AP®ChemistryCollege BoardExam QuestionsUnit 3: Intermolecular Forces & PropertiesSolutions & Mixtures

Solutions & Mixtures (College Board AP® Chemistry)

Exam Questions

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Solutions & Mixtures

1a1 mark

Answer the following questions about the compounds NH2Cl and NCl3. The Lewis electron-dot diagrams of the two compounds are shown.

q4-june-2022-ap-chemistry

Calculate the number of moles of NH2Cl (molar mass 51.48 g/mol) present in 1.0 L of a solution in which the concentration of NH2Cl is 0.0016 g/L.

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1b2 marks

NH2Cl is highly soluble in water, whereas NCl3 is nearly insoluble. Explain this observation in terms of the types and relative strengths of the intermolecular forces between each of the solutes and water.

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1c1 mark

The value of ∆H°vaporization  for NCl3(l) is 32.9 kJ/mol . Calculate the amount of energy required to vaporize a 15.0 g sample of NCl3(molar mass 120.36 g/mol).

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2a2 marks
AlYNz0Sv_q4-june-2017---ap-chemistry

A student investigates various dyes using paper The student has samples of three pure dyes, labeled A , B , and C , and an unknown sample that contains one of the three dyes. The student prepares the chromatography chambers shown above on the left by putting a drop of each dye at the indicated position on the chromatography paper (a polar material) and standing the paper in a nonpolar solvent. The developed chromatograms are shown above on the right.

Which dye (A, B, or C) is the least polar? Justify your answer in terms of the interactions between the dyes and the solvent or between the dyes and the paper.

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2b2 marks

Which dye is present in the unknown sample? Justify your answer.

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