F hydrogen phosphide phosphine gas is added to boron

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Unformatted text preview: d. (e) Zinc metal is placed in a solution of copper(II) sulfate. (f) Hydrogen phosphide (phosphine) gas is added to boron trichloride gas. (g) A solution of nickel(II) bromide is added to a solution of potassium hydroxide. (h) Hexane is combusted in air. © 2006 The College Board. All rights reserved. Visit apcentral.collegeboard.com (for AP professionals) and www.collegeboard.com/apstudents (for students and parents). GO ON TO THE NEXT PAGE. 9 2006 AP® CHEMISTRY FREE-RESPONSE QUESTIONS Your responses to the rest of the questions in this part of the examination will be graded on the basis of the accuracy and relevance of the information cited. Explanations should be clear and well organized. Examples and equations may be included in your responses where appropriate. Specific answers are preferable to broad, diffuse responses. Answer BOTH Question 5 below AND Question 6 printed on pages 11-12. Both of these questions will be graded. The Section II score weighting for these questions is 30 percent (15 percent each). 5. Three pure, solid compounds labeled X , Y , and Z are placed on a lab bench with the objective of identifying each one. It is known that the compounds (listed in random order) are KCl , Na2CO3 , and MgSO4 . A student performs several tests on the compounds; the results are summarized in the table below. Compound pH of an Aqueous Solution of the Compound Result of Adding 1.0 M NaOH to a Solution of the Compound Result of Adding 1.0 M HCl Dropwise to the Solid Compound X >7 No observed reaction Evolution of a gas Y 7 No observed reaction No observed reaction Z 7 Formation of a white precipitate No observed reaction (a) Identify each compound based on the observations recorded in the table. Compound X ______________________ Compound Y ______________________ Compound Z ______________________ (b) Write the chemical formula for the precipitate produced when 1.0 M NaOH is added to a solution of compound Z . (c) Explain why an aqueous solution of compound X has a pH value greater tha...
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This note was uploaded on 10/01/2009 for the course OC 9876 taught by Professor Dq during the Spring '09 term at UC Merced.

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