Chemical Changes vs Physical Changes Physical changes are changes in the physical appearance state or size of a substance Chemical changes are changes in the arrangements and connections between ions and atoms and a change in chemical properties ID: 599143
Download Presentation The PPT/PDF document "CHEMICAL Equations" is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.
Slide1
CHEMICAL EquationsSlide2
Chemical Changes vs. Physical Changes
Physical changes are
changes in the physical appearance, state or size of a substance
.Chemical changes are changes in the arrangements and connections between ions and atoms, and a change in chemical properties.Slide3
Example of a physical change:
Melting IceSlide4
Example of a chemical change:
“Burning” Magnesium RibbonSlide5
Is a representation (in
words
or
symbols) of a chemical reactionProvides information about:The reactants (
the starting materials)The products (
the materials produced
)
Chemical EquationsSlide6Slide7
Not much information other than the elements/compounds involved
Potassium metal + oxygen gas
potassium oxide
WORD EQUATION
Reactants are on the left-hand side of the equation
Products are on the right-hand side of the equation
Arrow means produces/yields/ makes
+ sign means “reacts with”Slide8
Components of a Chemical Equation
Coefficients-
numbers in front of the formulae that show the ratio of the reactant(s) and product(s)
States of matter- indicate the state of the substance reacting or being produced ; (g)= gas,
(l)= liquid, (aq)= aqueous, and (s) = solid
6 CO
2(g)
+ 6 H
2
O
(g)
C
6
H12O
6(s) + 6 O2
(g) Slide9
States of matter:
A small piece of sodium which lived in a test tube fell in love with the Bunsen burner: "Oh Bunsen, my flame. I melt whenever I see you . . .", the sodium pined. "It's just a phase you're going through", replied the Bunsen burner. Slide10
In order to determine how many atoms of each element are involved in a chemical equation you must always watch two things:
The subscripts in the formula
The coefficient in front of the formula
Counting Atoms in Equations
CuCl
2
2
H
2
O
Means 2 chlorine atoms/ ions in the molecule
Means two water molecules, each of which has 2 H atoms and 1 oxygen atomSlide11
How many oxygen atoms are indicated by each formula:
Examples of counting atoms
CO
C
6H12
O
6
2 SO
2
Mg(OH)
2
3Sn(Cr
2
O
7
)
21642
42Slide12
ASIDE! THE “FANCY SEVEN”
When these atoms are elements (i.e. they are all on their own) they are
DIATOMIC
(they are in pairs)
e.g. N
2
O
2
F
2
Cl
2
Br
2
I
2 H2 Slide13
Law of Conservation of Mass
This LAW states that the total mass of all products always equals the total mass of all reactants