Post on 26-Dec-2015
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Review Unit 3
Final Jeopardy
300
500
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100
Counting ParticlesCounting Particles
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500
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Chemical Rxns
Chemical Rxns StoichiometryStoichiometryMole StuffMole Stuff
Avogadro & His Number
PLUS MORE!
Avogadro & His Number
PLUS MORE!
600
100
600 600 600 600
Mole Stuff 100 - Answer
A volumetric unit of measure.
One mole has as many particles in it as Avogadro’s number.
Mole Stuff200 - Answer
The molar mass is the mass of one mole of substance.
It can be found by reading the atomic masses on the periodic table.
Mole Stuff300 - Answer
Relative masses are masses relative to the smallest mass
available.
The atomic masses on the Periodic Table are all relative to Hydrogen.
Mole Stuff500 - Answer
0.075 moles Fe2O3
Molar mass Fe2O3: 159.6 g/mol
(12g) * (1mol/159.6g) = 0.075 mol
Mole Stuff600 - Answer
1.11 grams Ca(OH)2
Molar Mass Ca(OH)2: 74 g/mol
(0.015mol) * (74g/1mol) = 1.11 g
Avogadro & His Number100 - Answer
6.02 x 1023
This is how many particles are in one mole of substance
Avogadro & His Number200 - Answer
3.63 x 1021 atoms
(0.65g) * (1mol/107.9g) * (6.02x1023part/1mol) =
3.63 * 1021 particles
Counting Particles 300
A 9.56 g sample of copper (II) sulfide is found to contain
6.35 g of copper. What is the percent by mass of the copper and sulfur in this compound?
Counting Particles 300 - Answer
66.4% Cu and 33.6% S
(6.35gCu/9.65g)*100% = 66.4%
(3.21gS/9.65g)*100% = 33.6%
Counting Particles 400
Given the diagram of the molecule below, write the empirical and molecular formulas. Label each.
= H
= C
Counting Particles 500
When 0.062 g of phosphorus burns in air, it forms 0.142 g of phosphorus oxide. Determine the empirical formula of phosphorus oxide.
Counting Particles 500 - Answer
P2O5
Convert mass to moles Ratio of Moles Whole #(0.062g P)*(1mol P/31g P) = 0.002mol P 1 x2 = 2
(0.08g O)*(1mol O/16g O) = 0.005mol O 2.5 x2 = 5
Counting Particles 600
What is the molecular formula of each compound?
Empirical Formula Actual Molar Mass of Compound
CH 78 g/mole
NO2 92 g/mole
Chemical Rxns 300
A reaction takes place in a test tube. You feel the bottom of the tube and it feels warm. Is the reaction exothermic or endothermic? WHY?
Chemical Rxns 300 - Answer
EXOTHERMIC
The system is releasing heat to the surroundings – energy is exiting the system and moving into your hand.
Chemical Rxns 400
Write a balanced chemical reaction for the reaction below:
Magnesium hydroxide reacts with nitric acid (HNO3) to form water and magnesium nitrate.
Chemical Rxns 600Write a balanced chemical reaction for the
following reaction:
The combustion of ethane gas, C2H6, produces carbon
dioxide gas and water vapor. This reaction is exothermic.
Stoichiometry100 - Answer
The coefficients tell us how many of each molecular are involved in the reaction.
They also tell us the ratio (in moles) of each compound to the others.
Stoichiometry 200
Hydrogen sulfide (H2S) burns in air to produce sulfur dioxide and water. How many moles of oxygen gas would be needed to completely burn 8 moles of hydrogen sulfide?
Stoichiometry 200 - Answer
12 mol O2
Equation: 2H2S + 3O2 2SO2 + 2H2O
Before: 8 mol xs 0 mol 0 mol
Change: -8 mol x(3/2) 12 mol +8 mol +8 mol
After: 0 mol xs 8 mol 8 mol
Stoichiometry300
What is the ratio of moles of oxygen gas to moles of carbon dioxide in the reaction below?
2C2H6 + 7O2 4CO2 + 6H2O
Stoichiometry 400 - Answer
No grams allowed! Only moles.
The ratios in a chemical reaction only apply for moles of each substance.
Stoichiometry500Calculate the number of moles of sodium oxide
that should be produced when 6.50 grams of sodium react with oxygen gas.
Stoichiometry 500 - Answer
0.14 mol Na2O
(6.5g Na)*(1mol/23g Na) = 0.28 mol Na
Equation: 4Na + O2 2Na2O
Before: 0.28mol xs 0 mol
Change: -.28mol -.07mol +0.14mol
After: 0 mol xs 0.14 mol
Stoichiometry 600 - Answer………
Use ratios to determine the amounts of substances that are used up, formed, or produced within a chemical reation.