kf chemistry 1 st 6 weeks exam review week 6 cca september 26, 2014
TRANSCRIPT
KF Chemistry1st 6 weeks Exam Review
Week 6 CCASeptember 26, 2014
Pure Substances vs. Mixtures
• Pure substance: matter that has a fixed (constant) composition and unique properties. Contains only 1 type element or compound; homogeneous
MixtureMixture: : Contains at least 2 Contains at least 2 PHYSICALLYPHYSICALLY
combined compounds; can be homogeneouscombined compounds; can be homogeneous
or heterogeneousor heterogeneous
Elements• pure substance that cannot be separated into
simpler substance by physical or chemical means.
Compounds
Pure substance composed of two or more different elements joined by chemical bonds.
– Made of elements in a specific ratio that is always the same– Has a chemical formula– Can only be separated by chemical means, not physically
Mixtures• A combination of two or more pure
substances that are not chemically combined. Zn + Cu
• substances held together by physical forces, not chemical
• No chemical change takes place • Each item retains its properties
in the mixture • They can be separated physically
3 classes of MIXTURES
Solution homogenous
Colloid homogenous
Suspension heterogenous
Examples salt water, air
Soot, fog, mayonnaise
Muddy water, Italian dressing
Particle Type ions, atoms Small Clusters Large Clusters
Particle Size
Scatter Light? (TYNDALL EFFECT)
Settle while standing?
Separate by filtration?
small medium large
No
No
No
No
No
yes yes
yes
yes
Mixtures vs. Compounds
http://www.bbc.co.uk/schools/ks3bitesize/science/chemistry/elements_com_mix_6.shtml
Properties of Matter (4D, Level 3)
• Identify each of the following items as a mixture or a pure substance.• - If a mixture, identify as homogeneous or heterogeneous.• - If a pure substance, identify as a compound or an element.
Sample Type of Sample Type of Mixture or Pure
Substance
Gold
Water
Italian Dressing
Milk
Cobalt
Coffee
Calcium Carbonate
Cake Batter
Physical Properties• Physical Property: Can be observed without
changing the substance composition– Ex: Hardness, Color, Conductivity, Malleability, Melting
Point, Boiling Point
• Physical Change: Properties of the material may change, but the COMPOSITION does not
Gallium – MP is 30°C
Water – MP is 0°C
Chemical Properties• Chemical Property: Can ONLY be observed by
changing the substance composition– Ex: Burn, rot, rust, decompose, ferment, explode,
corrode
• Chemical Change: The COMPOSITION of matter ALWAYS changes
• Also called a chemical reaction
Properties of Matter (4A, Level 2)
• Identify the following properties as physical or chemical.Property Physical Property Chemical Property
Temperature
Bond Strength
Calorie Content
Mass
Density
Reactivity
Length
Melting Point
Properties of Matter (4A, level 3)
• Identify the following changes as physical or chemical.Property Physical Change Chemical Change
A rock is crushed
Condensation of water vapor
Pancakes cook
Salt is dissolved in water
An apple is cut
Food is digested
Alcohol evaporates
Ice melts
Extensive vs. Intensive Properties
• Extensive Properties: Depends on amount• Ex: Volume
• Intensive Properties: Depends on type of matter• Ex: Hardness
Properties of Matter (4B, Level 3)
• Identify the following properties as extensive or intensive.
Property Extensive Property Intensive Property
Temperature
Bond Strength
Calorie Content
Mass
Density
Reactivity
Length
Melting Point
States of Matter• Solid:
• Definite Shape • Definite Volume• Incompressible
• Liquid: • Indefinite Shape• Definite Volume• Not Easily Compressed
• Gas: • Indefinite Shape• Indefinite Volume• Easily compressed
Solid Liquid Gases
Density
Viscosity
Compressibility
Structure
Shape
Volume
Movement
Draw a Picture-Nanoscopic Eyes
States of Matter
The Law of Conservation of Mass
Law of Conservation of MassDuring a chemical change, matter is neither created nor destroyed.
According to the law of conservation of mass, how much zinc was present in the zinc carbonate?
A 40 gB 88 gC 104 gD 256 g
(All practice problems are from TEA released TAKS Tests)
In the procedure shown above, a calcium chloride solution is mixed with a sodium sulfate solution to create the products shown. Which of the following is illustrated by this activity?(A) The law of conservation of mass(B) The theory of thermal equilibrium(C) The law of conservation of momentum(D) The theory of covalent bonding
Use SIGNIFICANT FIGURES to answer• All non-zero numbers are significant
EX: 23.4 is 3 sig.figs., 19 is 2 sig.figs., etc.• All zeros between numbers are significant—
EX: 2003 is 4s.f., 2.07 is 3 s.f., 1.009 is 4 s.f. (captive zeros)• All zeros to the right of numbers aren’t significant if there’s no decimal
EX: 1200 is 2s.f., 1000 is 1. (trailing zeros)• All zeros to the left of numbers aren’t significant if there’s no number in front
EX: 0.0045 is 2s.f. (Leading zeros)• All zeros after a number and a decimal are significant EX: 1.00 is 3 s.f. 230.0 is 4 s.f.
When multiplying and dividing, use the least number of significant figures in your answer.When adding and subtracting, use the least number of decimal places in your answer.
LOOK AT YOUR FORMULA SHEET FOR THE RULES! ! !
SIG FIGS-NOW YOU TRY IT
1. 22.4 x 1.2= 5. 561.25 + 105.2=
2. 1036 x 2.00= 6. 124.12 - 104.121=
3. 0.00686/19.00= 7. 343.2 x 510=
4. 1.200/13.686= 8. 100.25 + 68.750=
Scientific NotationOpen (Enter 6.022nd (Blue or Yellow button)EE ( , button above 7)Type in the exponent 23)
Your screen looks like: (6.02E23)
Close )
Open (
EE
2nd
6
.03
DO NOT ENTER x 10
22
(6.02E23)
change these numbers from Standard Notation to Scientific Notation
1) 9872432
2) .0000345
3) .08376
4) 5673
5) 356890
6) 80345
7) 0.00000075
8) 1000
Use this example to help you learn how to find neutrons
Example: Carbon (C)Atomic Number = 6Mass Number = 12
#Protons = 6#Electrons = 6#Neutrons = (mass number) – (atomic number)
= (12) – (6) = 6
Element Name
Symbol Atomic Number
MassNumber
Number of Electrons
Number of Protons
Number of Neutrons
aluminum Al 13 13 13 14
bismuth
calcium 20
copper
iodine 129
82
8
50
30
Isotopes of Carbon Naturally occurring carbon consists of three isotopes, 12C, 13C, and 14C. State the
number of protons, neutrons, and electrons in each of these carbon atoms.
12C 13C 14C 6 6 6
#P _______ _______ _______
#N _______ _______ _______
#E _______ _______ _______
Average Atomic Mass35Cl has atomic mass 34.97 amu (75.76%) and 37C has atomic mass 36.97 amu
(24.24%). • Use atomic mass and relative abundance of each isotope to calculate the
contribution of each isotope to the weighted average.
34.97 x 75.76 = 26.49 amu 10036.97 x 24.24 = + 8.961 amu
100 • Sum is atomic mass of Cl 35.45 amu
Use this worked to example to practice the upcoming problems!
28
Average Atomic Mass of Magnesium
Isotopes Mass of Isotope Abundance 24Mg = 24.0 amu 78.70% = ______
25Mg = 25.0 amu 10.13% = ______
26Mg = 26.0 amu 11.17% = ______
Find the Average Atomic mass of Magnesium
29
Average Atomic Mass of Boron
Isotopes Mass of Isotope Abundance
10B = 10.013 amu 19.8% = ______
11B = 11.009 amu 80.02% = ______
Find the Average Atomic mass of Boron
Contrast & Compare Fission vs. Fusion
ALPHA & BETA DECAY (12B, Level 3)What is the alpha particle?__________________________________________
What is the beta particle?___________________________________________
Define gamma rays________________________________________________