AP Chem Summer Worksheet 2012: page 1
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Check the Website for Review Hints (% Composition, Empirical Formulas), brief instructions
(hydrates, Volume conversions) and a pdf file with full answers.
http://centralhighchem.com/AP_Chem_1st/WelcomeAPChem.html
Follow Links to the Summer 2012 Worksheet info
Chemical Formulas and names
1. Give the formula for each compound.
a. Nitrogen dioxide! ___________________!
d. Potassium acetate! _____________________
b. Tin(II) hydroxide! ___________________!
e. Lead(IV) oxide!
_____________________
c. Sodium phosphate!___________________!
f. Disulfur trioxide! _____________________ !
2. Name each compound.
a. Mg(CN)2 !
____________________ !
d. NiCO3! ____________________________
b. Ba(ClO3)2!
____________________!
e. Cl2O!
____________________________
c. Fe(OH)3!
____________________!
f. N2O5!
____________________________
3. Give the formula for these acids!
Name these compounds as acids
a. Hydroiodic acid! ______________!
d. HClO!
___________________________
b. Nitrous acid!
______________!
e. HC2H3O2! ___________________________
c. Phosphoric acid! ______________!
f. HF!
___________________________
+
–
g. Sodium ascorbate is Na C6H7O6 . Name HC6H7O6 as an acid _______________________
h. Citric acid is H3C6H5O7. What is the formula for sodium citrate? _______________________
(1a. NO2; b. Sn(OH)2; c. Na3PO4; d. KC2H3O2; e. PbO2 f. S2O3 ; 2. a. Magnesium cyanide; b. Barium chlorate; c. Iron
(III) hydroxide; d. Nickel(II) carbonate; e. Dichlorine monoxide; f. Dinitrogen pentoxide; 3. a. HI; b. HNO2;
c. H3PO4; d. Hypochlorous acid; e. Acetic acid; f. Hydrofluoric acid; g. ascorbic acid; h. Na3C6H5O7 )
Density, Conversions (See web site for Volume Conversion hints)
4. You find a gold ingot that fell off an armored truck in the street. It measures 10.0 cm by
0.0350 m by 50.0 mm. !
a. What is the mass of the bar? (assuming it really is gold) (Hint: Change all to cm first) ! (3380 g)
!
b. If gold costs $15,000 a kilogram, how much is the ingot worth?!
c. Do you return the ingot?
d. How many gold atoms are in the bar?!
($50,700)
(1.03 x 1025)
5. A pre- 1982 penny contains 3.08 g of Cu. If you flatten a penny to a 5.00 cm diameter, how thick
would it be (in µm)?!
(1.75 x 10–2 cm, 175 µm)
6. A gold atom has a “covalent radius” of 0.134 nm. If you consider it a sphere (4πr3/3) what is its
volume in nm3 and m3?!
(1.01 x 10–2 nm3, 1.01 x 10-29 m3)
! !
Page 2
7. a. A mini marshmallow is a cube that measures about 1 cm on a side. How many km3 would
be the volume of a mole of mini marshmallows? (change cm to km first)!
(6.02x 108 km3)
b. If these mini marshmallows were spread out over the United States, how deep a pile would
they make? Assume the US measures 4000 km by 2000 km. (V = l x h x d)!
(75 km)
Gas conversions, Gas Law Review, STP: !
PV=nRT!
P1V1 = P2V2
! 22.4 L = 1 mol gas at STP, R = 0.0821 L atm /mol K!
T1!
T2
****If you know Pressure, Temp and Volume of a gas, you can calculate number of moles!!!!
8. 400 mL of a gas has a mass of 0.300 g at 30°C and 0.900 atm. Calculate its formula weight.
(hint: calculate moles, then g/mol) "
(20.7 g/mol)
9. Liquefied natural gas (LNG) is mainly methane, CH4. You’ve invested in 250 kg of LNG
because you hear fuel oil prices are going up. Now you have to store it. How big a tank
would you need to store the CH4:
a. As a liquid at –164°C and 1 atm pressure (density = 415 g/L) !
(602 L)
b. As a gas at 25.0°C and 30.0 atm pressure!
(1.27 x104 L)
10. a. In an underwater environment, 620 kilograms of O2 is needed to provide a pressure of
0.70 atm (at 25°C) for a room that is 10.0 m wide by 15.0 m long. How tall is the room?
! (Hint: 1000 L = 1 m3)!
(4.5 m)
!
b. You want to fill another room (Volume 6.30 x 104 L ) with Hydrogen gas at a partial pressure
of 1.50 atm at 25.0 °C. You have hydrogen available in 55.0 Liter tanks at a pressure of 135 atm
at 0.00 °C. How many tanks do you need? !
(12 tanks)
Combustion Review: Write the complete, balanced equation for these reactions
11. a. Complete Combustion of Pentene gas, C5H10
b. Combustion of ethanol (C2H5OH) in excess oxygen
c. Combustion of Propane gas (C3H8) in limited oxygen
AP Chem Summer Worksheet 2012: page 3
% Composition, Empirical Formulas (See Example on web site )
1. a. A compound containing just Copper and Bromine is heated to drive off the Bromine. Here is
the data from the experiment. Calculate the % composition by mass of the compound.!
! Empty crucible: !
21.50 g!
(45.0% Cu, 55.0 %Br)
! Crucible + compound !
25.50 g!
! Crucible + copper residue !23.30 g
!
b. What is the formula and name of the compound? !
(CuBr, Copper(I) Bromide)
2. a. A 2.000 g sample of a compound (made of C’s, H’s and O’s) was found to contain 0.818 g of
Carbon and 0.092 g of Hydrogen. a. What is the % composition by mass of the compound?
! !
(40.9 %C, 4,6 %H, 54,5% O)
!
b. Determine the empirical formula of the compound.!
!
c. Another 3.50 g sample of this compound was vaporized and occupies a volume of 460 mL at
1.05 atm pressure and 25°C. What is the molecular weight of the gas? !
(177 g/mol)
!
d. What is the molecular formula of the compound?!
!
e. How many Carbon Atoms are in 75 milligrams of this compound? "
(C3H4O3)
(C6H8O6 or Ascorbic acid, Vitamin C)
(1.54 x1021 C atoms)
Hydrates (New! See Example on web site)
3. A Hydrate is a compound that contains water as part of its crystal structure. Give the name or
formula for these hydrates: For example: FeSO4•7 H2O is Iron(II) sulfate heptahydrate
a. Na2SO4•10 H2O! ____________________ !d. potassium sulfite pentahydrate !
____________
b. CoCl2• 2 H2O!
____________________ !e. nickel (II) phosphate octahydrate! ____________
c. CrSO4• 7 H2O!
____________________! f. Iron (III) chloride hexahydrate!
____________
(a. Sodium sulfate decahydrate; b. Cobalt(II) chloride dihydrate; c. Chromium(II) sulfate heptahydrate;
d. K2SO3•5 H2O; e. Ni3(PO4)2 •8 H2O; f. FeCl3•6 H2O)
4. a. What is the % by mass of water in Epsom salts: MgSO4• 7 H2O !
(51.2%)
b. If you heat 6.00 g of Epsom salts, how much water is lost? What is the final mass of the
remaining anhydrous (without water) compound?!
(3.07 g H2O, 2.93 g)
Page 4
5. 3.50 g of a Copper(II) chloride hydrate is heated. The final mass of the anhydrous compound is
2.78 g. a. What is the % water in the hydrate? !
(20.6%)
b. What is the formula and name for the hydrate? "
(CuCl2•2H2O, Copper(II) Chloride dihydrate)
Combustion Analysis (NEW!! See website for example)
6. a. 3.50 g of an organic compound (C’s and H’s) is burned completely and produces 11.00 g CO2
and 4.50 g H2O. What is the % composition by mass of this compound? ! (85.7 %C, 14.3% H)
! b. What is the empirical formula of the compound? !
(CH2)
! c. 0.255 g of this gaseous compound has a volume of 135 mL at a temperature of 50.0°C and a
pressure of 0.900 atm. What is the formula weight of the compound?!
(55.7 g/mol)
!
d. What is the molecular formula for the compound?!
(C4H8)
7. 1.25 g of a sweet tasting liquid (made of C’s, H’s and O’s) is burned and produces 1.77 g CO2
and 1.09 g H2O. Another 0.400 g of the liquid is then evaporated to form a gas with a volume of
1.70 L at 150°C and 0.130 atm pressure. What is the empirical and molecular formula of the
compound? "
(C2H6O2, Ethylene glycol {antifreeze})
8. A parent asks you to analyze a drink their child says contains a powerful drug (made of C’s,
H’s, O’s and N’s). 2.75 g of the compound is burned and produces 4.99 g of CO2, 1.28 g of H2O
and 2.61 g of NO2. Then you sublimate 0.200 g of the compound, forming 410 mL of gas at
200°C and 0.100 atm pressure. What is this drug? Should the parent be concerned?
!
( C8H10N4O2, caffeine)