|
1
|
|
|
2
|
- This chapter covers the following:
- Scientific Methods
- Measurements used in the laboratory
- Units, uncertainty, significant figures
- Handling numerical results
- Operational rules, unit Factor, …
- Classification of Matter
- Element, compound, mixture, …
|
|
3
|
- Chemistry is all around you all the time
- body, plants, cars, … etc.
- Chemistry is important to historians
- Dinosaurs disappearance ????? {meteor}.
- Decline of Roman Empire ?????? {lead poisoning}.
- Chemistry is important in determining a person’s behaviour
- Statesville Prison (Illinois) ŕ (violent) !!!!!!!!
- Insects communications (Pheromones) !!!!!!!!!!
|
|
4
|
- It is fundamentally concerned with:
- "How one substance changes to another"
- How plants grow by absorbing water and Carbon dioxide?
- How humans manufacture the proteins from the food we consume?
- ….. and on and on
|
|
5
|
- Water
- most common and important substance, is composed of two types of atoms,
Hydrogen and Oxygen.
|
|
6
|
- It is a systematic approach to research that includes:
- Define the problem
- Perform experiment and collect data
- Enough data may led to "Hypothesis"
|
|
7
|
- Quantitative Measurement, consists of two parts:
- a number and a scale (unit)
- In 1960, an international agreement get up a system of units called International
System (SI- system) based on metric system.
|
|
8
|
|
|
9
|
- Volume is not fundamental SI – unit, but very commonly used in
chemistry,
- {SI derived unit for volume is cubic meter (m3)}
|
|
10
|
- Any measurement always has some degree of uncertainty.
- Record the certain digits and the first uncertain digit only.
- [ certain + first uncertain]
- The total numbers of the digits are called
- " Significant Figures"
- e.g.,
|
|
11
|
- Random error:
- Systematic error:
|
|
12
|
- Rules for Counting Significant Figures:
- Nonzero integers are countable as SF.
- Zeros:
- - "Leading zeros” are not significant. e.g. 0.0025 (2 SF)
- - "Captive zeros”
Count as s.f. e.g.: 1.008 (4 SF)
- - "Trailing zeros” count as s.f. eg. : 100 = 1.00 X 102
(3 SF)
- Exact numbers have an infinite
number of SF
- e.g. 10 experiment, 5 apples, 8 books … so on. ..
- Exponential notation:
- it is used to express large or small numbers in the correct SF
- e.g. 0.000060 ŕconvenient ŕ 6.0 x 10-5
|
|
13
|
- Rules for SF in Mathematical Operations:
- Multiplication / Division: Final results have the same SF in the least
precise measurement used in calculation.
- Addition / Subtraction: Final results have the same number of decimal
places as the least precise numbers.
|
|
14
|
- conversion of a given results from one system unit to an other using
"Unit Factor Method" or dimensional analysis.
|
|
15
|
|
|
16
|
|
|
17
|
- Read (pp. 26-30)
- and Report (HW#2):
- Define :
- Matter,
- Mixtures,
- Physical changes,
- Chemical Changes,
- Compound,
- and Element
- Define:
- Distillation,
- Filtration,
- and Chromatography
|
|
18
|
|
Notes
