# Unit 8 packet - ChemistryFall2011

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UNIT 8 PACKET
Notes: The Mole (1 Step Problems)
Date:
Converting…
Moles atoms or molecules or
particles
Conversion Factor
Moles  volume
Moles atoms or molecules
Examples:
1 dozen egg = 12 eggs. How many eggs are in 3 dozen eggs?
1 atm of pressure = 760 torr. How many torr are in 2 atm of pressure?
1 mole of anything = 6.02 x 1023 particles/atoms/molecules. How many particles are in 2 moles of oxygen?
How many particles are in 4.8 moles of hydrogen?
***Scientific notation review:
-To multiply numbers in scientific
notation:
How many particles are in 134 moles of sugar?
If you have 8.9 x 1035 particles of water, how many moles do you
have?
-To divide numbers in scientific notation:
Molar Mass- the mass of ________ ________________ of a given
element or compound
- (use the ________ ________________ on the periodic table!!)
Examples- Find the mass (grams) of one mole of each of the following:
1 mole of Magnesium = ________ grams
1 mole of Sodium Chloride (NaCl) = ________ grams
1 mole of Sulfur Trioxide (SO3) = ________ grams
&copy;Modeling Instruction Program 2008
1
U5-Counting v2.1
1 mole of Magnesium Phosphate (Mg3(PO4)2) = _____________ grams
Putting Molar Mass to Use!
Examples:
Find the mass of 2 moles of NaCl.
Find the mass of 6.7 moles of SO3.
If you have 184 grams of H2O, how many moles do you have?
If you have 675 grams of copper, how many moles of copper do you have?
Molar Volume:
If you have 2.7 moles of water at STP, how many liters do you have?
If you have 78.2 liters of carbon dioxide at STP, how many moles do you have?
Calculate the volume of each of the following quantities.
1. 0.100 moles of KI
2. 2.55 mole Cu2CrO4
3. 1.95 mole HNO3
Calculate the number of moles for each of the following volumes.
1. 1,500L of KClO
2. 200 L HC2H3O2
3. 75 L of NaOH
Unit 8 Worksheet 1: Molar Mass/Particle Practice
Part A.
1.
What is the mass of one mole of lithium?
2.
What is the mass of one mole of calcium?
3.
What is the mass of one mole of silver?
4.
What is the molar mass of one mole of fluorine, F2?
5.
What is the molar mass of one mole of KBr?
6.
What is the mass of 4 moles of lithium?
7.
What is the mass of 7 moles of strontium?
8.
What is the mass of 2 moles of KBr?
9.
What is the mass of 7 moles of beryllium sulfide (NaCl)?
10.
What is the mass of 5 moles of hydrochloric acid (HCl)?
Part. B Calculate the moles present in:
1) 2.00 grams of H2O
4) 8.76 grams of NaOH
5) 26.0 gram CaCl
2) 75.57 grams of KBr
3) 100. grams of KClO4
6) 5.08 gram XeF4
Part C
Calculate the number of particles in each of the following quantities:
1) 3.00 mole H2
2) 3.27 mole O2
3)
3.00 mole Zr
4)
3.27 mole Zn
5)
0.000300 mole Au
Part D
Calculate the number of moles in each of the following quantities:
1) 6.02 x 1023 particles of H2O
2) 3.60 x 1024 particles of Cl2
3) 9.99 x 1032 particles of HBr
4) 2.97 x 1021 particles of Zn
&copy;Modeling Instruction Program 2008
3
U5-Counting v2.1
WORKSHEET #2: 1 AND 2 STEP MOLAR CONVERSIONS
Part A: 2 step problems
1. Determine the number of H2O molecules in 3.26 g of H2O.
2.
Determine the mass of 7.92 x 1019 CO2 molecules.
3.
Calculate the number of O2 molecules in 35.5 g O2.
4.
Determine the mass of 8.43 x 1025 molecules of hydrogen phosphate (H3PO4)
5.
Calculate the number of liters that 11.3 g of NaHCO3 occupy.
Part B: 1 and 2 step problems
1. Calculate the number of molecules in 2.52 moles of H2SO4.
2. Determine the mass of 2.52 moles of H2SO4.
3. How many moles are present in 5.46 g of MgO?
4. Determine how many liters of ammonia (NH3) are present in 3.56 g of ammonia.
5. Determine how many grams of ethanol (C2H5O) are present in 2.38 x 1026 molecules.
6. Calculate the number of moles of ammonium phosphate ((NH4)3PO4) that contain 8.63 x 1021 particles.
*Challenge Problem* Determine the number of H atoms in 21.4 g of C6H12O6.
Worksheet #3: Empirical and Molecular Formula Worksheet
Percent to Mass  Mass to Moles  Divide by Small  Multiply ‘till whole
STEPS
STEPS
Example problem when % composition is given:
A compound contains 63.52% iron and 36.48% sulfur. Find empirical
formula.
Example problem when GRAMS are given:
A 10.15 g sample of a compound is known to contain only P and O.
When it decomposes, 5.717 g of oxygen is yielded.
Practice:
1. Quantitative analysis shows that a compound contains 32.38% sodium, 22.65% sulfur, and 44.99% oxygen. Find the
empirical formula of this compound.
2. A compound is analyzed and found to contain 36.70% potassium, 33.27% chlorine, and 30.03% oxygen. What is the
empirical formula?
3. Analysis of 20.0 g of a compound containing only calcium and bromine indicates that 4.00 g of calcium are present.
What is the empirical formula of the compound formed?
4. Determine the empirical formula of the compound that contains 17.15% carbon, 1.44% hydrogen, and 81.41%
fluorine.
STEPS
MOLECULAR FORMULA EXAMPLE: The empirical formula of a compound of
phosphorus and oxygen was found to be P2O5. Experimentation shows that
the molecular mass of this compound is 283.89 g/mol. What is the
compound’s molecular formula?
1. A 60.00 g sample of tetraethyl-lead, a gasoline additive, is found to contain 38.43 g lead, 17.83 g carbon, and 3.74 g
hydrogen. Find its empirical formula. If the molecular formula has a mass of 180.00 g, find the molecular formula.
Empirical
Molecular
2. A 170.00 gram sample of an unidentified compound contains 29.84 g sodium, 67.49 g chromium, and 72.67 g oxygen.
What is the compound’s empirical formula? If the molar mass of the molecular formula is 680.00g, find the molecular
formula.
Empirical
Molecular
3. Find the empirical formula of a compound found to contain 26.56% potassium, 35.41% chromium, and the remainder
oxygen. If the molecular formula has a mass of 1,470.00 grams, what is the molecular formula?
Empirical
Molecular
Unit 8 Review
1. What is the molar mass of MgCl2?
2. What is the molar mass of Li2CO3?
3. What is the molar mass of Ni(NO3)2?
4. How many moles are in 32.0 grams O2?
5.
How many moles are in 10.0 grams V2?
6.
How many particles are in .55 mole Kr?
7. How many atoms are in 0.100 mole Ni?
8. How many atoms are in 0.00550 mole Au?
9. How many moles are in 8.76 x 1028 particles of NaCl
10. How many moles are in 7.11 x 1023 particles of C6H12
11. How many moles are in 146 grams of CuSO4?
12. A chemistry experiment requires 2.00 moles of Ca(ClO3) 2. How many grams of Ca(ClO3) 2 are needed?
13. What is the mass, in grams, of one mole of iron (III) sulfate, Fe2 (SO4) 3?
14. How many moles of CO are in 3 liters of the gas at STP?
15. What is the volume of 2.00 moles of oxygen gas (O2) at STP?
16. How many molecules are in 23.0 g of H2SO4?
17. How many gold atoms are contained in 0.850 grams of gold?
18. What is the percent by mass of sulfur in copper sulfide, CuS?
19. What is the percent by mass of C in Ca(CN)2 ?
20. If the empirical formula for a compound if NO2 and its molecular mass if 92 grams, what is the molecular
formula?
21. A compound is found to contain 29.1 grams of sodium (Na), 40.5 grams of sulfur (S), and 30.4 grams of oxygen
(O). What is the empirical formula of the compound?
22. A compound is found to contain 7.20 grams of carbon (C), 1.20 grams of hydrogen (H), and 9.60 grams of oxygen
(O), and to have a molar mass of 150 grams/mole. What is the molecular formula of the compound?
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