Red Ink --> Answers Blue Ink --> Teacher’s Explanation
Test for Purity By checking melting point and boiling point By using chromatography To separate solvent from solution: simple distillation To separate mixture of miscible liquids: fractional distillation To separate mixture of solids by dissolving in a solvent followed by: filtration To separate solute from solution: evaporation and crystallization
1. C (both the burette and pipette can measure up to an accuracy of 0.1 cm 3, both the pipette and burette can measure 25.0 cm 3 ) 2. A (pure substance --> fixed melting pt.) 3. B (pure substance --> fixed boiling pt.) 4. A (Air is a mixture, it contains a mixture of gases)
5. D (Chromatography works because the components in the mixture are soluble in the same solvent. If they do not dissolve, they cannot be separated because the solvent cannot carry them across the chromatogram) 6. D (The mixture must be one soluble solid and one insoluble solid)
7. D (Sodium Nitrate decomposes when heated --> crystallization) 8. D (Condenser --> condense vapour to liquid) 9a) Simple distillation 9b) Evaporation to dryness 9c) Filtration 9d) Chromatography
a)Process 1: Addition of water and stirring Purpose: To quickly dissolve the soluble sodium chloride b)Process 2: Filtration Purpose: To separate the insoluble substances from the sodium chloride solution. c)Process 3: Evaporation Purpose: To remove enough water from the sodium chloride solution to form a saturated solution.
d)Process 4: Crystallization Purpose: To allow sodium chloride crystals to form upon cooling.
1. D (why not A, B or C? because the delivery tube does not extend into the liquid.) 2. A (downward delivery --> gas denser than air) 3. D (yellow is pure because it only contains one spot) 3. D (copper (II) sulfate decompose when heated --> crystallization)
5. A (crystal will form on the glass rod because it has a cool surface and allows crystals to form) 6. B (distillation --> boiling then condensation) 7. D (cold water enters from the bottom of condenser, distillate exits from the outlet tube of condenser) 8. B (Only the liquid can be more than 100 o C because the vapour must be at 100 o C and the distillate will surely be lesser than 100 o C)
9. C (Liquid X becomes darker blue because as water is boiled and vaporized, the solution becomes more concentrated --> Lesser and lesser water in the solution.) 10. B (S is soluble so cannot be filtration, cannot use chromatography because S and water is a solution, use distillation (B) because S and water have different boiling points, (C) cannot separate because the condensed water will fall back into the flask)
11a) chromatography 11b) Chlorophyll and xantophyll have different solubility in ethanol. One solute is more soluble in ethanol than the other, and thus, it moves further up the filter paper.