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Name ________________________
AP Chemistry By Satellite
John I. Gelder
Exam I
September 17, 1991

INSTRUCTIONS:

1. This examination consists of a total of 7 different pages. The last page includes a periodic table and some useful information. All work should be done in this booklet.

2. PRINT your name, high school and teaching partner's name now in the space at the top of this sheet. DO NOT SEPARATE THESE PAGES.

3. Answer all questions that you can and whenever called for show your work clearly. Your method of solving problems should pattern the approach used in lecture. You do not have to show your work for the multiple choice or short answer questions.

4. No credit will be awarded if your work is not shown in problems 5 and 6.

5. Point values are shown next to the problem number.

6. Budget your time for each of the questions. Some problems may have a low point value yet be very challenging. If you do not recognize the solution to a question quickly, skip it, and return to the question after completing the easier problems.

7. Look through the exam before beginning; plan your work; then begin.


8. Relax and do well.


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APCBS Exam I KEY PAGE 2


(8) 1. Write the chemical formula(s) of the product(s) and balance the following reactions which were demonstrated in lecture. Identify all products phases as either (g)as, (l)iquid, (s)olid or (aq)ueous.

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(4) 2. List at least two physical properties for each of the following substances.


a) Br2

volatile, reddish-brown liquid


b) N2

colorless, odorless, tasteless gas


(14) 3. Complete the following table

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APCBS Exam I KEY PAGE 3


(6) 4. Complete the following table;

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(18) 5. The solid fuel used in the space shuttle booster rocket is a mixture of aluminum powder and a perchlorate compound. When the mixture is ignited the reaction is thought to be,

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a) If 54.0 g of aluminum are combined with excess NH4ClO4, calculate the mass of nitrogen produced.

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b) Calculate the mass of water produced when a mixture containing 100. g of aluminum and 100. g of NH4ClO4 are ignited.

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APCBS Exam I KEY PAGE 4

(10) 6. A 0.100 g sample of mesitylene, a hydrocarbon, was burned in excess oxygen to give 0.330 g of CO2. Determine the empirical formula of mesitylene.

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(6) 7. Samples of two different brands of black ink were separated into their component parts using paper chromatography. Both samples contained a red dye. In the first sample the solvent traveled 7.56 cm while the red dye traveled 4.69 cm. In the second sample the red dye traveled 3.32 inches while the solvent traveled 5.36 inches. Is it possible that the same red dye was used to make both types of ink? Justify your answer with calculation(s) and one or two sentences.

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The Rf values for the red dye are same for each sample showing that the dyes have the same attraction for the stationary and mobile phases. This is a good indication that the two inks contain the same red dye. Note: The unit used to measure the distance traveled is not important, as long as the distance traveled by the solute and solvent is measured in the same unit. Rf is a unitless value.


APCBS Exam I KEY PAGE 5


Short Answers:


(3) 8. How many electrons, protons and neutrons are in the isotope BELOW?


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(4) 9. Given that Neptunium-233 undergoes alpha decay, complete the equation which describes the nuclear decay process.

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(3) 10. What is a beta particle and how is it formed in a nuclear decay process?

A beta particle is equivalent to an electron. It is produced when a neutron, in the nucleus of an atom, decays into a beta particle and a proton.

(3) 11. Report the result of the following calculation to the correct number of significant figures.

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(depending on when students round numbers)

(3) 12. Which temperature is higher, -25 ºF or -10 ºC?

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(3) 13. How many significant figures in each of the following numbers?

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(3) 14. Perform one of the following conversions

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APCBS Exam I KEY PAGE 6


Multiple Choice:

Print the letter (A, B, C, D, E) which corresponds to the answer selected.

15. B 16. A 17. E 18. D

ONLY THE ANSWERS IN THE AREA ABOVE WILL BE GRADED. Select the most correct answer for each question. Each question is worth 3 points.

15. Determine the empirical formula of a compound containing 23.1% Al, 15.4% C and 61.5% O by weight.


A) AlCO4
B) Al2C3O9
C) Al3C2O8
D) Al4C5O16


Use diagrams A - E to answer questions 16 and 17.

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16. A solution of carbon monoxide and oxygen at 25 ºC.

A) A
B) B
C) C
D) D
E) E

17. A heterogeneous mixture of two liquids.

A) A
B) B
C) C
D) D
E) E

18. When filtering a mixture of a liquid and a solid, you should

A) swirl the mixture to suspend the solid in the liquid, then quickly pour the mixture into the filter.
B) Decant the liquid into the filter leaving as much as possible of the solid in the container, allowing any remaining liquid to evaporate.
C) Scrape the solid into the filter and then pour the liquid over it.
D) Decant most of the liquid into the filter and then scrape the solid into the filter, using as little liquid as possible to ensure complete transfer.



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