TEMA PARA LA MATERIA DE QUÍMICA...t/t

1. MATTER AND
MEASUREMENT
QBA Miguel A. Castro Ramírez

2. THE STUDY OF CHEMISTRY
 Matter: Anything that has mass and takes up space.
 Atoms: The building blocks of matter.
 Property: Any characteristics that allows us to
recognize a particular type of matter and
to distinguish it from other types
 Elements: Substance that cannot be broken down
into simpler substances by chemical
rxns. E.g. O, N, C and P
: Made of the same kind of atom.
 Compound: Made of two or more
different kinds of elements.

3. CLASSIFICATION OF MATTER
1) PHYSICAL STATE (States of Matter)
GAS (Vapour) LIQUID SOLID
Observable Properties
 No fixed volume  Distinct volume  Definite volume
 Can be compressed to independent of container  Definite shape
occupy smaller volume  Shape depends on the  Cannot be compressed
 Can be expand to occupy container
larger volume  Cannot be compressed
Molecular Level
 Molecules are far apart  Molecules: Packed closely  Molecules: Tightly
 Speed : Very fast together but still move rapidly together
 Compressing: Decreases  The rapid movement  Definite arrangement
space increases frequency molecules to slide each  Can only wiggle each
of collisions but doesn’t alter other easy to pour other
the size/shape of the molecule

4. CLASSIFICATION OF MATTER
2) COMPOSITION
Pure Substances: Matter that has distinct properties and a composition that
does not vary from samples to samples
Element Mixture
- Cannot be Compound - Combination of two or
decomposed into - Subtances that more subtances in
simpler substances composed of 2 or which each subtances
- Composed only 1 kind retains its own
more different atoms
of atom chemically joined chemical identity
together

5. CLASSIFICATION OF MATTER
ELEMENTS COMPOUNDS MIXTURES
 The symbol of each  Elements can interact with  Each substance in a mixture
element consist of 2 letter, other elements to form retains its own chemical
with first letter capitalized compounds. identity and its own property.
e.g; C,Al,Br,Cu,Hg  H2 + O2  H2O  Composition of mixture can
 In periodic table of  H2O H2 + O2 be vary.
elements The observation that the  Components : Subtances
elemental composition of a making up mixture.
pure compound is always the  Homogeneous: Uniform
same: Law of Constant throughout e.g; Air-
Composition=Law of definite homogenuos mixture of
proportions gaseous subtances
Pure compound has the  Heterogeneous: Do not
same elements and have same composition,
composition & properties properties and appearance
regardless the source. throughout. E.g; rocks and
wood.

6. CLASSIFICATION OF MATTER

7. PROPERTIES OF MATTER
Physical Properties
- Those which the substance shows by itself without interacting with
another substance
- Melting point, boiling point, density
Chemical Properties
-Those which the substance shows as it interacts with, or transforms into,
other substances
- Such as flammability, corrosiveness
Intensive Properties
- Do not depend on the amount of the sample being examined
- Temperature, melting point and density
Extensive Properties
-Depends on the quantity of the sample with two examples being mass
and volume
- Mass and volume

8. PROPERTIES OF MATTER
Physical Changes
- Substances changes its physical appearance but not its composition.
- Changes of state (evaporation of water) , temperature, volume, etc.
Chemical Changes
- Substance is transformed into a chemically different substance
- Combustion, oxidation, decomposition, etc.

9. PROPERTIES OF MATTER
Separation of Mixtures
DISTILLATION CHROMATOGRAPHY
-Distillation uses -This technique separates
FILTRATION
-In filtration solid differences in the boiling substances on the basis of
points of substances to differences in solubility in
substances are
separate a homogeneous a solvent
separated from liquids
mixture into its - Test food colorings
and solutions.
components
- Separation of salt and
water

10. SCIENTIFIC METHOD
The scientific method is simply a systematic approach to solving
problems.
• Scientific Law: Concise verbal statement or a mathematical equation
that summarizes a broad variety of observations and experiences.
1. Hypothesis: tentative explanation/prediction concerning some
phenomenon. i.e. an educated guess that can be tested
2. Data: facts or measurements obtained through careful observation or
made during an experiment
3. Scientific laws: statements that identify patterns in a large collection of
data
4. Theory: Explains & predicts an observed phenomenon that can be further
tested

11. UNITS OF MEASUREMENT
 (SI) Système International d’Unités (International
System of Units)
 A different base unit is used for each quantity.
SI Base Units
1. Length – meter (m)*
2. Mass – kilogram (kg)*
3. Time – second (s)
4. Amount of substance – mole (mol)
5. Temperature – Kelvin (K)*
6. Electric current – Ampere (A)
7. Luminous intensity – candela (cd)
• All measured quantities can be expressed in terms of these 7
base units

12. UNITS OF MEASUREMENT (Metric System)
• Prefix used in metric system
• To indicate decimal fractions or multiples of various units
Multiple Decimal equivalent Prefix Symbol English
109 1,000,000,000 giga- G billion
106 1,000,000 mega- M million
103 1,000 kilo- k thousand
102 100 hecto- h hundred
101 10 deca- da ten
100 1 NA NA NA
10-1 0.1 deci- d tenth
10-2 0.01 centi- c hundredth
10-3 0.001 milli- m thousandth
10-6 0.000001 micro- µ (mu) millionth
10-9 0.000000001 nano- n billionth
10-12 0.000000000001 pico- p trillionth

13. UNITS OF MEASUREMENT
Length and Mass
- Unit SI for length = meter (m)
- Mass: Measure of the amount of material in an object.
- SI Unit= kilogram (kg) = 2.2 pounds (lb)
Temperature
- Measure of hotness or coldness of an object.
- Physical property: determine the direction of heat flow
- SI Unit: Kelvin (K): based on the property of gases
-Zero Kelvin= -273.15 °C – lowest attainable temperature
(absolute zero)
- The Celsius (°C) scale is based on the properties of water.
0°C = 273.15 K is the freezing point of water
100°C = 373.15 K is the boiling point of water
K= °C + 273.15
- Fahrenheit (°F) : Common in US (not generally used in scientific
studies)
°C = 5/9 (°F-32) or °F = 9/5 (°C) +32

14. UNITS OF MEASUREMENT
1) The temperature of the room is 75°F. What is its temperature in
Celsius degrees?
2) A child has a body temperature of 38.7°C.
a)If normal body temperature is 98.6°F, does the child have a
fever?
b)What is the child’s temperature in Kelvin?

15. UNITS OF MEASUREMENT
DERIVED SI UNITS
VOLUME
 Given by its length cubed, (length)3
 cm3 : Frequently used in chemistry
 Another commonly used metric units
for volume are the liter (L)
A liter (L) = dm3 = 1000mL
A milliliter (mm) = 1cm3
 Syringe, burets and pipets deliver
liquids with more precision than
graduated cylinders.

16. UNITS OF MEASUREMENT
DERIVED SI UNITS
DENSITY
 Property of matter that is widely used to characterize a substance.
 Density: mass/volume
 Expressed in unit g/cm3 or g/mL.
 Densities are temperature dependent – because most substances
change volume when they are heated or cooled.
 When reporting densities, temperature must be stated

17. UNITS OF MEASUREMENT
Calculating Density from Mass and Length
1) If a rectangular slab of Lithium (Li) has a mass of 1.49 x 10 3
mg and has sides that measure 20.9 mm by 11.1 mm by 11.9
mm, what is the density of Li in g/cm3 ?

18. UNCERTAINTY IN MEASUREMENT
Exact numbers: - Values are known exactly
- 12 eggs in a dozen, 1000g in 1kg
Inexact numbers: - Values have some uncertainty
- Obtained by measurement
- equipment and human errors
Uncertainties always exist in measured quantities
PRECISION AND ACCURACY
Accuracy : How closely individual measurements
agree with the correct or true value.
Precision : Measure of how closely individual
measurement agree with one another.

19. UNCERTAINTY IN MEASUREMENT
Significant Figures
Rules for counting sig figs
1. Nonzero integers always count as sig figs
2. There are 3 classes of zeroes:
a. Leading zeroes are zeroes that precede all the
nonzero digits. These DO NOT count as sig fig. e.g.
0.0025
b. Captive zeroes are zeroes b/w nonzero digits.
These ALWAYS count. E.g. 1.006
c. Trailing zeroes are zeroes at the right end of the
number. They are significant ONLY IF the number
contains a decimal point. E.g. 1.00

20. UNCERTAINTY IN MEASUREMENT
Rules of Significant Figures in Calculation
• When addition or subtraction is performed, answers are
rounded to the least significant decimal place.
12.11 +18.0 +1.013 = 31.123  to →31.1
 
corrected
• When multiplication or division is performed, answers are
rounded to the number of digits that corresponds to the
least number of significant figures in any of the numbers
used in the calculation.
4.56 x 1.4 =6.38   → .4
  6
corrected to
• BODMAS still applies – Bracket, Of, Division, Multiplication,
Addition, Subtraction

21. UNCERTAINTY IN MEASUREMENT
Determining the Number of Significant Figures
How many sig. fig in the given numbers below:
(a) 0.1044 g
(b) 0.0000007160 cm3
Determine the number of sig fig in the problem below:
(a) 9.2 cm x 6.8 cm x 0.3744 cm
(b) 865.9 – 2.8121

22. UNCERTAINTY IN MEASUREMENT
Dimensional Analysis
• We use dimensional analysis to
convert one quantity to
another.
• Most commonly dimensional
analysis utilizes conversion
factors (e.g., 1 in. = 2.54 cm)
1 in. 2.54 cm
or
2.54 cm 1 in.

23. UNCERTAINTY IN MEASUREMENT
Use the form of the conversion factor that puts
the sought-for unit in the numerator.
desired unit
Given unit × = desired unit
given unit
• For example, to convert 8.00 m to inches,
– convert m to cm
– convert cm to in.
100 cm 1 in.
8.00 m × × = 315 in.
1m 2.54 cm

24. UNCERTAINTY IN MEASUREMENT
Converting Units of Length
a) To wire your stereo equipment, you need 325 centimeters (cm) of
speaker wire that sells for RM 0.15/ft. What is the price of the wire?
- 1 in = 2.54 cm 1ft = 12 in
SOLUTION:
Length (in) = length (cm) x conversion factor
= 325 cm x in = 128 in
2.54 cm
Length (ft) = length (in) x conversion factor
= 128 in x ft = 10.7 ft
12 in
Price ($) = length (ft) x conversion factor
= 10.7 ft x RM 0.15 = $1.60
ft

25. UNCERTAINTY IN MEASUREMENT
Converting Units of Volume
When a small piece of galena, an ore of lead, is submerged in the
water of a graduated cylinder that originally reads 19.9 mL, the
volume increases to 24.5 mL. What is the volume of the piece of
galena in cm3 and in L?
volume (mL) before and after addition
subtract
volume (mL) of galena
1 mL = 1 cm3 1 mL = 10-3 L
volume (cm3) of volume (L) of
galena galena
SOLUTION: (24.5 - 19.9) mL = volume of galena = 4.6 mL
4.6 mL x 1 cm 4.6 mL x 10 L
3 -3
= 4.6 cm 3 = 4.6x10-3 L
mL mL

26. Thank You