Physical Organic Chemistry Summer Assignment 2017

The summer assignment for PO Chemistry reviews the topics of Lewis dot structures, polarity and molecular orbitals that were covered extensively in Intermediate Chemistry. These topics will be used again and again throughout Physical Organic Chemistry, so it is important that you become even more comfortable with them over the summer and early in the new school year. To that end, the summer assignment requires you to complete three practice worksheets (Summer Assignment Sheets 1 thru 3). To assist your review of these topics, the shared folder also contains pdf copies of the relevant sections from chapters 1 and 2 of the Physical Organic Chemistry textbook. All of the worksheets and textbook sections can be found in the shared Google folder (https://goo.gl/kRy1zh). The content covered by these worksheets will be reviewed in the first couple of classes in September and, while the worksheets themselves will not be graded, the content will be assessed on the first quiz of the year most likely during the second week of school. Again, all of these topics were covered in Intermediate Chemistry so the material should be familiar. Relevant Sections of Textbook: 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 1.10, 2.1, 2.2

https://goo.gl/kRy1zhhttps://goo.gl/kRy1zh

AP Stoichiometry Problems -- 1

1. Determine the empirical formula for a compound which contains 14.52% C, 1.828% H, 64.30% Cl

and 19.35% O.

2. What is the mass of one fluorine atom? {3.16 x 10-22 g}

3. What is the percentage of carbon in glycine, C2H5NO2? {32.0%}

4. How many moles of potassium are in 10.0 g of K3PO4? {0.141 mol}

AP STOICHIOMETRY PROBLEMS 2 -- GASES

R = 0.08206 L atm/mol deg = 8.314 L kPa/mol deg; 1 atm. = 760 torr

1. Calculate the density, in g/L, of gaseous silicon tetrachloride at 85 C and 758 torr. {0.904 atm}

2. What is the molecular weight of a gas, 1.12 g of which occupies 750 mL at 19 C and at a pressure

of 96.5 kPa? {5.76 g/L}

3. Consider a 2.50 L container in which 1.11 g of carbon reacts to form carbon monoxide.

2 C + O2 2 CO

What is the pressure of the carbon monoxide, measured in atmospheres at 25 C? {38 g/mol}

AP Stoichiometry Problems -- 3

1. How many grams of magnesium oxide are formed from the reaction of 4.00 102 g of magnesium

with 0.382 L of oxygen at a pressure of 5.00 kPa and a temperature of 32 C? The reaction is:

{3.4 x 10-9 g}

2 Mg(s) + O2(g) 2 MgO(s)

2. Lead(II) nitrate reacts with a chloride solution to form lead(II) chloride.

Pb(NO3)2 + 2 Cl PbCl2 + 2 NO

3

How many grams of lead chloride are formed when 1.50 g of lead nitrate is added to 85.0 mL of a

0.135 M solution of calcium chloride (CaCl2)? {1.26 g}

3. A student adds zinc chloride to a sodium phosphate solution forming zinc phosphate.

3 ZnCl2 + 2 Na3PO4(aq) Zn3(PO4)2 + 6 NaCl(aq)

What is the theoretical yield of zinc phosphate in this reaction when 30.0 g of zinc chloride reacts

with a solution containing 22.2 g of Na3PO4? {26.1 g}

AP STOICHIOMETRY PROBLEMS 4 -- PARTIAL PRESSURES

R = 0.08206 L atm/mol deg = 8.314 L kPa/mol deg; 1 atmosphere = 760 torr = 101.3 kPa;

at 25 C the vapor pressure of water is 23.8 torr.

1. A 2.50 g sample of potassium chlorate, KClO3, is decomposed by heating

2 KClO3 2 KCl + 3 O2

What is the volume of the oxygen which is given off, measured wet at 25 C and 748 torr? {0.786 L}

2. How many grams of potassium chlorate are needed to make 550 mL of oxygen, measured wet, at

760 torr and at 25 C? {1.8 g}

3. Assume that 185.0 g of F2 and 4.00 moles of Xe are contained in a flask at 0 C and 2.50 atm.

a) Calculate the volume of the flask and the partial pressure of each gas. {V=79.5 L}

b) If 24.6 g of Li is introduced into the flask, a violent reaction occurs in which some of the fluorine

is consumed and solid LiF is formed. Calculate the total pressure of the gases present after the

reaction has occurred and the temperature has returned to 0 C. {2.00 atm}

AP Stoichiometry Problems 5 -- Simple Mixtures

1. An impure sample of sodium formate weighs 0.964 g. When the sample is mixed with sulfuric acid,

the sodium formate reacts to form carbon monoxide as shown below:

2 HCOONa + H2SO4 2 CO + 2 H2O + Na2SO4

The carbon monoxide which is formed measures 242 mL when collected over water at 752 torr and

22.0 C. (The vapor pressure of water at 22 C is 19.83 torr.) Calculate the percentage of sodium

formate in the original mixture. {67.9%}

2. A 2.15 g sample of a metal chloride, MCl2, reacts with excess silver nitrate solution to give 3.50 g

of AgCl.

2 Ag+ + MCl2 2 AgCl + M2+

What is the percentage of chloride in the original sample? What is the atomic mass of the metal?

{59.7%; 105 g/mol}

Name:_________________________________

AP CHEMISTRY PROBLEM SET 1

For purposes of consistency, everyone should use R = 0.08206 L atm / mol K

1. Element X reacts with oxygen to produce X2O3. In an experiment it is found that

1.0000 g of X produces 1.1XXX g of X2O3. What is the molar mass of X?

2. a) A compound contains only carbon and hydrogen. A 0.857 g sample

is burned in oxygen to give 1.45 L of carbon dioxide, measured dry at

98.0 kPa and 20.0C. What is the compounds empirical formula?

b) What would be the volume of the carbon dioxide if it were collected wet at

2X.XXC (still with the same ambient pressure). Assume that the vapor pressure of

water is X.XX kPa at that temperature.

3. Ferric ion reacts with sulfide according to the reaction:

2 Fe3+(aq) + 3 S2

(aq) Fe2S3(s)

An iron solution is made by dissolving 1.25 g of ferric sulfate, Fe2(SO4)3, in XXX mL of water. (Assume the

volume of the liquid remains constant.) A sample of this solution containing 12.0 mL was mixed with

18.0 mL of 0.113 M sodium sulfide (Na2S) solution.

a) How many grams of ferric sulfide are formed?

b) How many sulfur molecules (S8) would be formed by decomposing the ferric sulfide?

c) If the sulfur molecules in (b) were vaporized and allowed to fill a 780. mL

container at 550.C, what would be the pressure of the sulfur in atmospheres?

4. A non-stoichiometric compound NaWOn is analyzed and found to contain 7X.XX%

tungsten. What is the value of n? (Since the compound is non-stoichiometric, n

does not need to be an integer.)

5. An aspirin tablet weighs 2.00 g. Part of the tablet is made of aspirin, C9H10O3, and part of the tablet is

unreactive filler. Combustion of aspirin goes according to the following reaction:

C9H10O3 + 10 O2 9 CO2 + 5 H2O

The combustion of an aspirin tablet produces 1.XXX L of carbon dioxide, measured

dry and at 100.0 kPa and 22C. What is the percentage of aspirin in an aspirin

tablet?

n =

6. Consider the combustion of aluminum in oxygen:

4 Al(s) + 3 O2(g) 2 Al2O3(s)

Suppose 6.75 g of aluminum is allowed to react with X.XX L of oxygen, measured at

25C and 1.02 atm. What is the mass of the aluminum oxide which is produced?

7.

A mixture containing KClO3, KHCO3, K2CO3 and KCl was heated, producing CO2, O2 and H2O according to

the following equations:

2 KClO3(s) 2 KCl(s) + 3 O2(g)

2 KHCO3(s) K2O(s) + H2O(g) + 2 CO2(g)

K2CO3(s) K2O(s) + CO2(g)

The KCl does not react. If 1XX.X g of the mixture produced 1.XXX g of H2O, 13.20 g of CO2 and 4.00 g of

O2, what was the composition (in percent) of the original mixture? Fill in your answers below.

KClO3 = ________% KHCO3 = ________% K2CO3 = ________% KCl = ________%

-1-

Stoichiometry and Gas Laws 1 1. What is a Mole?

Stoichiometry problems are based on moles, so lets start with that. For our purposes the number of

moles in a sample can be calculated in four different ways.

1. A mole is 6.02 x 1023 molecules (or atoms or ions) of something. This is Avogadros Number.

How many moles are equal to 1000 molecules of carbon dioxide?

1000 1

6.02 1023= 1.66 1021

2. A mole is the molar mass of something expressed in grams.

How many moles are in 2.56 g of carbon dioxide?

2.56 1

44.01 = 0.0582

3. The number of moles of a gas is calculated using the ideal gas law PV = nRT. Here P is the pressure;

V is the volume, typically in liters; n is the number of moles; R is the gas constant; T is the

temperature, in Kelvin not Celsius. The value of R, which depends on the units of pressure and volume,

will be given to you. However, the most common values are 0.08206 L atm/mol K and

8.314 L kPa/mol K.

How many moles of carbon dioxide occupy 2.55 L at 25C and 102.3 kPa?

=

=

102.3 2.55

8.314 298 = 0.105

For the very important case of 0C and 1 atm pressure, referred to as standard temperature and pressure

or STP, one mole of gas occupies 22.4 L. This is referred to as the molar volume.

4. For a solution, the number of moles is equal to the molarity times the volume in liters.

How many moles of chloride are in 260. mL of 0.120 M CaCl2?

moles = 2 M V = 2 0.120 M 0.260 L = 0.0624 moles

2. Simple Mole Calculations

Empirical Formula

This is the