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Ch 2 Matter & Atoms. Natural Approach to Chemistry Lab Aids Condensed. 2.1 Frames 2-282.2 Frames 29-62 2.3 Fr. 63-106. 2.1 Matter & the Elements. Standards: SC.912.P.8.5 relate properties of atoms & their position in the periodic table to the arrangement of their electrons - PowerPoint PPT Presentation
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Ch 2 Matter & Atoms
Natural Approach to ChemistryLab Aids
Condensed
2.1 Frames 2-28 2.2 Frames 29-62 2.3 Fr. 63-106
2.1 Matter & the Elements
• Standards:• SC.912.P.8.5 relate properties of atoms & their
position in the periodic table to the arrangement of their electrons
• SC.912.P.8.9 apply the mole concept and the law of conservation of mass to calculate quantities of chemicals participating in reactions
The “stuff” that we are made of is called matter.
Chemistry tells us how one kind of matter can be changed into a completely different kind of matter.
What are things made of?
substance: a kind of matter that can’t be separated into other substances by physical means such as heating, cooling, filtering, drying, sorting, or dissolving.
Corn oil is a pure substance
mixture: matter that contains more than one substance.
Corn oil is a pure substance
Oil and vinegar dressing is a mixture of substances
Examples: MassDensityColor
Physical properties can be measured or seen through direct observations.
Physical properties
Physical changes include changes in shape, phase or temperature.
Chemical properties are observed when a substance changes into a different substance.
Iron RustChemical change
Signs that a
chemical change has occurred
Each element is a unique type of atom.
All oxygen atoms are identical.
An oxygen atom is different from a silicon atom or a potassium atom.
element: a substance that cannot be separated into simpler substances by chemical means.
1 grain of rice = 0.01 gram
1 hydrogen atom = 1.678 x 10–24 grams
= 0.000000000000000000000001678 grams
How small is an atom?
The periodic table
The periodic table organizes elements according to how they combine with other elements (based on their chemical properties).
HydrogenLightest elementAtomic number: 1
UraniumHeaviest naturally occurring elementAtomic number: 92
Increasing atomic number
Incr
easin
g at
omic
num
ber
Elements that belong to the same group (column) have similar chemical properties.
Reminder
1 atomic mass unit (amu) = 1.66 x 10-24 g
The atomic mass is the mass of:
1) a single atom in amu.
2) a mole of atoms in grams.
One single hydrogen atom weighs 1.01 amu.
One mole of hydrogen atoms weighs 1.01 g.
What does that mean?
The atomic mass is the mass of:
1) a single atom in amu.
2) a mole of atoms in grams.
One single carbon atom weighs 12.0 amu.
One mole of carbon atoms weighs 12.0 g.
What does that mean?
One mole contains 6.02 x 1023 atoms
Avogadro’s number
How many moles are in 100 g of sulfur (S)?
How many moles are in 100 g of sulfur (S)?
Asked: The number of molesGiven: The element is sulfur and there are 100 gRelationships: One mole of sulfur has a mass of 32.065 g
How many moles are in 100 g of sulfur (S)?
Asked: The number of molesGiven: The element is sulfur and there are 100 gRelationships: One mole of sulfur has a mass of 32.065 g
Solve:
Answer: 100 g of sulfur contains 3.12 moles of sulfur atoms.
110032.065
3.12mole Sg Sg S
moles S
How many grams of calcium (Ca) do you need to have 2.50 moles of calcium?
Asked: The number of gramsGiven: The element is calcium and there are 2.50 molesRelationships: One mole of calcium has a mass of 40.078 g
How many grams of calcium (Ca) do you need to have 2.50 moles of calcium?
Asked: The number of gramsGiven: The element is calcium and there are 2.50 molesRelationships: One mole of calcium has a mass of 40.078 g
Solve:
Answer: 2.50 moles of calcium has a mass of 100. g.
40.0782.501
100.2g Camoles Camole Ca
g Ca
Physical properties can be seen and measured
Chemical properties are observed when one substance is changed into another
Elements are organized in a periodic table This allows to convert
grams to moles and vice versa.
2.2 Molecules and Compounds
Sc.912.P.8.7 interpret formula representations of molecules and compounds in terms of composition and structure.Sc.912.P.8.9 mole concept and law of conservation of mass
One H2 moleculeOne O2 molecule
molecule: a group of atoms chemically bonded together.
molecule: a group of atoms chemically bonded together.
compound: a substance containing more than one element in which atoms of different elements are chemically bonded together.
One H2O moleculeOne H2 moleculeOne O2 molecule
What do all these have in common?
What do all these have in common?
They are made up of only 3 types of atoms: carbon, oxygen and hydrogen.
More than 200,000 words in the English language
Trillions of substances that make up the universe
The alphabet of chemistry
The chemical formula
The chemical formula
Write a chemical formula for a compound that has three hydrogen (H) atoms for each atom of nitrogen (N).
Write a chemical formula for a compound that has three hydrogen (H) atoms for each atom of nitrogen (N).
Asked: Chemical formulaGiven: 3 hydrogen (H) and 1 nitrogen (N)Relationships: The subscript tells the number of each element in the
compound.
Write a chemical formula for a compound that has three hydrogen (H) atoms for each atom of nitrogen (N).
Asked: Chemical formulaGiven: 3 hydrogen (H) and 1 nitrogen (N)Relationships: The subscript tells the number of each element in the
compound.Answer: NH3
The properties of a compound depend more on the exact structure of the molecule
than on the individual elements from which it is made.
F
U
N
E
RA
L
F U N E R A L F U NER A L
The arrangement of letters matters!
The arrangement of atoms matters!
Representation
There are many ways of representing the same thing.
Representation
Ionic compounds
Salt (NaCl) is not a molecule!
ionic compound: a compound such as a salt in which positive and negative ions attract each other to keep matter together.
ion: an atom or small molecule with an overall positive or negative chare as a result of an imbalance of protons and electrons.
Formula mass
The formula mass of water (H2O) is 18 g.
What is the mass of 1 mole of methane (CH4)?
What is the mass of 1 mole of methane (CH4)?
Asked: The mass of 1 mole of methane
Given: Methane (CH4) contains 1 carbon (C) and 4 hydrogen (H) atoms
Relationships: The formula mass is the sum of the atomic masses for each atom in the compound
What is the mass of 1 mole of methane (CH4)?
Asked: The mass of 1 mole of methane
Given: Methane (CH4) contains 1 carbon (C) and 4 hydrogen (H) atoms
Relationships: The formula mass is the sum of the atomic masses for each atom in the compound
Solve:
Answer: One mole of methane (CH4) has a mass of 16.04 g. 44 4 1.0079 12.0 16.0411 g CH
moH
eC
l
How many moles are in 100 grams of water (H2O)?
How many moles are in 100 grams of water (H2O)?
Asked: The moles in 100 g of water
Given: Water (H2O) contains 2 hydrogen (H) atoms and 1 oxygen (O)
atom.
Relationships: The formula mass is the sum of the atomic masses for each atom in the compound.
How many moles are in 100 grams of water (H2O)?
Asked: The moles in 100 g of water
Given: Water (H2O) contains 2 hydrogen (H) atoms and 1 oxygen (O)
atom.
Relationships: The formula mass is the sum of the atomic masses for each atom in the compound.
Solve:
Answer: 100 g of water (H2O) contains 5.55 moles.
2
5
2 2 1.0079 15.999 18.015
110018.01
55
. 5
gH O H Omole
molegg
moles
How many grams are in 2.300 moles of butane (C4H10)? Butane is used as a lighter fluid in disposal lighter.
How many grams are in 2.300 moles of butane (C4H10)? Butane is used as a lighter fluid in disposal lighter.
Asked: The mass in grams of 2.300 moles of butane
Given: 2.300 moles of C4H10
Relationships: The formula mass is the sum of the atomic masses for each atom in the compound.
How many grams are in 2.300 moles of butane (C4H10)? Butane is used as a lighter fluid in disposal lighter.
Asked: The mass in grams of 2.300 moles of butane
Given: 2.300 moles of C4H10
Relationships: The formula mass is the sum of the atomic masses for each atom in the compound.
Solve:
Answer: 133.7 g are in 2.300 moles of butane (C4H10).
4 1
2
4 10
00
4 1
4 10 4 12.011 10 1.0079 58.12
133.7
3
58.1232.300
1
gH O H Omole
g C Hgmo
gle mole C
C HH
How many oxygen atoms are in 200.0 g of glucose (C6H12O6)?
Asked: Number of oxygen atoms
Given: 200.0 g of C6H12O6
Relationships: Formula mass of glucose:
6 12 6
6 12.011 12 1.0079 6 15.9 19 80.159
C Og
m e
H
ol
Remember: Avogadro’s number indicates that one mole contains 6.02 x 1023 atoms
Solve: First we find how many moles are in 200.0 g of glucose:
6 12 66 12 6
6 16 12 6
2 6
1200.0
180.1.11
150
mole C molesH O Cg C H Og H
H OC O
Solve: First we find how many moles are in 200.0 g of glucose:
Next we find how many molecules are contained in 1.11 moles of glucose:
6 12 66 12 6 6 12 6
6 12 6
1200.0 1.110
180.15mole C H Og C H O moles C H O
g C H O
236 12
2
66 12 6
6 12 6
36 12 6
6.022 101.110
1
6.684 10
molecules C H Omoles C H
molecules
O
C
mole C
O
H O
H
Solve: First we find how many moles are in 200.0 g of glucose:
Next we find how many molecules are contained in 1.11 moles of glucose:
Then we find how many O atoms are contained in 6.684 x 1023 molecules of glucose:
6 12 66 12 6 6 12 6
6 12 6
1200.0 1.110
180.15mole C H Og C H O moles C H O
g C H O
236 12 6
6 12 66 12 6
236 12 6
6.022 101.110
1
6.684 10
molecules C H Omoles C H Omole C H O
molecules C H O
236 12 6
6 1 6
24
2
4.66.684 101
010 10O atomsmolecules C H Omolecule C H O
O atoms
Solve: First we find how many moles are in 200.0 g of glucose:
Next we find how many molecules are contained in 1.11 moles of glucose:
Then we find how many O atoms are contained in 6.684 x 1023 molecules of glucose:
Answer: There are 4.010 x 1024 atoms of O in 200.0 g of glucose (C6H12O6).
6 12 66 12 6 6 12 6
6 12 6
1200.0 1.110
180.15mole C H Og C H O moles C H O
g C H O
236 12 6
6 12 66 12 6
236 12 6
6.022 101.110
1
6.684 10
molecules C H Omoles C H Omole C H O
molecules C H O
236 12 6
6 1 6
24
2
4.66.684 101
010 10O atomsmolecules C H Omolecule C H O
O atoms
We can build compounds using atoms- The type of atom matters
- The arrangement of atoms also matters
We can calculate the formula mass of compounds:
2.3 Mixtures and Solutions
Sc.912.P.8.9 mole concept and law of conservation of massSc.912.P.12.12 explain how various factors such as concentration, temperature, and presence of a catalyst affect the rate of a chemical reaction
CHAPTER 2
Matter and Atoms
2.3 Mixtures and Solutions
A recipe calls for you to “mix until homogeneous.”
What does that mean?
A mixture that is uniform throughout.
A mixture that is uniform throughout. Different samples may have different compositions.
What happens when sugar is added to water?
What happens when sugar is added to water?
A solution is obtained.
Is orange juice a solution?
Hint: Are things dissolved in orange juice?
Is orange juice a solution?
It is partially a solution because some chemicals are dissolved in water, but some bits (like pulp) are not.
These four solutions contain the same solvent and solute.
Which one is the most concentrated solution?Which one is the most dilute solution?
concentration: the amount of each solute compared to the total solution.
• Can you dissolve salt in water?
VariablesAmount of saltAmount of water
• Can you dissolve salt in water?
• Can you continue adding more and more salt, and still get a solution?
Variables
Amount of saltAmount of water
• Can you dissolve salt in water?
• Can you continue adding more and more salt, and still get a solution?
• Can you dissolve more salt when you increase the temperature?
Variables
Amount of saltAmount of water
Amount of saltAmount of waterTemperature
solubility: the amount of a solute that will dissolve in a particular solvent at a particular temperature and pressure.
Solubility of common substances in water at 25oC
If the concentration of a sugar solution is 75 g/L, how much solution do you need if you want 10 g of sugar?
If the concentration of a sugar solution is 75 g/L, how much solution do you need if you want 10 g of sugar?
Asked: Volume of solution
Given: 10 g of solute and concentration of 75 g/L
Relationships:mass of soluteLiters of solution
concentration in g L
If the concentration of a sugar solution is 75 g/L, how much solution do you need if you want 10 g of sugar?
Asked: Volume of solution
Given: 10 g of solute and concentration of 75 g/L
Relationships:
Solve:
mass of soluteLiters of solutionconcentration in g L
10 0.1 1333375
g L org
LL
m
How much menthol do you need to make 10 kg of mouthwash if the concentration of menthol must be 0.05%?
How much menthol do you need to make 10 kg of mouthwash if the concentration of menthol must be 0.05%?
Asked: Mass of solute
Given: 10 kg of solution, solute concentration of 0.05%
Relationships: %100
concentration inmass of solute mass of solution
How much menthol do you need to make 10 kg of mouthwash if the concentration of menthol must be 0.05%?
Asked: Mass of solute
Given: 10 kg of solution, solute concentration of 0.05%
Relationships:
Solve:
%100
concentration inmass of solute mass of solution
0.05%10 0.00510
50
kg kg or g
molarity: the number of moles of solute per liter of solution.
( )( )
amount of solute moles molesmolarityvolume of solvent liters L
moles ML
If 10.0 g of citric acid (C6H8O7) is added to 500 mL of water, what is the molarity of the resulting solution?
Asked: The molarity of a solution
Given: The amount of solute (citric acid) and the volume of solution
Relationships:
moles solutemolarityvolume of solution L
If 10.0 g of citric acid (C6H8O7) is added to 500 mL of water, what is the molarity of the resulting solution?
Asked: The molarity of a solution
Given: The amount of solute (citric acid) and the volume of solution
Relationships:
Solve: Start by calculating the formula mass of C6H8O7:
moles solutemolarity
volume of solution L
6 12.011 8 1.0079 7 1 192.5. 12999 g mole
If 10.0 g of citric acid (C6H8O7) is added to 500 mL of water, what is the molarity of the resulting solution?
Asked: The molarity of a solution
Given: The amount of solute (citric acid) and the volume of solution
Relationships:
Solve: Start by calculating the formula mass of C6H8O7:
Next we calculate the number of moles in 10.0 g of C6H8O7:
moles solutemolarity
volume of solution L
6 12.011 8 1.0079 7 15.999 192.12 g mole
1# 10.0192.12
0.0521molemoles gg
moles
If 10.0 g of citric acid (C6H8O7) is added to 500 mL of water, what is the molarity of the resulting solution?
If 10.0 g of citric acid (C6H8O7) is added to 500 mL of water, what is the molarity of the resulting solution?
Asked: The molarity of a solution
Given: The amount of solute (citric acid) and the volume of solution
Relationships:
Solve: Start by calculating the formula mass of C6H8O7:
Next we calculate the number of moles in 10.0 g of C6H8O7:
Answer:
moles solutemolarity
volume of solution L
6 12.011 8 1.0079 7 15.999 192.12 g mole
1# 10.0 0.0521192.12molemoles g moles
g
0.05210.500
0.104molesmolarityL
M
Ascorbic acid = Vitamin C
Vitamin C acts as a food preservative by reacting with oxygen (O2)Ascorbic acid
C6H8O6
How much (volume) of a 1 M ascorbic acid solution will completely react with 0.02 moles of oxygen (O2)?
Asked: Volume of solution
Given: Concentration (1M) and balanced reaction
Relationships:
According to the balanced reaction we need 2 moles of ascorbic acid for every mole of O2.
moles solutemolarity
volume of solution L
How much (volume) of a 1 M ascorbic acid solution will completely react with 0.02 moles of oxygen (O2)?
Asked: Volume of solution
Given: Concentration (1M) and balanced reaction
Relationships:
According to the balanced reaction we need 2 moles of ascorbic acid for every mole of O2.
Solve: That means we need 0.04 moles of ascorbic acid:
0.04 0 41
0.04moles solute molesvolume L L ormolarit
LM
my
moles solutemolarity
volume of solution L
How much (volume) of a 1 M ascorbic acid solution will completely react with 0.02 moles of oxygen (O2)?
Asked: Volume of solution
Given: Concentration (1M) and balanced reaction
Relationships:
According to the balanced reaction we need 2 moles of ascorbic acid for every mole of O2.
Solve: That means we need 0.04 moles of ascorbic acid:
Answer: 40 mL of the solution contains 0.04 moles of ascorbic acid, which is enough to react with 0.02 moles of oxygen (O2).
0.04 0 41
0.04moles solute molesvolume L L ormolarit
LM
my
moles solutemolarity
volume of solution L
How much (volume) of a 1 M ascorbic acid solution will completely react with 0.02 moles of oxygen (O2)?
The air you breathe is a mixture!
Air takes up less space under high pressure.
Standard
Temperature and
Pressure
molar volume: the amount of space occupied by a mole of gas at STP. It is equal to 22.4 L.
0oC
1 atm
Partial pressures
The total pressure in a mixture of gases is the sum of
the partial pressures of each individual gas
in the mixture.
Gas A
Gas BGas C
Gas A Gas B
Gas CTotal pressure
=
+
+
Partial pressure of A
Partial pressure of C
Partial pressure of B
Partial pressures
If 1 L of helium (75%) and neon (25%) is at STP, what is the partial pressure of helium?
Asked: Partial pressure of helium
Given: 75% He and 25% Ne at STP conditionsStandard pressure is 101,325 Pa or 1 atm
Relationships: The total pressure is the sum of the partial pressures of each gas.
If 1 L of helium (75%) and neon (25%) is at STP, what is the partial pressure of helium?
Asked: Partial pressure of helium
Given: 75% He and 25% Ne at STP conditionsStandard pressure is 101,325 Pa or 1 atm
Relationships: The total pressure is the sum of the partial pressures of each gas.
Solve: 75,9940.75 101,30.75
250.75 1
Paor
Paatmatm
or
If 1 L of helium (75%) and neon (25%) is at STP, what is the partial pressure of helium?
Asked: Partial pressure of helium
Given: 75% He and 25% Ne at STP conditionsStandard pressure is 101,325 Pa or 1 atm
Relationships: The total pressure is the sum of the partial pressures of each gas.
Solve:
Answer: The partial pressure of helium is 75,994 Pa or 0.75 atm.
75,9940.75 101,30.75
250.75 1
Paor
Paatmatm
or
If 1 L of helium (75%) and neon (25%) is at STP, what is the partial pressure of helium?
STP conditions:
Standard
Temperature (0oC)
Pressure (1 atm)
Air is a mixture of gases. Based on Dalton’s law of partial pressures:
2 2...air N O ArP P P P
Concentration of a solution can be expressed in:mass per volumemass percentmolarity
moles of solutemolarity Mliters of solvent