Upload
susan-perry
View
232
Download
0
Tags:
Embed Size (px)
Citation preview
CHEMISTRY WARM UP (BACK TO CONVERSIONS!!!!)
Convert the following: 5.5 dozen apples = _____ kg apples (1 dozen
= 2.0 kg apples)
3 dozen apples = _____ bushel apples (1 dozen apples = .20 bushel apples)
SECTION 1 THE MOLE: A MEASUREMENT OF MATTER
What are three methods for measuring the amount of something?
How is avogadro’s number related to a mole of any substance?
How is the atomic mass of an element related to the molar mass of an element?
How is the mass of a mole of a compound calculated?
Mole Avogadro’s Number Representative
Particle Molar Mass
Key Concepts Vocabulary
HOW DO WE MEASURE THINGS WE CAN’T SEE LIKE THE ATOM?
The Mole – the animal The Mole – chemistry
MEASURING MATTER
Measure the amount of something by: Count (how many) Mass (g) Volume (mL or cm3)
MATTER
Composed of: Atoms Molecules Ions
Counting them would take forever!
THE MOLE-A UNIT THAT IS A SPECIFIC NUMBER OF PARTICLES
One Mole 6.02 x 1023 “representative particles” Avogadro’s Number
“Representative Particles” Atoms
1 mole of Aluminum = 6.02 x 1023 atoms Molecules
1 mole of H20 = 6.02 x 1023 molecules
Formula Units (a.k.a. ionic compounds) 1 mole of CaF2 = 6.02 x 1023 formula units
AMEDEO AVOGADRO DI QUAREGNA
Italian scientist Helped clarify the
difference between atoms and molecules
CONVERTING NUMBER OF REP. PARTICLES TO MOLES
Generic conversion:1 mole = 6.02 x 1023 “representative particles”
Examples: How many atoms in one mole of Copper?
How many formula units in 2 moles of NaCl?
PRACTICE
How many atoms are on three moles of Calcium?
How many molecules are in 2.5 moles of Al2Cl6?
How many formula units are in 10 moles of NaCl?
PRACTICE WORKSHEET
WARM UP
How many moles is 2.80 x 1024 atoms of Silicon?
How many formula units in 2 moles of MgBr2?
CONVERTING MOLES TO NUMBER OF ATOMS (IN A COMPOUND)
First, figure out the number of atoms in the compound.
Example: H20 3 atoms per molecule
1 mole of H20 contains 6.02x1023 molecules BUT each molecule of water contains 3 atoms
Moles Molecules Atoms
CLASS EXAMPLE:
Propane is a gas used for cooking and heating. How many atoms are in 2.12 mol of propane? (C3H8)
PRACTICE:
How many atoms are in 1.14 mol of SO3?
How many moles are in 4.65x1024 atoms NO2?
THE MASS OF A MOLE OF AN ELEMENT
MOLAR MASS
Numbers under the elements on the periodic table
The mass of ONE mole of a substance Example:
Molar mass of Carbon = 12.0 grams 1 mole of Carbon = 12.0 grams
Molar Mass of Oxygen = 16.0 grams 1 mole of Oxygen = 16.0 grams
EXAMPLE
How many moles is 2 grams of Lithium?
How many grams is 5 moles of Tin?
ONE MOLE OF VARIOUS ELEMENTS
MOLAR MASS CONTINUED…JUST THINK!
1 mole of hydrogen has 6.02x1023 atoms and weighs 1.008 grams…
1 mole of carbon has 6.02x1023 atoms and weighs 12 grams…
How can they have the same number of atoms but weigh different amounts?
THE MASS OF A MOLE OF A COMPOUND
MOLAR MASS OF A COMPOUND
To calculate the molar mass of a compound: Separate out EACH element Count the number of that element Multiply by the molar mass Add the masses of the elements in the
compound
Example: SO3Element Number
ofMolar Mass
Total Mass
S
O
EXAMPLE
H2O
CH4
C6H12O6
SECTION 1 ASSESSMENT - JIGSAW 1. What are three ways to measure the amount
of something? 2. Describe the relationship between Avogadro’s
number and one mole of any substance. 3. How is the atomic mass of an element related
to the molar mass of the element? 4. How can you calculate the mass of a mole of
a compound? 5. How many moles is 1.50 x 1023 molecules of
NH3? 6. How many atoms are in 1.75 mol CHCl3?
7. What is the molar mass of CaSO4? 8. How many moles are in 4.65 x 1024 molecules
of NO2?
SECTION 2
Convert the mass of a substance to the number of moles
What is the volume of a gas at STP
Avogadro’s hypothesis
Standard Temperature and Pressure (STP)
Molar Volume
Key Concepts Vocabulary
THE MOLE-MASS RELATIONSHIP
Use the molar mass of an element or compound to convert between the mass of a substance and the mass of a substance.
Conversion factor: molar mass = 1 mole
Equations: Mass(grams) = number of moles x
mass(grams) 1
mole
Moles = number of grams x ___1 mole____ mass(grams)
Molar Mass
CLASS EXAMPLES:
Aluminum satellite dishes are resistant to corrosion because the aluminum reacts with oxygen in the air to form a coating of aluminum oxide (Al2O3). This tough, resistant coating prevents any further corrosion. What is the mass of 9.45 mol of aluminum oxide?
CLASS EXAMPLE
When iron is exposed to air, it corrodes to form red-brown rust. Rust is iron(iii)oxide (Fe2O3). How many moles of iron oxide are contained in 92.2 g of pure iron oxide?
PRACTICE
Find the mass in grams of 4.52 x 10-3 mole C20H42.
Calculate the mass, in grams, of 2.50 mole of iron(ii)hydroxide.
PRACTICE
Find the number of moles in 3.70 x 10-1 g of boron.
Calculate the number of moles in 75.0 g of dinitrogen trioxide.
PRACTICE WORKSHEET
PRACTICE: FIND THE MASS, IN GRAMS, OF 1.00 X 1023 MOLECULES OF N2.
PRACTICE: FIND THE MASS IN GRAMS OF 2.00 X 1023 MOLECULES OF F2
PRACTICE: HOW MANY ATOMS OF NITROGEN ARE IN 1.2 GRAMS OF ASPARTAME? C14H18N2O5
PRACTICE: FIND THE MASS IN 2.6 X 1043 MOLECULES OF LITHIUM BROMIDE.
THE MOLE-VOLUME RELATIONSHIP
AVOGADRO’S HYPOTHESIS
The equal volumes of gases at the same temperature and pressure contain equal numbers of particles Despite differences in the size of the atoms Due to the fact that the gas particles are so far
apart
S.T.P.
Gases are measured at Standard Temperature and Pressure B/C of variations that result in volume
STP Temperature: 0 degrees Celcius (273 K) Pressure: 101.3 kPa or 1 atm
MOLAR VOLUME
At STP: 1 mol or 6.02 x 1023 representative particles
of any gas occupies a volume of 22.4 L.
CALCULATING VOLUME AT STP
Convert MOLES of gas to the VOLUME of gas at STP
Conversion factor: 22.4 L = 1 mol
CLASS EXAMPLE:
Sulfur dioxide is a gas produced by burning coal. It is an air pollutant and one of the causes of acid rain. Determine the volume, in liters, of 0.60 mol sulfur dioxide at STP.
EXAMPLES
What is the volume of these gases at STP? 3.20 x 10-3 mol CO2
3.70 mol N2
EXAMPLES
At STP, how many moles does each of the following gases occupy?
1.25 L He
0.335 L C2H6
PRACTICE
What is the volume, in Liters, of 15 g of H2 at STP?
What is the volume, in Liters, of 3.4 x 1028 molecules of O2 at STP?
PRACTICE WORKSHEET
CALCULATING MOLAR MASS FROM DENSITY
Density: Measured in grams per liter (g/L)
General Equation Molar Mass = density at STP x molar volume
at STP
Grams = grams x 22.4L Mole L Mole
CLASS EXAMPLE
The density of a gaseous compound containing carbon and oxygen is found to be 1.964 g/L at STP. What is the molar mass of the compound?
EXAMPLES
A gaseous compound composed of sulfur and oxygen, which is linked to the formation of acid rain, has a density of 3.58 g/L at STP. What is the molar mass of this gas?
EXAMPLES
What is the density of krypton at STP?
SECTION ASSESSMENT (10.2)