1. Scientific Measurements

2. Scientific Notation In science, we deal with some very LARGE numbers:
1 mole =
In science, we deal with some very SMALL numbers:
Mass of an electron = kg

3. Imagine the difficulty of calculating the mass of 1 mole of electrons!kg x
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4. Scientific Notation:
A method of representing very large or very small numbers in the form:
M x 10n
M is a number between 1 and 10
n is an integer

5. . 9 8 7 6 5 4 3 2 1
Step #1: Insert an understood decimal point
Step #2: Decide where the decimal must end
up so that one number is to its left
Step #3: Count how many places you bounce
the decimal point
Step #4: Re-write in the form M x 10n

6. 2.5 x 109
The exponent is the number of places we moved the decimal.

7. 0.0000579 1 2 3 4 5 Step #2: Decide where the decimal must end
up so that one number is to its left
Step #3: Count how many places you bounce
the decimal point
Step #4: Re-write in the form M x 10n

8. 5.79 x 10-5
The exponent is negative because the number we started with was less than 1.

9. Write the following in scientific notation:
4,100,000 = _______________
345,600,000,000 = _________
0.0456= ________________
=____________
O.00305= ____________
4.1 x 106
3.456 x 1011
4.56 x 10-2
1.2 x 10-7
3.05 x 10-3

10. Write the following in standard form:
4.67 x 103 =__________________
3.112 x 105 = _________________
3.112 x 10-4 = ________________
4 x 10-6 = ___________________
1 x 1011 = __________________
4670
311200
100,000,000,000

11. Metric Prefixes Kilo = 1000 Hecto = 100 Deka = 10 Deci = 1/10
Centi = 1/100
Milli = 1/1000

12. How Big? A meter is about 39 inches A kilometer is 0.62 mile
A centimeter is about the width of your little finger
A gram is about the mass of a paper clip
A kilogram is 2.2 pounds
2 liters (pop)

13. K H D O D C M
Changing from one metric unit to another is called metric conversion
“O” is the space where meter, liter, or gram belongs
Kids Have Dropped Over Dead Converting Metrics

14. K H D O D C M
To change from one metric unit to another, we simply move the decimal point.
For example:
25.4 km = _____________ cm?
K-H-D-O-D-C is 5 places to the right
25.4 km = 2,540,000 cm
You always need a number and a unit!

15. K H D O D C M 30 cm = ___________hm
C – D- O –D- H is 4 places to the left
30 cm = hm
(this is the same as hm)
14 dal = _____dl
D- O –D is 2 places to the right
14 dal = 1400 dl

16. SI Units Quantity Base Unit Symbol Length meter m Mass kilogram kg
Time
second s
Temp
kelvin K
Current
ampere A

17. SI Units Prefix Symbol Factor mega- M 106 kilo- k 103 deci- d 10-1
centi- c
10-2
milli- m
10-3
micro- 
10-6
nano- n
10-9
pico- p
10-12

18. Other metric units
Temperature is measured in degrees celsius or centigrade
Heat is measured in calories or joules
Weight is measured in newtons
Mega = 1,ooo,ooo
Micro = one millionth
Nano = one billionth

19. Reading the Meniscus
Always read volume from the bottom of the meniscus. The meniscus is the curved surface of a liquid in a narrow cylindrical container.

20. Try to avoid parallax errors.
Parallax errors arise when a meniscus or needle is viewed from an angle rather than from straight-on at eye level.
Incorrect: viewing the meniscus from an angle
Correct: Viewing the meniscus at eye level

21. Graduated Cylinders
The glass cylinder has etched marks to indicate volumes, a pouring lip, and quite often, a plastic bumper to prevent breakage.

22. Measuring Volume
Determine the volume contained in a graduated cylinder by reading the bottom of the meniscus at eye level.
Read the volume using all certain digits and one uncertain digit.
Certain digits are determined from the calibration marks on the cylinder.
The uncertain digit (the last digit of the reading) is estimated.

23. Use the graduations to find all certain digits
There are two unlabeled graduations below the meniscus, and each graduation represents 1 mL, so the certain digits of the reading are…
52 mL.

24. Estimate the uncertain digit and take a reading
The meniscus is about eight tenths of the way to the next graduation, so the final digit in the reading is
0.8 mL
The volume in the graduated cylinder is
52.8 mL.

25. 10 mL Graduate
What is the volume of liquid in the graduate? 6
_ . _ _ mL 6 2

26. 25mL graduated cylinder 1 _ _ . _ mL 1 5
What is the volume of liquid in the graduate? 1
_ _ . _ mL 1 5

27. 100mL graduated cylinder 5 _ _ . _ mL 2 7
What is the volume of liquid in the graduate? 5
_ _ . _ mL 2 7

28. The cylinder contains:
Self Test
Examine the meniscus below and determine the volume of liquid contained in the graduated cylinder.
The cylinder contains: 7
_ _ . _ mL 6

29. The Thermometer
Determine the temperature by reading the scale on the thermometer at eye level.
Read the temperature by using all certain digits and one uncertain digit.
Certain digits are determined from the calibration marks on the thermometer.
The uncertain digit (the last digit of the reading) is estimated.
On most thermometers encountered in a general chemistry lab, the tenths place is the uncertain digit.

30. Do not allow the tip to touch the walls or the bottom of the flask.
If the thermometer bulb touches the flask, the temperature of the glass will be measured instead of the temperature of the solution. Readings may be incorrect, particularly if the flask is on a hotplate or in an ice bath.

31. Reading the Thermometer
Determine the readings as shown below on Celsius thermometers:
_ _ . _ C 8 7 4
_ _ . _ C 3 5

32. Measuring Mass - The Beam Balance
Our balances have 4 beams – the uncertain digit is the thousandths place ( _ _ _ . _ _ X)

33. Balance Rules and zeroed before using it.
In order to protect the balances and ensure accurate results, a number of rules should be followed:
Always check that the balance is level
and zeroed before using it.
Never weigh directly on the balance
pan. Always use a piece of weighing
paper to protect it.
Do not weigh hot or cold objects.
Clean up any spills around the balance
immediately.

34. Mass and Significant Figures
Determine the mass by reading the riders on the beams at eye level.
Read the mass by using all certain digits and one uncertain digit.
The uncertain digit (the last digit of the reading) is estimated.
On our balances, the thousandths place is uncertain.

35. Determining Mass 1. Place object on pan
2. Move riders along beam, starting with the largest, until the pointer is at the zero mark

36. Check to see that the balance scale is at zero

37. 1 1 4
? ? ?
_ _ _ . _ _ _
Read Mass

38. 1 1 4 4 9 7
_ _ _ . _ _ _

39. M V D = Derived Units Volume – Amount of space occupied by an object.
* length  length  length
* (L X W X H)
Density - mass ÷ volume (g/cm3)
Example: Mass = 10g
Volume = 2 cm3
D = M V

40. Density V = 825 cm3 M = DV D = 13.6 g/cm3 M = (13.6 g/cm3)(825cm3)
An object has a volume of 825 cm3 and a density of 13.6 g/cm3. Find its mass.
GIVEN:
V = 825 cm3
D = 13.6 g/cm3
M = ?
WORK:
M = DV
M = (13.6 g/cm3)(825cm3)
M = 11,220 g

41. Dimensional Analysis The “Factor-Label” Method
Units, or “labels” are canceled, or “factored” out

42. Density D = 0.87 g/mL V = ? M = 25 g V = M D V = 25g 0.87 g/mL
1) A liquid has a density of 0.87 g/mL. What volume is occupied by 25 g of the liquid?
GIVEN:
D = 0.87 g/mL
V = ?
M = 25 g
WORK:
V = M D
V = g
0.87 g/mL
V = 28.7 mL

43. Density M = 620 g D = M V = 753 cm3 D = ? D = 620 g 753 cm3
2) You have a sample with a mass of 620 g & a volume of 753 cm3. Find density.
GIVEN:
M = 620 g
V = 753 cm3
D = ?
WORK:
D = M V
D = g
753 cm3
D = 0.82 g/cm3

44. Creating Graphs

45. Line Graphs Shows the relationship between 2 variables
Dependent Variable
Independent Variable

46. Bar Graphs
Useful for comparing information collected by counting

47. Circle Graphs
Circle graphs or pie graphs, shows how a whole quantity is broken down into parts.