ap chemistry summer packet 2019 - cmit...

AP CHEMISTRY SUMMER PACKET 2019

Instructor: Fethi Ozdem [email protected]

Dear students,

I feel extremely delighted that you have decided to take Advanced Placement Chemistry! This course is designed to give you a more complete experience of chemistry that will prepare you for the AP Chem Exam during next May and would also provide you with enriching college level experience. The only way to complete all the topics in this rigorous course is to move at a very rapid pace. I will complete all the portions of the course shortly after the end of the third quarter so we can begin reviewing for the exam. Therefore, it is critical for all students to complete the Summer Assignment to be ready to get after it in the fall.

The Commitment

If you are taking the AP Chem course, you have already enjoyed success in your academic career. Taking a course such as AP Chem will be very different than courses you have taken in the past. It will involve a level of work and commitment that you may not have experienced before.

Regardless of who teaches this course, it always follows the same pace, has the same workload, and the same difficulty level. There is a very specific amount of material that must be covered for the AP Test and there is no time to re-teach or slow down if some students are falling behind. We absolutely must be ready for the AP Test in May. You must accept the fact that you will have significant work outside of class and will need to get help on assignments and lab work.

You must complete the summer assignment that follows here. We will have a test on this material on the First day of class. To save some valuable time later in the course, everyone needs to be ready to go. Carefully read the information on the summer packet on the pages that follow.

Please get started early and work consistently. Your goal must be to master the concepts and retain them. For this repeated practice is a must. Please remember that you will not be allowed to use the ions’ charts and the periodic tables containing color codes and names any more in your AP class. All research on human memory shows us that frequent, short periods of study, spread over long periods of time will produce much greater retention than long periods of study of a short period of time.

We are going to have an exciting, challenging and fun year. I look forward working with you all next year. I hope you

have a great summer. If you do have any question, please feel free to email me. I cannot promise to check it every

day, but I will get back to you as soon as I can.

Best of luck to you all

Fethi Ozdem

mailto:[email protected]

AP Chem Summer Packet 2019

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The Summer Review Packet Checklist

____ Email: email me your name stating that you are taking AP chem course this year. Due: June, 30 ____ Part 1: AP Chem Exam Overview Submit by email attachment Due: First day of the school ____ Part 2: Review and memorize “What to memorize” Test: First day of the school ____ Part 3: Review and complete Chem “Language”

Submit by email attachment Due: First day of the school Test: First day of the school ____ Part 4: Review and complete Math Skills Test: First day of the school ____ Part 5: Review and complete Key Concepts of First Unit Submit by email attachment Due: First day of the school Quiz: First week of the school

Part 1: AP Chem Exam Overview I want you to spend some time familiarizing yourself with the exam...much of the course will be geared to your preparation for it, so let’s make sure you know what you’re getting into. A brief explanation about AP chemistry is given below. For more information please visit

http://apcentral.collegeboard.com/apc/public/courses/teachers_corner/2119.html for Course Overview, Full

Course Description, and Lab Manual.

You may need to register and log in to answer these questions. Most will be found in the chemistry section. You are responsible for finding your own way around the site, but it is important to download the AP chemistry course description. It answers all your specific questions about what you need to do and know specifically for the chemistry test, including those on this sheet. You may want to refer to this document as we proceed throughout the year. On or before the first day of class submit, by email, your answers in with your name and the assignment title in the upper right-hand corner. Answer these questions in complete sentences on a separate page. 1. On what date did you gather the information below?

2. What is the date of the 2020 AP Chemistry exam (the one many of you will take)?

3. What are the two major parts to the exam? What percent of your total score does each count?

4. What are the types of problems will you be required to answer in the free response section?

5. Specifically where in the exam will you be allowed or not be allowed to use the following....

a. Calculator

b. Periodic table

c. Sheets with formulas and reduction potentials

6. Are there any examples of released questions available at the web site? Describe.

7. Is there anything new specified for this year’s chemistry exam?

http://apcentral.collegeboard.com/apc/public/courses/teachers_corner/2119.html


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AP Chemistry Exam Date: Thu, May 7, 2020, 8 AM Local

Learn about the fundamental concepts of chemistry including structure and states of matter, intermolecular

forces, and reactions. You’ll do hands-on lab investigations and use chemical calculations to solve problems. Note:

Save your lab notebooks and reports; colleges may ask to see them before granting you credit.

Course Content

The exam is 3 hours and 15 minutes long and includes 60 multiple-choice questions and 7 free-response

questions. A scientific or graphing calculator is recommended for use on Section II of the exam. No calculators are

permitted for use on Section I. Students are provided with the periodic table and a formula sheet that lists specific

and relevant formulas for use on the exam (given below)


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Part 2: What to memorize... 1. Specified Element Names and Symbols from the Periodic Table • Elements 1-38 • Ag, Cd, I, Xe, Cs, Ba, W, Hg, Pb, Sn, Rn, Fr, U, Th, Pu, and Am written correctly 2. Monatomic Ions (both those with one and those with multiple oxidation states) An extensive list is provided in this packet. 3. Polyatomic Ions and corresponding acids An extensive list is provided in this packet. 4. Colors of Common Ions An extensive list is provided in this packet. Remember: A mastery of the common ions, their formulas and their charges, is essential to success in AP Chemistry. Really, I mean it. If you learn this list of polyatomic ions, you just may do well in this course. If you don’t, you will surely encounter a great deal of difficulty. To learn “say aloud and write them over and over and over and over and over and over and over” until you got them. Flash cards might provide additional support. You are expected to be very familiar with all of these ions and the diatomic elements on the first day of class; your

FIRST DAY TEST will have ample number of questions on ions to check your mastery of this, along with other

concepts.


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Part 3: Chem language When you report to class in September, I want you to be prepared to speak “the language” of chemistry. For now that means knowing the names, charges, and formulas of common ions and the names and formulas of ionic compounds, covalent compounds, and acids. Review the following pages of instructions and complete the work that follows. We will have a test on the first day of class. Note: In studying, do NOT treat this as a one-time test. You will need to know these from memory in every quiz and test we take throughout the year.

HINTS: 1) “-ites” have one less oxygen than “-ates” (also “hypo” means even one less, “per” means one more)

2) The prefix “bi” or “hydrogen” indicates that you must add a H atom and increase the charge by one (in the positive direction).

3) Ions made from the halogens (Cl, Br, and I) differ only in the central atom (see chlorate and iodate as an example)

4) “thio” means sulfur.

Nomenclature Review

Forming binary ionic compounds

A. In a binary ionic compound the total positive charges must equal the total negative charges. Use the “Criss Cross Method”.

B. Ex. What ionic compound would form when calcium ions combine with bromide ions?! Use the steps to the Criss Cross Method:

1. Write the ions with their charges, cations are always first. Ca+2 Br-1

2. Cross over the charges by using the absolute value of each ion’s charge as the subscript for the other ion. Ca1Br2

3. Check to make sure the subscripts are in the lowest whole number ratio possible. Then write the formula. CaBr2


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Naming binary ionic compounds

A. Combine the names of the cation and the anion.

B. Example: BaBr2 is named barium bromide.

Naming binary ionic compounds that contain polyatomic ions

A. The polyatomic ions on your common ions list should be memorized.

B. The most common oxyanions – polyatomic anions that contain oxygen, end in –ate.

Oxyanions with one less oxygen end in –ite. For example:

NO3-1 is nitrate! SO4

2- is sulfate

NO2-1 is nitrite! SO3

2- is sulfite

C. Anions with one less oxygen than the –ite ion are given the prefix hypo-.

D. Anions with one more oxygen than the –ate ion are given the prefix per-.

ClO-1 is hypochlorite! ClO3-1 is chlorate

ClO2-1 is chlorite! ClO4

-1 is perchlorate

E. Naming compounds with polyatomic ions is the same as naming other compounds, just name the cation and then the anion. If there is a transition metal involved, be sure to check the charges to identify which ion (+1, +2, +3, +4 ….) it may be so that you can put the correct Roman numeral in the name.

Polyatomic Ions Ending in “ate”

Notes and Observations (see above table)

1. The individual locations of the elements in the table correspond to their relative locations on the periodic table.

2. The outside edges have ions that all end in “O3”.

3. The interior area has ions that all end in “O4”.

4. The charges of the ions become more positive as you go across a “period”.

5. For ions with the same root containing oxygen, the suffixes and prefixes are :

(Using chlorate as an example)

• Ions starting with “per” will have one more oxygen.

! Ex. ClO4-1 = perchlorate

• Ions ending in “ite” will have one less oxygen.

! Ex. ClO2-1 = chlorite

• Ions starting with “hypo” and ending in “ite” will have two less oxygens.

! Ex. ClO-1 = hypochlorite


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Naming binary molecular compounds A. With molecules, the prefix system is used.

B. The less-electronegative element is always written first. It only gets a prefix if it has more than one atom in the molecule.

C. The second element gets the prefix and the ending –ide.

D. The o or a at the end of the prefix is dropped when the word following the prefix begins with another vowel, for example monoxide or pentoxide.

Exercise 1 - Nomenclature: Simple Inorganic Formulas and Nomenclature

I. In the first column, classify each of the following as molecular (M) or ionic (I). In the second column, name each compound:


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II. In the first column, write the chemical formula (formula unit) for the compound formed between the two given elements. In the second column, write the name for the compound:


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Part 4: Math Skills Review When you report to class in August, I want you to have your basic math skills in order. You should have a scientific (graphing) calculator for this class (one that does logs and exponential notation.) However, you will not be able to use that calculator on many problems for course exams and on the multiple-choice part of the AP test. The purpose of this assignment is to make sure you can do basic math operations without your calculator. Read the attached math skills worksheet. Do the practice examples and worksheets.

Throughout the course, every answer must be expressed as a proper decimal or in proper scientific notation. The following examples are NOT allowed: 2/3 (no fractions change to 0.667); 23 x 10¯4 (improper coefficient- change to 2.3 x 10¯3); 1 x 10¯4.60 (improper exponent- change to 2.5 x 10¯5 ); 602000000000000000000000 (ridiculously long- change to 6.02 x 1023 )

Some notes on significant figures (significant digits, sig figs, or SF). There are two skills to learn in significant digits. They will be detailed more when you get back to school.

1) We will review how to determine the number of significant digits early in the year. For this worksheet assume that all digits given are significant.

2) In AP Chem you must be able to use the rules of calculation with significant digits.

These two rules are as follows (you must use the first on the scientific notation worksheet):

A) When adding or subtracting: Line up the decimals (in regular or in scientific notation). Find the number whose last digit is furthest to the left (the number with the highest ending place value.) Round your answer to this place value. ex. 23.2 + 5.6739 = 28.8739 = 28.9 (answer must stop in the tenths place because of 23.2)

ex. 2.3 x 10¯3 - 0.005 x 10¯3 = 2.295 x 10¯3 = 2.3 x 10¯3 (answer must stop in the 10¯4 place because of 2.3 x 10¯3) This rule will be very important in determining when approximations used to simplify problem solving are truly valid

B) When multiplying or dividing: Round your answer to the number of digits equal to the least number of digits in any of the factors. ex. 23 (2 digits) / 5672 (4 digits) = 4.1 x 10¯3 (2 digits) (This rule will not be important on the summer worksheets since you are asked to round everything to one digit)

As AP students, you are expected to have certain math skills. You should also be able to do the practice exercises on these sheets with little or no hesitation. I will not be teaching these skills with a specific lesson in class; instead I will assume that you have learned them on your own by the time we use them in class. If you cannot follow the math on the board, you will be more confused in class. If you cannot do it on your own, homework will be much more difficult. If you cannot do it on a test, you may not be able to answer certain questions where you are not allowed to use a calculator. So if you need to brush up, do the practice exercises and/or come for extra help.

Operations with numbers in scientific notation.

Multiplying: (needed for moles, wavelength / frequency / energy, much more)

step 1) multiply the coefficients (the leading number parts)

step 2) multiply the powers of 10. Hint: to do this add the exponents to get a new exponent

step 3) combine new coefficient and exponent and adjust the answer to proper scientific notation

Example: (4 x 10-2) (3 x 105)

step 1) 4 x 3 = 12; step 2) (10-2)(105) = 10-2+5 = 103; step 3) 12 x 103 = 1.2 x 104


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Dividing: (similar uses as multiplying)

step 1) divide the coefficients

step 2) divide the powers of 10. Hint: to do this subtract the exponents to get a new exponent

step 3) combine new coefficient and exponent and adjust the answer to proper scientific notation

Example: 1x104/3x107

step 1) = 0.333; step 2) = 104-7 = 10-3; step 3) 0.333 x 10-3 = 3.3 x 10-4

Solve the following without using a calculator. Round to 1 digit (significant figure, or SF)

1) 6x108 / 3x1010

2) 6x108 x 3x1010

3) 6x10-4 / 1.8x10-3

4) 1.8x108 / 3x1010

5) 7x108 / 6.3x1010

6) 4x108 x 5x10-6

7) 4x10-3 / 5x10-5

8) 6x10-7 x 9x104

9) 8x105 / 2x103

10) 3x10-5 / 8x10-2

11) 5x10-4 x 6x10-3

12) 6x1025 / 5x109

13) 7.2x108 / 1.2x10-4

14) 8x10-3 / 9x10-10

15) (9x103)2

16) 4*(3x106)2

17) 4*(2x10-3)3

18) 5*(4x10-7)3

Adding or subtracting in scientific notation: (for equilibrium problems, especially acid-base)

Note: numbers can only be added or subtracted in scientific notation if they have the same exponent! If they do not have the same exponent, one must be rewritten:

step 0) (if necessary) adjust the numbers so the exponents match

step 1) add or subtract the coefficients (sig figs are often important!)

step 2) keep the same exponent

step 3) combine new coefficient with exponent and adjust the answer to proper scientific notation

Example: 8.000 x 105 - 3 x 102 ---> step 0) 8.000 x 105 - 0.003 x 105

step 1) 8.000 - 0.003 = 7.997; step 2) power of ten = 105; step 3) 7.997 x 105

Sig figs are very important in this operation. Rule reminder: your answer can only go as far in place value as the least precise of the numbers you are adding or subtracting (the one whose last digit is “furthest left” or “has the highest place value.” Subtracting numbers of greatly different exponents is usually not significant:

Example: 6.00 x 10-4 + 3 x 10-7 ---> step 0) 6.00 x 10-4 + 0.003 x 10-4

step 1) 6.00 + 0.003 = 6.00; step 2) power of ten = 10-4; step 3) 6.00 x 10-4 (place value only to the hundredths)


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Solve the following without using a calculator. Answers are given to correct sig figs.

19) 2.00 - 3.00x10-2

20) 2.00 - 9.00x10-6

21) 6.00x10-7 + 9.00x10-6

22) 0.0100 - 2.00x10-4

23) 3.00x10-5 + 1.00x10-7

24) 8.45x109 + 3.00x103

25) 4.5x10-7 + 9.00x10-8

26) 7.56x1023 + 9.0x1022

27) 6.0x10-8 - 6x10-10

28) 2.4x10-5 + 1.0x10-7

Estimating roots of numbers in scientific notation: (needed for equilibrium problems)

The root of a number in scientific notation is equal to the root of the coefficient times the root of the power of 10.

example: √(4x10-10) = (√4) x (√10-10) = 2 x10-5

The root of the power of 10 can be found easily only if the exponent is divisible evenly by the root being taken (in the example above, the exponent, (-10) was divisible by the root, which is 2 for “square root”). If the exponent is not evenly divisible (as in √4x10-7), the number is adjusted so the exponent is lower but now divisible by the root...

example: √(4x10-7) = √(40x10-8) = (√40) x (√10-8) = 6.3 x10-4

You should be able to estimate the value of a square root to within a tenth or two... the value for √40 in this case must lie between 6 and 7 (62 = 36 and 72 = 49), but somewhat closer to 6.

Cubed roots are treated similarly:

example: 3√(4x10-7) = 3√(400x10-9) = (3√400) x (3√10-9) = 7.4 x10-3

Here the exponent is made divisible by the root, 3. 3√400 is estimated as described above... it must lie between 7 and 8 (73 = 343 and 83 = 512), but somewhat closer to 7. Obviously, an estimate of a cubed root is a bit harder mathematically than that of a square root (the numbers can approach 1000 instead of just 100), but since an exact estimate is not critical, this is still very doable. Any guess between 7 and 8 x10-3 is acceptable for this problem.

Practice: solve for x without a calculator (1SF)

29) x2 = 9x1010

30) x3 = 8x10-15

31) x2 = 5x10-8

32) x2 = 6x105

33) x2 = 4x10-15

34) x3 = 5x10-10

35) 4x3 = 1.08x10-4

36) 2x2 = 8x10-9

37) x3 = 5x10-11

38) 4x3 = 3x10-23

Estimating with logs (use mainly for pH’s).

You will only be expected to estimate with base 10 logs. Natural logs (ln) will also be used in this course, but they will generally not appear on the AP exam and you will not need to estimate their values. Since log functions are non-linear, you are primarily expected to recognize that a value lies within the proper order of magnitude (i.e., the pH is between 6 and 7, not between 7 and 8). However, within reason, you should also be able to distinguish between two possible choices that are in the same order, but only one of which makes sense (see below)


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Number to log: finding logs or “log(x)” ([H+] to pH):

What is the pH of a solution with [H+]=4x10-3 M? The pH is the negative log of [H+], in this case –log(4x10-3). To find a pH, you just find the log of the number representing [H+], then take the opposite. Since 4x10-3 lies between 10-3 and 10-2, the log is between -3 and -2 (meaning pH is between 3 and 2.) Note... since the log function is not linear, even though 4x10-3 is closer in value to 10-3, the log is closer to -2 (actually equaling -2.4). However, if the concentration is 9x10-10, since the value is very close to 10-9, the log will be very close to -9 (actual log = -9.05)

Log to number: powers of 10 or “10x” (pH to [H+]):

What is the [H+] of a solution with pH = 8.5? The answer is 10-8.5 M, however this answer is not in acceptable form. Since 10-8.5 lies between 10-8 and 10-9, it is bigger than 10-9. The actual value is 3.2x10-9 Note... since the log function is not linear, even though 8.5 is half-way between 8 and 9, in scientific notation 10-8.5 is closer to 10-9. A log of -7.1 (pH=7.1), however, should obviously correspond to a number closer to 10-7 than 10-8 (actual number or [H+] = 7.9 x 10-8).

Practice: Without using a calculator, circle the correct answer (check with a calculator)

What is the log of 9x10-4 M? -3.05, -3.95, -4.05, or -4.95

What number has log = 2.2? 9.3x101, 1.6x102, 9.3x102, or 1.6x103

What is the log of 2x108 M? 7.7, 8.3, 8.7, or 9.3

What number has log = -10.1? 7.9x10-9, 2.1x10-10, 7.9x10-10, 2.1x10-11, or 7.9x10-11

What is the pH of a solution with [H+]=7x10-9 M? 8.2, 8.8, 9.2, or 9.8

What is the [H+]= of a solution with pH = 2.9? 1.3x10-3 , 9.3x10-3, 1.3x10-2, or 9.3x10-2

Estimate the following values. Answers below. Make up your own practice if you want!

a) log (8.7x1012 M)

b) log (1.4x10-5 M)

c) 10-6.9

d) 104.8

Estimate the following values. Answers below.

e) pH = 3.4. What is [H+]?

f) [H+]= 6.13x10-6 M. What is the pH?

g) pH = 11.80. What is [H+]?

h) [H+]= 0.5 M. What is the pH?

Math Answers: Answers: 1) 2x10-2 2) 2x1019 3) 3x10-1 4) 6x10-3 5) 1x10-2 6) 2x103 7) 8x101 8) 5x10-2 9) 4x102 10) 4x10-4 11) 3x10-6 12) 1x1016 13) 6x1012 14) 9x106 15) 8x107 16) 4x1013 17) 3x10-8 18) 3x10-19 Answers: 19) 1.97 20) 2.00 21) 9.60x10-6 22) 9.8x10-3 23) 3.01x10-5 24) 8.45x109 25) 5.4x10-7 26) 8.65x1023 27) 5.9x10-8 28) 2.4x10-5 Answers: 29) 3x105 30) 2x10-5 31) 2x10-4 32) 8x102 33) 6x10-8 34) 8x10-4 35) 3x10-2 36) 6x10-5 37) 4x10-4 38) 2x10-8 a) 12.9 b) -4.9 c) 1.3x10-7 d) 6x104 e) 4x10-4 M f) 5.2 g) 2x10-12 M h) 0.3


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International System of Units (SI Units) A series of international conferences on weights and measures has been held periodically since 1875 to refine the metric system. At the 11th conference held in France in 1960, a new system of units known as the International System of Units (abbreviated SI in all languages) was proposed as a replacement to the metric system. The five of the seven base units for the SI system are given in Table 1—missing from the table are electric current (ampere) and luminous intensity (candela), units that aren’t of interest to us right now. You will need to memorize the base unit and its symbol for each of Tables 1 & 2 as they will be used extensively this year in AP Chem.

Strict adherence to SI units would require changing directions such as “add 250 mL of water to a 1-Liter beaker” to add 0.00025 cubic meters of water to an 0.001 m3 container. Because of this, a number of units that are not strictly acceptable under the SI convention are still in use. Some of the common non-SI units in common in use are in Table 2.

Note the following examples:

• “milli” means one-thousandth; so a milliliter (symbol: mL) is one thousandth of a Liter and it takes 1000 mL to make 1 L; therefore 1 L = 1000 mL

• “kilo” means one thousand; so “kilogram” (kg) means one thousand grams: 1 kg = 1000g. One millionth of a gram would be represented by one microgram (μg): 1 Pg = 10-6 g It takes one million micrograms to equal one gram: 106 μg = 1 g

• one centimeter (1 cm) is equal to 0.01 m because one cm is “one hundredth of a meter”: 1 cm = 0.01 m = 10-2 m


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Key Questions (Answer to the separate paper)

1. How many milligrams are there in one kilogram?

2. How many meters are in 21.5 km?

3. Is it possible to answer this question: How many mg are in one km? Explain.

4. a.) What is the difference between a Mm and a mm?

b.) Which is larger 1.0 Mm or 1.0 mm? Explain.

Dimensional Analysis (Factor-label method: Conversions Between Measurement Systems)

In scientific measurements, units usually follow the numerical value. When mathematically manipulating scientific measurements, you will often need to convert from one unit to another. When this is done, you must multiply what is given by one. In a conversion factor, what is in the numerator must be equivalent to what is in the denominator (otherwise, you’re not multiplying by one!). You must apply conversion factors such that the units cancel appropriately.

Therefore, you will constantly be asking the questions: “What units do I have? Is it in the numerator or in the denominator? What units can I convert to from what I have?”

Units you have but no longer want will be written in the conversion factor on the opposite

side of the division bar.

For example, if the units you have but want to convert from are in the numerator, those units will be put in the denominator of the conversion factor.


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Example 1. Using more than one conversion factor

By definition, 1 inch is equivalent to 2.54 centimeters, 1 foot is equivalent to 12 inches, and 1 mile is equivalent to 5280 feet. How many kilometers are in a mile?

Example 2. Conversion factor raised to a power

The density of isopropyl alcohol is 6.56 pounds per gallon. What is the density of isopropyl alcohol in grams per cubic centimeter? (1 kg = 2.205 lb, 1 gal = 3.785 L, 1 L = 1 dm3)


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Key Questions

6. What in the numerator of a conversion factor must be equivalent to what is in the denominator of the conversion factor. Explain why.

7. Consider the exercise: “How many seconds are there in 50 minutes?” Suppose it was solved in the following way:

a.) Is the answer reasonable? Explain.

b.) Comment on how the units were handled. What “rule” of the model (the factor-label method) was broken in the above solution?

Exercises

Instructions: Show your work using the factor-label method. Circle your answers and use correct units and significant figures for all questions—no work, no credit. Use the table of SI – English conversion factors on the inside back cover of your text as needed.

8. Perform the following unit conversions. Show your work in each case using the factor-label method. Circle your answers and use correct sig figs.

a.) 15.60 cm = ?? m b.) 41.0 kg = ?? μg

c.) 9.2 mL = ?? μL d.) 9.16 x 10-5 m = ?? nm

9. The distance between two adjacent peaks on a wave is called the wavelength. The wavelength of visible light determines its color.

a.) The wavelength of a beam of green light is 545 nm. What is its wavelength in meters?

b.) The wavelength of a beam of red light is 683 nm. What is its wavelength in inches?

10. A home fashions designer from Europe comes to the United States and decides to purchase some gorgeous fabric that she knows she cannot find back in her home town. She asks the salesperson at the fabric store to cut

36 m2 of the material. The salesperson unfortunately does not have a measuring tape that gives meters, but she has one that measures yards (1 yd = 3 ft). How many square yards does the salesperson need to cut?

11. One manufacturer boasts that their car offers a gas mileage of 32 mi/gal. A European manufacturer advertises that their car has a gas mileage of 15 km/L. Which car would be more economical to operate on the basis of gas mileage? Justify your answer with the appropriate calculation(s). (1 gal = 3.785 L)

12. The volume of a certain bacterial cell is 1.72 μm3.

a.) What is the cell’s volume in cubic millimeters, mm3?

b.) What is the volume in liters of 1.0 x 105 of these bacterial cells?

13. An Olympic-size pool is 50.0 m long and 25.0 m wide.

a.) How many gallons of water (assume dwater = 1.00 g/mL) are needed to fill the pool to an average depth of 4.8 ft?

b.) What is the mass in kg of water in the pool?

14. Nutritional tables give the potassium content of a standard apple (about 3 apples per pound, lb.) as 159 mg. How many grams of potassium are in 4.25 kg of apples? (1 lb = 453.592 g)


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Part 5. Key Concepts of First Unit: Atomic Mass and Mole Number

Average Atomic Mass

A single atom is extremely small. The typical atom will have a mass of approximately 3 x 10-23 g. The smallest mass that the standard analytical balance can weigh reliably is 0.0001 g, which corresponds to roughly 3 quintillion (i.e., 3,000,000,000,000,000,000) atoms. Therefore, we define

1 amu = 1.6606 x 10-24 g

to make it convenient to discuss the mass of very small particles in terms of atomic mass units (amu) rather than very tiny fractions of what can be weighed out on a balance.

An overwhelming majority of the elements that are encountered in the chemistry lab have two or more naturally occurring isotopes. If an element has more than one naturally occurring isotope, then a random sample of the element should be assumed to exist as a mixture of these isotopes that are found in Nature.

Carbon has been found to be 98.89% 12C and 1.11% 13C. Carbon-12 (chosen by the scientific community to define the amu) has an isotopic mass of exactly 12 amu (i.e., one 12C atom weighs 12 amu) and that of 13C is 13.0034 amu.

It is assumed that the composition of a sample of an element (in terms of the percent natural abundances of each of the element’s isotopes) is the same everywhere on Earth. Therefore, in any sample containing carbon (be it a diamond or an organic compound containing carbon in addition to other elements), 98.89% of the carbon atoms in that sample will be C-12 (each weighing 12 amu) and the remaining 1.11% of the carbon atoms will be C-13 (each weighing 13.0034 amu), regardless of where the sample was taken from.

We now determine the average atomic mass of carbon in a manner that is organized and easy to follow (i.e., by tabulating what we know and what we can derive from our given information):

Key Questions (answer all questions on a separate page.)

1. If you were able to select one carbon atom at random, what is the mass of that atom most likely to be (in amu)? Why?

2. Yes or No (Circle your answer.): Does any carbon atom anywhere in the Universe have a mass equivalent to the average atomic mass of carbon on Earth? Briefly explain your reasoning.

3. a. What is the mass in amu of ten sextillion (i.e., 1022) Carbon-12 atoms? Show your work and circle your answer.

b. What is the mass in grams of ten sextillion Carbon-12 atoms? Show your work and circle your answer.

c. What is the mass of ten sextillion Carbon-13 atoms (in g)? Show your work and circle your answer.


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4. If a diamond consisting of ten sextillion “randomly-selected” carbon atoms (roughly a “one-karat diamond”) were placed on an analytical balance, the balance would read (circle your answer and briefly explain your reasoning below):

a.) slightly less than 0.1993 g d.) slightly less than 0.2159 g

b.) 0.1993 g e.) 0.2159 g

c.) slightly more than 0.1993 g f.) slightly more than 0.2159 g

Explanation:

Exercises

5. Europium has two naturally-occurring isotopes. Use the data in the table below to determine the average atomic mass of europium to the nearest 0.1 amu. Hint: Complete the table similarly to what is shown for carbon in the Model.

Isotope Isotopic Mass(amu) Percent Natural Abundance Mass Contribution(amu)

151Eu 150.92 47.8

153Eu 152.92 52.2

Average Mass (amu):

6. 20.5% of germanium is Ge-70, which has an isotopic mass of 69.924 amu. 27.4% of germanium is Ge-72, which has an isotopic mass of 71.922 amu. 7.8% of germanium is Ge-73, which has an isotopic mass of 72.923 amu. 36.5% of germanium is Ge-74, which has an isotopic mass of 73.921 amu. The rest of naturally-occurring germanium is Ge-76, which has an isotopic mass of 75.921 amu. Use this data to calculate the average atomic mass of germanium to the nearest 0.01 amu.

7. Copper has two naturally occurring isotopes, 63Cu (isotopic mass 62.9396 amu) and 65Cu (isotopic mass 64.9278 amu). If copper has an atomic mass of 63.546 amu, what is the percent abundance of each element? Show your work and circle your answer.

Key Questions

8. a. Look at the Periodic Table. How do the numbers under the symbols for carbon, europium, and germanium compare to 12.01 amu and the values you determined in Exercises 5 and 6 respectively?

b. What is the number under the symbol of an element on the Periodic Table?

Exercises

9. a. One often buys donuts by the dozen. How many donuts are there in a dozen donuts?

b. Abraham Lincoln started his Gettysburg Address with the words, “Four score and seven years ago…” How many years are there in a score of years?


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c. Cheap plastic jewelry is very often sold “by the gross”. How many plastic necklaces are there in a gross of necklaces?

d. A mole of liquid water occupies a volume of approximately 18 mL. How many water molecules are in a mole of water molecules?

10. a. 1 mol of items is 6.022 x 1023 of those items. 1 carbon atom weighs on average 12.01 amu. 1 amu is equivalent to 1.6606 x 10-24 g ( or 1 g is equivalent to 6.02x1023 amu) . Use the Factor-Label Method to calculate the mass (in grams) of a randomly chosen sample of carbon containing 1 mole of carbon atoms. Circle your answer.

b. Look at the Periodic Table. How does the number under the symbol for carbon compare to the number of grams you determined in Question 10a?

c. What is the relationship between the units “atomic mass units” and “grams per mole”?

The Mole Concept

Important!! For answers that involve a calculation you must show your work neatly using dimensional analysis with significant figures and units to receive full credit. No work, no credit. CIRCLE ALL NUMERICAL RESPONSES.

1. The atomic mass of Cl is 35.45 amu and that of Al is 26.98 amu. What are the masses in grams of…

Example: 2.0 mol of Al atoms? 2 mol of Al x 6.02x1023 Al atoms x 26.98 amu x 1.6606 x 10-24 g = 53.96 g 1 mol of Al 1 Al atom 1 amu

a.) 3.0 mol of Cl atoms? Circle your answer.

b.) 3.0 mol chlorine molecules? Circle your answer.

2. a.) Why might the expression “1.00 mol of nitrogen” be confusing?

b.) What change would remove any uncertainty?

c.) For what other elements might a similar confusion exist? Why?


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5. Calculate the molar mass of each of the following to two decimal places.

Example: Aluminum oxide: Al2O3: 2Al+3O= 2x26.98+3x16.00=101.96 g/mole

a.) Dinitrogen tetroxide Circle your answer.

b.) Calcium acetate Circle your answer.

6. Calculate each of the following quantities:

Example: The number of moles of chlorine atoms in 0.0425 g of C2H4Cl2.

2C+4H+2Cl=2x12.00+4x1.008+2x35.45 = 98.93 g/mole

0.0425 g of C2H4Cl2 x 1 mole C2H4Cl2 x 2 moles of Cl = 4.30x10-4 mol of Cl 98.93 g 1 mole C2H4Cl2

b.) The total number of ions in 38.1 g calcium fluoride, CaF2. Circle your answer.

c.) Mass in grams of 3.52 mol of chromium (III) sulfate decahydrate. Circle your answer.

d.) Mass in grams of 9.64 x 1024 molecules of dichlorine heptaoxide. Circle your answer.

e.) Number of moles and formula units in 56.2 g of lithium sulfate. Circle your answer.

f.) Number of lithium ions, sulfate ions, S atoms and O atoms in the mass in the previous problem (i.e. in 56.2 g of lithium sulfate) Circle each answer.

7. Calculate the mass % of iodine, I, in strontium periodate. Circle your answer.

8. Oxygen is required for metabolic combustion of foods. Calculate the number of atoms in 38.0 g of oxygen gas, the amount absorbed into the blood from the lungs at rest in 15 minutes. Circle your answer.

9. Propane, C3H8, is widely used in liquid form as a fuel for barbecue grills and camp stoves. For 75.3 g of propane calculate the following:

a.) the moles of the compound in the sample Circle your answer.

b.) the grams of carbon in the sample Circle your answer.

10. The effectiveness of a nitrogen fertilizer is determined mainly by the % N. Calculate the %N in each fertilizer and then rank them in terms of their effectiveness (i.e by their %N).

a. potassium nitrate Circle your answer.

b. ammonium nitrate Circle your answer.

c. ammonium sulfate Circle your answer.

d. urea, CO(NH2)2 Circle your answer.

Practice Quizzes/Tests: Attempt the following quizzes to review, to get a minimum of 90 percent in each quiz. Softschools.com topic-wise quizzes http://www.softschools.com/quizzes/chemistry/

http://www.softschools.com/quizzes/chemistry/

ap chemistry summer packet 2019 - cmit...

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