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- Professor Abdul Muttaleb Jaber
- Chemistry Department
- Office: Room # 261F
- Tel: 2611
- E-mail: amjaber@kfupm.edu.sa
- Office hours: S 9-10; 11-12 am
- U 9-10 am
- M 9-10; 11-12 am
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- An overview
- The scientific method
- Units of measurements
- Uncertainty in measurements
- Significant figures and
- calculations
- Dimensional analysis
- Temperature
- Density
- Classification of matter
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- Matter is composed of atoms
- Atoms are found as individuals or molecules
- Atoms and molecules are connected by electrons
- The challenge of chemistry is to think of the material the atomic level
- 100 different types of atoms form all substances in the world
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- Matter is composed of various types of atoms or molecules.
- Water is composed of O and H; H2O
- An electric spark causes a mixture of O2 and H2 to
explode forming H2O.
- One substance changes to another by
- reorganizing the way atoms
attached to each other
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- It is a way of solving problems
- It consists of the following steps:
- Observation- what is seen or measured
- Hypothesis- guess of why things behave the way they do. (possible
explanation for an observation)
- Experiment- designed to test hypothesis
- These steps would lead to new observations, and the cycle goes on
- Once a set of hypotheses agree with
- observations, they are grouped
into a theory
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- Thery is a set of tested
hypothesis that gives an overall explanation for a natural phenomenon
- Laws are summaries of observations
- Often mathematical
relationship
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- Every measurement has two parts
- Number
- Scale (called a unit)
- SI system (le Systeme International in French) based on the metric
system
- Examples:
- 20 grams
- 20 k g
= 20 X103 g
- 20 m g
= 20 X10-3 g
- 6.63 ´ 10-34 Joule seconds
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- Fundamental SI base Units
- Mass - kilogram (kg)
- Length- meter (m)
- Time - second (s)
- Temperature- Kelvin (K)
- Electric current- ampere (amp, A)
- Amount of substance- mole (mol)
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- giga- G 1,000,000,000 109
- mega - M 1,000,000 106
- kilo - k 1,000 103
- deci- d 0.1 10-1
- centi- c 0.01 10-2
- milli- m 0.001 10-3
- micro- m 0.000001 10-6
- nano- n 0.000000001 10-9
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- Liter is defined as the volume of 1 dm3
- 1 dm3 =
- (10cm)3 =
- 1000 cm3 =
- 1000mL
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- Mass is measure of resistance to change in motion
- Weight is force of gravity.
- Sometimes used interchangeably
- Mass can’t change, weight can
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- Random Error (Indeterminate Error) - measurement has an equal
probability of being high or low.
- Systematic Error (Determinate Error) - Occurs in the same direction each
time (high or low), often resulting from poor technique of measurement
or bad equipment.
- You can have precision without accuracy
- You can’t have accuracy without precision (unless you’re really lucky).
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- A measurement always has
- some degree of uncertainty.
- Uncertainty has to be indicated
in any measurement.
- Any measurement has certain
digits and one uncertain digit.
- A digit that must be estimated is
- called uncertain.
- The number of certain digits +
the uncertain digit is called number of significant figures.
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- Accuracy: Agreement of a
particular value to the true value (degree of correctness)
- Measurements that are close to the “correct” value are accurate.
- Precision: The degree of agreement among several measurements of the
same quantity (degree of repeatability).
- Measurements that are close to each other are precise.
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- For multiplication and division
- the results are reported to the least number of significant figures
- 354.760 X 0.0004567 = 0.162018892
- = 0.1620
- For addition and subtraction
- The results are reported to the least number of decimal places
- 345.672 – 34.56720 = 311.1048
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= 311.105
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- Nonzero integers always count as significant figures.
- 3456 has
- 4 sig
figs.
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- Zeros
- Leading zeros do not count as significant figures.
- (Zeros before the nonzero
digit)
- 0.0486 has
- 3 sig figs.
- 0.0003 has
- one significant figure
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- Zeros
- Trailing zeros are significant only
- if the number contains a decimal point.
- 9.300 has
- 4 sig figs.
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- Exact numbers have an infinite number of significant
figures.
- 1 inch =
2.54 cm, exactly
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- To get the correct number of significant digits
- you need to round numbers
- In a series of calculations get one extra digit then
- round
- If the digit to be removed
- is less than 5, the preceding digit stays the same
- is equal to or greater than 5, the preceding digit is increased by 1
- Don’t forget to add place-holding zeros if necessary to keep value the
same!!
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- 2.54 X 0.0028 =
- 0.0105 X 0.060
- 1) 11.3 2) 11
3) 0.041
- Continuous calculator operation =
- 2.54 x 0.0028 ¸
0.0105 ¸ 0.060
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- Here, the mathematical operation requires that we apply the addition/
subtraction rule first, then apply the multiplication/division rule.
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- Using the units to solve problems
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- Initial unit
- 2.5 hr
- Conversion Final
- factor unit
- 2.5 hr x 60 min = 150 min
- 1 hr
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- How many seconds are in 1.4 days?
- Unit plan: days hr min seconds
- 1.4 days x 24 hr x
??
- 1 day
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- The speed limit is 65 mi/hr. What is this in m/s?
- 1 mile = 1760 yds
- 1 meter = 1.094 yds
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- Initial
- 8450 ft x 12 in. x
2.54 cm x
1 m
- 1 ft 1 in. 100 cm
- x 1 min x
60 sec = 2400 sec
- 65 m 1 min
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- Define the three temperature
scales: Celsius , Fahrenheit and Kelvin
- Perform conversion from one to another.
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- Fahrenheit Celsius
Kelvin
- Water boils 212°F 100°C 373 K
- 180° 100°C 100K
- Water freezes 32°F 0°C 273 K
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- Density is the mass of substance
- per unit volume of the substance:
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- An empty container weighs 121.3 g. When filled with a liquid (density
1.53 g/cm3 ) the container weighs 283.2 g. What is the volume
of the container?
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- Matter: Anything occupying space
and having mass.
- Three States of Matter:
- Solid: rigid - fixed volume and
shape
- Liquid: definite volume but
assumes the shape of its container
- Gas: no fixed volume or shape - assumes
the shape of its container
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- Matter could be pure (one
component only) or mixture
- Mixtures have variable
composition (more than one component)
- A homogeneous mixture has visibly indistinguishable components usually
called a solution (for example, tap water)
- A heterogeneous mixture has visibly distinguishable components, clearly
not uniform (for example milk)
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- Element: A substance that cannot be decomposed into simpler
substances by chemical means.
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