Ch. 3 & 11 stochiometry & IMF                      test       70 points                                                                      ap chemistry

Show your work in an organized manner, include (i) any relevant equation (or formula), (ii) conversion factor(s), (iii) put the proper units in your calculations and answer, and (iv) have the proper number of significant figures in your answer.

Academic Honesty:   The answers on this test are my own and I am using only the allowed set of notes as described in the syllabus.  I have not discussed the test questions with anyone before or during the test nor have I seen the test questions prior to the exam.  If you violate any of the preceding items or do not sign, your semester grade is a F.

                                                                                                Signature:  ___________________

1. A 5.0 gram mixture of sodium carbonate and sodium bicarbonate was heated to selectively decompose the sodium bicarbonate in the mixture to form solid sodium carbonate, water vapor, and gaseous carbon dioxide.  After heating, the mixture’s mass was 4.0 grams.  Based on the preceding information, determine the % sodium bicarbonate in the original mixture.  [20 points; hint:  it’s a weekly quiz problem]

2.  In your chromatography lab, using a reverse phase chromatography column, the red and blue dyes were separated from each other using the appropriate concentration of isopropyl alcohol, where the red dye was eluted before the blue dye.  Using concepts of IMF and explicitly referring to chemicals in the system, rationalize the order of elution of these dyes.  [10 points]

3.  In regards to the reaction:  3.0 g Na3PO4  +  6.0 g Ca(NO3)2  à  Ca3(PO4)2  +  NaNO3, the yield = 85 %.  What is the experimental yield of Ca3(PO4)2  in the reaction ?  [20 points]

4, In regards to HI, HBr, and HCl,  [20 points]

a. clearly identify the IMF in each compound

b. What is the relative strength of each IMF component in each compound ?  justify your response.

c. Based on the following boiling points

HI        - 35 ºC
HBr      - 66 ºC
HCl      - 85 ºC

what is the relative strength of the total IMF of each compound ?  justify your response.

d, Based on your response to parts b and c, sketch / label a bar graph summarizing your response.