.2 g of carbon tetrachloride will occupy if it has a density of 1.6 g/cm 3 2. The density of ethanol is 0.789 g/mL. What is the mass of 150 mL? 3. A block of lead measures 2.000 cm x 3.000 cm x 4.500 cm. What is the mass of the block if the density of lead is 11.34 g/mL?

10.  q = mc  t ◦ q is the quantity of heat in Joules ◦ m is the mass in grams ◦ c is the specific heat (intensive physical property like density) measured in J/g o C ◦  t is the change in temperature (subtract two temperatures) ◦ Heat in = Heat Out ***Law of conservation of Energy

11.  How much heat is required to raise the temperature of 14.0 g lead (c = 0.1276 J/g o C) from 22 o C to 95 o C?  How much heat is needed to raise the temperature of 15 g of water (c = 4.184 J/g o C) from 22 o C to 95 o C?

12.  A piece of unknown metal with mass 14.9 g is heated to 100.0 o C and dropped in 75.0 g of water at 20.0 o C. The final temperature of the system is 28.5 o C. What is the specific heat of the metal?

13.  Page 42  Numbers 1, 2, 5

14.  Would you be breaking the speed limit in a 40 mi/h zone if you were traveling 60 km/h?  How can we compare the two if our units are not the same?

15.  We are going to create conversion factors and use the dimensional analysis (factor label method)  I know this sounds scary, but it isn’t that bad. We are just going to cancel out units!!!

16.  Some of these you may can do in your head, but show the factor label method.  Also, there may be one conversion factor.  How many quarters are in 5 dollars?  How many seconds are in one day?

17.  Convert 0. 75 kg to mg  Convert 1500 mm to km  Convert 750 micrograms to grams  Convert 25 miles to km  Convert 3.20 m to inches  Convert 5 lb to grams

18.  Would you be breaking the speed limit in a 40 mi/h zone if you were traveling 60 km/h?

19.  55 mi / hr to km / s  13.2 g / mL to oz / qt

20.  Page 42  Numbers 3, 4, 6

21.  35 mL to dL  950 g to kg  275 mm to cm  1,000 L to kL  1,000 mL to L  4,500 mg to g  25 cm to mm  0.005 kg to dag  0.075 m to cm  15 g to mg

22.  Accuracy and Precision ◦ Accuracy-how close to the correct or accepted value ◦ Precision-closeness of the numbers measured made in the same way (Has nothing to do with correct answer)  Percent Error ◦ (Value experimental - Value accepted ) / Value accepted then X 100 ◦ Look at practice problems on page 45

23.  There will always be some form of error in measurement.  Some include +- in their answer to express uncertainity

24.  The accuracy of the measurements taken and are dependent of the instrument used to measure them.  The digits allowed in an answer can imply no more accuracy than the “worst” measurement taken.

25.  All numbers 1-9 are significant ALWAYS  Zeroes ◦ 0 between digits are significant ALWAYS (107 = 3SD) ◦ 0 before any digits are NEVER significant (0.005 = 1SD) ◦ 0 at the end  NEVER without a decimal (2000 = 1 SD)  ALWAYS with a decimal (2000.0 = 5 SD)

26.  2420  0.0025  1.200  1020  0.005 800 (your book uses a space in long decimal numbers)  2000  What if 2000 needed to have 4 SD?

27.  If the number 2000 was an exact number, put it in scientific notation….  2.000 x 10 3 for 4 SD  2.00 x 10 3 for 3 SD  2.0 x 10 3 for 2 SD  + exponents indicate large numbers  - exponents indicate small numbers

28.  Line of numbers with decimal.  Round to the least # of significant decimal places.  135.6 g + 2.85 g (How many decimal places?)  250 mi – 14.87 mi (Round to which place value?)  Don’t forget your units of measure!

29.  Rounding 5 (EXACTLY) doesn’t always round UP!  To round EXACTLY 5-----Round EVEN  250 – 15 = 235 Final answer = 240  250 – 25 = 225 Final answer = 220  To see why---average your answers.

30.  Because the decimal moves, we will round to the LEAST # of SD  2.888 cm* 0.086 cm =  500 g / 0.1247 m =  24.0 km / 13468 s =  40.0 m* 2.0 m =

31.  16.5 cm + 8 cm + 4.37 cm =  350.0 m – 200 m =  6.54 m * 0.37 m =  39 cm 2 / 24.2 cm =

32.  Direct proportional ◦ Forms a straight line  Inverse Proportions ◦ Forms a curve

33.  Page 57  1-10

34.  Page 59-61  1, 4-5, 8-9, 11-14, 16-23, 25, 27, 35, 37- 44  ***Do this by yourself. This is a great test review.