Exam 2: Monday 21 October 2013. All material from 25 September mini-quizzes 11-16 Exercises #3a,b Reading pp 2-8; 112-114, 384-395; (396-406). English-metric conversions (2 pts each/6 pts total) Conversion factors 1 meter = 1.094 yards= 3.281 feet 1 inch=2.54 cm=25.4 mm
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Exam 2: Monday 21 October 2013
Conversion factors 1 meter = 1.094 yards= 3.281 feet 1 inch=2.54 cm=25.4 mm
1 kilometer= 0.622 miles 1 liter=1000 mL = 0.275 gallons
1 mile=5280 feet =1760 yards 1 lb =454 g = 0.454 kg =16 oz
12 in = 1 foot
2.2. Metric-metric symbols and conversions (16 pts)
Ex.
Ex.
200 g = ?? kg
2.3. unknown metal density determination (4 pts)
See density lab and review metal density determination
2.4 egg arithmetic (2 pt each/8 pts total))
A dozen monstrously large eggs from Aldi’s weighs 2000 g. Assuming 1 dozen =12 count:
Ex.
Assuming that a mole count= 6*1023 and the gram atomic masses:
C=12 g/mol O=16 g/molH= 1 g/mol
Ex.
Glucose has the molecular formula C6H12O6 . What is its’ molecular weight ? ______g/mol
How many molecules of glucose are in 9 grams of glucose ? ______ molecules glucose in 9 grams
Ex.
2.6. Stoichiometry Problems (`Body Parts’): Show work !(5 pts each/25 pts total)
The molecular mass of dynamite=TNT (C7H5N3O6) is 227 g/mol.
Given the atomic masses for C=12 g/mol, H = 1 g/mol, N = 14 g/mol O=16 g/mol
Ex.
2.7. % Composition problems and combustion problems ( 3 pts each/9 pts total)
Ex.
Empiric formula=:____________________
Ex. CxHy is burned to form 4.4 g CO2 and 1.8 g H2O. What is the empiric formula of CxHy ?
2.8 Reaction Balancing (2 pt each/ 6 pts total)
Balance these reactions:
___ C2 H6 + ___O2___CO2 + __H2O
Ex.
2.8 Naming ( 1 pt/name; 4 pts total) Review Stock namingmethod presented in lab
Given: acetate = C2H3O2-1phosphite = PO3-3 carbonate = CO3-2nitrate = NO3-1
Use the Periodic Table provided to name or determine the formula of the four compounds below:
Ex.
CuCO3 name=_____________________
2.9 Simple Reaction Stoichiometry Problem (maybe…) (3 pts)
Given the balanced reaction:
2C8H18 + 25O2 16CO2 + 18H2O
MW 114 32 44 18 g/mol
How many grams of water form when 0.061728 mol C8H18 are burned ? (show work or no credit)
Ex.
2.7. % Composition problems ( 4 pts each/8 pts total)
Ex.
Empiric formula=:____________________
2.8 Reaction Balancing (2 pt each/ 6 pts total)
Balance these reactions:
___ C2 H6 + ___O2___CO2 + __H2O
Ex.
2.8 Naming ( 1 pt/name; 4 pts total) Review Stock namingmethod presented in lab
Given: acetate = C2H3O2-1phosphite = PO3-3 carbonate = CO3-2nitrate = NO3-1
Use the Periodic Table provided to name or determine the formula of the four compounds below:
Ex.
CuCO3 name=_____________________
2.9 Simple Reaction Stoichiometry Problem (maybe) (3 pts)
Given the balanced reaction:
2C8H18 + 25O2 16CO2 + 18H2O
MW 114 32 44 18 g/mol
How many grams of water form when 0.061728 mol C8H18 are burned ? (show work or no credit)
Ex.
A similar text book problem to try:
Page 418 Problem 51
Propane is a common hydrocarbon gas used for heating rural American homes. Complete combustion of a sample of propane produced 2.641 g CO2 and 1.442 g H2O. What is the empiric formula for propane ? (also called LNG=liquid natural gas)
Answer: C3H8
Then: classical chemical methods decompose and capture elements
+ Balance
+ Chemical Finesse
Glassware
1750
1960
5870 HP GC-MS
ASC Instrumentation lab has three of these (~80 k$ each)
Gas Chromatograph- Mass Spectrometer
Mass Spec (CSI !)
Where’s the analyst in charge ??
Mass spectrum of cocaine
MS-NIST Data Base Match Output
Most likely compound ranked by computer search engine (63.3%=P)
Example #1:
Elementcombustion
2
2
Cu +O2 CuO
Balanced !!!!
Example #2:
Organic combustion
Balanced…at last !!!!
C3H8+ O2 CO2+ H2O
5
3
4
Propane=LNG
Liquid Natural Gas
Helpful hint: first balance elements that appear in a single compound opn both reactant and product sides.
Slightly trickier balancing…the odd/even oxygen dilemma
Internal combustion reaction
2
16
__C8H18 + __O2 __H2O + __ CO2
25
18
Octane = gasoline
balanced
More in-class equation balancing practice
4
1
__H3PO3 ___H3PO4 + ___PH3
3
2
9
2
6
__As2S3 + __O2__As2O3+ __SO2
Helpful hint: first balance elements that appear in a single compound opn both reactant and product sides.
More in-class equation balancing practice (continued)
1
3
4
__Ca3(PO4)2+ __H3PO4 __Ca(H2PO4)2
6
6
1
__Fe2(SO4)3 +__NH3 + __H2O __Fe(OH)3 + __ (NH4)2SO4
3
2
Helpful hint: balance odd/even pairs of elements appearing in single compound on both reactant and product sides, first.
Sample of Typical Reaction stoichiometry problems
C3H8+ 5O2 3CO2+ 4H2O
BALANCED
Example 1: (reactant product)
Given 16 grams of O2 predict the maximum molecules of CO2 that can form.
Typical Reaction stoichiometry problems (cont.)
C3H8+ 5O2 3CO2+ 4H2O
Example 2: (limiting reactant product)
Given 1 gram of O2 and 1 gram of C3H8, what is the maximum weight of H2O we can make ?