C
Conservation of Matter
ti f M tt
43.43 g Original mass = 43.43 g Final mass
reactants
=
product
Transformation
y
All matter has the ability to transform, y
y
ie. Change
There are 3 types of transformations
1.
2.
3.
Physical
Ph
i l
Chemical
Nuclear
l
Transformations
y Physical: does not modify the nature, or the characteristic properties of the matter. The atom and the molecule does not change.
the molecule does not change
y Chemical: does modify the nature and the characteristic properties of the matter implies a characteristic properties of the matter, implies a rearrangement of the connections between atoms and the formation of new molecules. y Nuclear: implies a rearrangement of particles in the nucleus and the formation of new elements
Chemical Transformation
y The bonds between the atoms (reactants) will break and new bonds will form elsewhere ( products).
y How to recognize a chemical transformation?
H i h i l f
i
Chemical Transformation
y The bonds between the atoms (reactants) will break and new bonds will form elsewhere ( products).
y How to recognize a chemical transformation?
H i h i l f
i
y Emission of gas
Chemical Transformation
y The bonds between the atoms (reactants) will break and new bonds will form elsewhere ( products).
y How to recognize a chemical transformation?
H i h i l f
i
y Emission of gas
y Emission or absorption of heat
Chemical Transformation
y The bonds between the atoms (reactants) will break and new bonds will form elsewhere ( products).
y How to recognize a chemical transformation?
H i h i l f
i
y Emission of gas
y Emission or absorption of heat
y Emission of light
Chemical Transformation
y The bonds between the atoms (reactants) will break and new bonds will form elsewhere ( products).
y How to recognize a chemical transformation?
H i h i l f
i
y Emission of gas
y Emission or absorption of heat
y Emission of light
y Color change
Chemical Transformation
y The bonds between the atoms (reactants) will break and new bonds will form elsewhere ( products).
y How to recognize a chemical transformation?
y Emission of gas
y Emission or absorption of heat
p
y Emission of light
y Color change
y Formation of a precipitation
F
ti f i it ti
Interpretation
CH4 (g) + 2 O2 (g)
y This means:
y
CO2 (g) + 2 H2O (l)
Methane reacts with oxygen to form carbon dioxide and water
Symbol
S
mbol
s
l
g
aq
Physical
Ph
sical State
solid
liquid
gas
aqueous
Conservation of Mass
y Think back…
y Nothing created, nothing lost, all is constant
y The law of conservation of mass: the total mass of the reactants is equal to the total mass of the products
i l h l f h d
Balancing Equations
y When we write chemical equations we must balance, according to the law of conservation of mass
y Therefore take the example of the formation of Th f k h l f h f
i f ammonia
N2(g) + H2(g)
NH3(g)
Count the atoms
Unbalanced vs Balanced
y
N2(g) + H2(g)
NH3(g)
y 2 Nitrogen + 2 Hydrogen 1 Nitrogen 3 Hydrogen
y
N2(g) + H2(g)
2 NH3(g)
y 2 Nitrogen + 2 Hydrogen 2 Nitrogen 6 Hydrogen
y
N2(g) + 3 H
H2(g)
2 NH
NH3(g)
y 2 Nitrogen + 6 Hydrogen 2 Nitrogen 6 Hydrogen
Unbalanced vs Balanced
y
y
y
y
y
y
CH4(g) + O2(g)
CO2(g) + H2O
1 Carbon + 4 Hydrogen + 2 Oxygen 1 Carbon 2 Oxygen + 2 Hydrogen 1 Oxygen
CH4(g)
( ) + O2(g)
( )
CO2(g) ( ) + 2 H2O
1 Carbon + 4 Hydrogen + 2 Oxygen 1 Carbon 2 Oxygen + 4 Hydrogen 2 Oxygen
CH4(g) + 2 O2(g)
CO2(g) + 2 H2O
1 Carbon + 4 Hydrogen + 4 Oxygen 1 Carbon 2 Oxygen + 4 Hydrogen 2 Oxygen
Photosynthesis
CO2 (g) + H2O (l)
C6H12O6 (s) + O2 (g)
What is the balanced equation?
Photosynthesis
CO2 (g) + H2O (l)
C6H12O6 (s) + O2 (g)
What is the balanced equation?
6CO2 (g) + 6H2O (l)
C6H12O6 (s) + 6O2 (g)
Acid‐Base Neutralization
y This is a reaction where an acid and a base react to form the products salt and water
y Acid + Base Salt + Water
A id B S l W
y Acid H+
y Base OH
B OH‐
y HCl + NaOH NaCl + H2O
Acid‐Base
y Examples:
y 1. HF + KOH KF + H2O
y 2. H2SO4 + Mg(OH)2
y 3. HBr + Ca(OH)2
MgSO4 (s) + H2O
CaBr2 (s) + H2O
“Matter and
Change
Change”
Properties of Matter
y OBJECTIVES:
J
y Identify properties of matter as extensive or intensive.
t i i t i
p
Properties of Matter
y OBJECTIVES:
J
y Define physical property, and listt several common physical li
l h i l p p
properties of substances.
p
Properties of Matter
y OBJECTIVES:
J
y Differentiate among three states of matter.
f tt
Properties of Matter
y OBJECTIVES:
J
y Describe a physical change.
Matter
y Matter is anything that: a) has mass, and b) takes up space
)
p p
y Mass = a measure of the amount of “stuff” (or material) the object contains stuff (or material) the object contains (don’t confuse this with weight, a measure of gravity)
f i )
y Volume = a measure of the space p
occupied by the object
Describing Matter
y
Properties used to describe matter can be P
ti d t d
ib tt b classified as:
1)
Extensive – depends on the amount of matter in the sample
‐ Mass, volume, calories are examples
2)
Intensive – depends on the type
p
yp of matter, not the amount present
‐ Hardness, Density, Boiling Point
,
y,
g
Properties are…
y Words that describe matter (adjectives)
W d h d
ib ( dj i )
y Physical Properties‐ a property that can be observed and measured without changing the material’s composition.
y Examples‐ color, hardness, m.p., b.p.
color hardness m p b p
y Chemical Properties‐ a property that can only be observed by changing the composition of the material. y Examples‐
p
ability to burn, decompose, y
,
p ,
ferment, react with, etc.
States of matter
1)
Solid‐ matter that can not flow (definite shape) and has definite volume.
2) Liquid‐
Liquid definite volume but takes the shape of its container (flows).
3) Gas
Gas‐ a substance without definite volume or shape and can flow.
y
Vapor‐ a substance that is currently a gas, but normally is a liquid or solid at room temperature. (Which is correct: “water gas”, or “water vapor”?)
States of Matter
Definite Definite
Volume? Shape?
Solid
Liquid
Gas
YES
YES
NO
Result of a
TemperatureI Will it
Compress?
ncrease?
YES
Small
Expans.
NO
NO
Small
Expans.
NO
NO
Large
Expans.
YES
4th state: Plasma - formed at high
temperatures; ionized phase of
matter as found in the sun
Three Main Phases
Condense
F
Freeze
Evaporate
Melt
S lid
Solid
Li id
Liquid
G
Gas
Copper Phases - Solid
Copper Phases - Liquid
Copper Phases – Vapor (gas)
Physical vs. Chemical Change
y Physical change
will change the visible h
l h
ll h
h
bl
appearance, without changing the composition of the material.
f th t i l
y Boil, melt, cut, bend, split, crack
y Is boiled water still water?
b l d
ll
y Can be reversible, or irreversible
y Chemical change ‐ a change where a new form of matter is formed.
y Rust, burn, decompose, ferment
Mixtures
y OBJECTIVES:
J
y Categorize a sample of matter as a substance or a mixture.
b t
i t
Mixtures
y OBJECTIVES:
y Distinguish between homogeneous and heterogeneous samples of matter.
tu es
Mixtures
y OBJECTIVES:
y Describe two ways that components of mixtures can be separated.
y
Mixtures are a physical blend of at least two substances; have variable composition. b
h i bl i i They can be either:
1)) Heterogeneous –
H t
the mixture is not th i t i t uniform in composition
•
Ch
Chocolate chip cookie, gravel, soil.
l t hi ki l il
2) Homogeneous ‐ same composition th
throughout; called h t ll d “solutions
l ti
”
•
y
Kool‐aid, air, salt water
E
Every part keeps it’s own properties.
k
i ’ i
Solutions are homogeneous mixtures
y Mixed molecule by molecule, thus too small to see the different parts
y Can occur between any state of matter: gas y
g
in gas; liquid in gas; gas in liquid; solid in q ;
(
y ),
liquid; solid in solid (alloys), etc.
y Thus, based on the distribution of their components mixtures are called components, mixtures are called homogeneous or heterogeneous.
Phase?
y The term “phase” is used to describe any part of a sample with uniform composition p
p
p
of properties.
y A homogeneous mixture consists of a single
phase
y A heterogeneous mixture consists of two or more phases.
Separating Mixtures
y Some can be separated easily by physical means: rocks and marbles, iron filings and sulfur (use magnet) g
y Differences in physical properties can be used to separate mixtures.
used to separate mixtures
y Filtration ‐ separates a solid from the li id i h t
liquid in a heterogeneous mixture (by i t (b size) Separation of a Mixture
Separation of a Mixture
Components of dyes such as ink may be
separated by paper chromatography.
Separation of a Mixture
Distillation: takes advantage
of different boiling points.
NaCl boils at 1415 oC
p
Elements and Compounds
y OBJECTIVES:
J
y Explain the differences between an element and a compound.
l
t d d
p
Elements and Compounds
y OBJECTIVES:
J
y Distinguish between a substance and a mixture.
d i t
Elements and Compounds
Elements and Compounds
y OBJECTIVES:
y Identify the chemical symbols of elements, and name
elements
and name elements given their symbols.
Substances are either:
a) elements, or
b) compounds
Substances: element or compound
y Elements‐ simplest kind of matter
y cannot be broken down any simpler and still have properties of that element!
i f h l
!
y all one kind of atom.
y Compounds are substances that can be broken down only by chemical methods
y when broken down, the pieces have completely different p
p
y
properties than the original compound.
y made of two or more atoms, chemically combined (not just a physical blend!)
Compound vs. Mixture
Compound
Mixture
Made of one kind
of material
Made of more than
one kind of material
Made by a
chemical change
Made by a
physical change
Definite
composition
Variable
composition
Which is it?
Mixture
C ompound
Compound
Element
Elements vs. Compounds
Elements vs. Compounds
y Compounds can be broken down into simpler substances by chemical means, b t l
but elements t cannot.
y A “chemical change” is a change that produces matter with a different composition
p
than the original matter.
g
Chemical Change
A change
h
iin which
hi h one or more substances
b t
are converted into different substances.
Heat and
light are
often
evidence
id
off
a chemical
change.
h
Properties of Compounds
Properties of Compounds
y Quite different properties than their component elements
component elements.
y Due to a CHEMICAL CHANGE, the resulting compound has new and different properties:
• Table sugar – carbon, hydrogen, oxygen
• Sodium chloride –
Sodium chloride sodium, chlorine
sodium chlorine
• Water – hydrogen, oxygen
Cl ifi ti
Classification of Matter
f M tt
Symbols & Formulas
y Currently, there are l h
117 elements
l
y Elements have a 1 or two letter symbol, and compounds have a formula.
d h f
l
y An element’s first letter always capitalized; if there is a second letter it is written lowercase: B Ba C Ca H second letter, it is written lowercase: B, Ba, C, Ca, H, He
Chemical Reactions
y OBJECTIVES:
J
y Describe what happens during a chemical change.
h i l h
Chemical Reactions
Chemical Reactions
y OBJECTIVES:
J
y Identify four possible clues that a chemical change has taken h i l h
h t k p
place.
Chemical Reactions
y OBJECTIVES:
J
y Apply the law of conservation of mass to chemical reactions.
t h i l ti
Chemical Changes
Chemical Changes
y The ability of a substance to undergo a specific chemical change is called a chemical property.
• iron plus oxygen forms rust, so the ability to iron plus oxygen forms rust so the ability to rust is a chemical property of iron
y During a chemical change (also called chemical reaction), the composition of matter always changes matter always changes. Chemical Reactions are…
y When one or more substances are changed into new substances.
y Reactants‐ the stuff you start with
y Products
Products‐ what you make
y The products will have NEW PROPERTIES different from the reactants you started with
y Arrow points from the reactants to the new products
d t
Recognizing Chemical Changes
1)
Energy is absorbed or released (temperature changes hotter or colder)
2) Color changes
3) Gas production (bubbling, fizzing, or odor change; smoke)
h
k )
4) formation of a precipitate ‐ a solid that separates from solution (won t dissolve)
from solution (won’t dissolve)
5) Irreversibility ‐ not easily reversed
But there are examples of these that are not chemical But, there are examples of these that are not chemical – boiling water bubbles, etc.
Conservation of Mass y During any chemical reaction, the mass of D i h i l i h f the products is always equal to the mass of the reactants.
h y All the mass can be accounted for:
y Burning of wood results in products that appear to have less mass as ashes; where is the rest?
yLaw of conservation of mass