Chapter 5 Test: Mixtures...And How To Separate Them
Questions and Answers
- 1.
Be as specific as possible and answer in complete sentences.
- 2.
For questions 10-12: A thousand gallons of petroleum (crude oil) are removed from the ground and fractionally distilled. The boiling points of some of the substances in petroleum are listed in the table below. A graph of the temperature of the vapor above the liquid as a function of time appears below the table. Substance Boiling Point (C) 1 70 2 98 3 125 4 151 Which substance or substances will be collected during time interval IV?
- 3.
For questions 10-12: A thousand gallons of petroleum (crude oil) are removed from the ground and fractionally distilled. The boiling points of some of the substances in petroleum are listed in the table below. A graph of the temperature of the vapor above the liquid as a function of time appears below the table. Substance Boiling Point (C) 1 70 2 98 3 125 4 151 Which substance or substances will still be present in the original liquid mixture at the beginning of time interval II?
- 4.
For questions 10-12: A thousand gallons of petroleum (crude oil) are removed from the ground and fractionally distilled. The boiling points of some of the substances in petroleum are listed in the table below. A graph of the temperature of the vapor above the liquid as a function of time appears below the table. Substance Boiling Point (C) 1 70 2 98 3 125 4 151 During which time intervals would the substance collected definitely be a pure substance?
- 5.
Suppose you try to separate a mixture of two solid substances by stirring the mixture with water, filtering, and evaporating the filtrate. You do this and find nothing on the filter paper. a. Explain why this procedure failed to separate the mixture, referring to a specific characteristic property. b. What could you try next to separate the mixture?
- 6.
By paper chromatography, you separate the solid dyes in black ink into three substances (blue, red, yellow). You dissolve each substance in water, mix the solutions, and obtain a clear, purple solution. Why is the solution lighter than the original ink?
- 7.
This whole chapter has been about separating mixtures. In a few sentences, explain as best you can why this is an idea worth understanding. Use real world examples that we have discussed in class. Think this through--answers like 'just because' or 'because we have to'--won't earn much credit here!
- 8.
1. Read all questions carefully and try to eliminate choices that are obviously wrong. 2. If stuck on a question, skip it for now and come back later (don't forget to come back to it eventually) 3. In essays, think before you write and be sure to answer the question that is asked. 4. Please ask for clarification if something is unclear to you. 5. Take your time and do your best. You will never regret doing the best you can.
- 9.
Characteristic properties of substances are useful for all of the following reasons except:
- A.
They can help separate mixtures.
- B.
They can help identify pure substances.
- C.
They can tell you how much of the substance you have.
Correct Answer
C. They can tell you how much of the substance you have.Explanation
Characteristic properties of substances, such as boiling point, density, and solubility, are useful for separating mixtures and identifying pure substances. These properties can be used to determine the composition of a mixture and distinguish between different substances. However, they do not provide information about the quantity or amount of the substance present. To determine the amount of a substance, other techniques such as measuring mass or volume are required. Therefore, the statement that characteristic properties can tell you how much of the substance you have is incorrect.Rate this question:
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- 10.
Which of the following is a pure substance and NOT a mixture?
- A.
The dirt under your feet
- B.
The blood in your veins
- C.
The seawater in the Atlantic Ocean
- D.
The isopropanol in rubbing alcohol
Correct Answer
D. The isopropanol in rubbing alcoholExplanation
The isopropanol in rubbing alcohol is a pure substance and not a mixture because it consists of only one type of molecule. It is a homogeneous substance with uniform properties throughout. In contrast, the dirt under your feet, the blood in your veins, and the seawater in the Atlantic Ocean are all mixtures that contain multiple types of substances.Rate this question:
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- 11.
Which of the following can NOT be used to separate mixtures?
- A.
Solubility
- B.
Volume
- C.
Melting point
- D.
Boiling point
- E.
Density
Correct Answer
B. VolumeExplanation
Volume cannot be used to separate mixtures because it is a measure of the amount of space occupied by a substance, not a property that can be used to differentiate or isolate different components of a mixture. Separation of mixtures is typically achieved using properties such as solubility, melting point, boiling point, and density, which can be used to selectively separate the components based on their different physical or chemical characteristics.Rate this question:
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- 12.
Which characteristic property allowed us to separate the pigments found in ink?
- A.
Melting point
- B.
Density
- C.
Boiling point
- D.
Solubility
- E.
Freezing point
- F.
Flammability
Correct Answer
D. SolubilityExplanation
Solubility is the characteristic property that allowed us to separate the pigments found in ink. This is because solubility refers to the ability of a substance to dissolve in a solvent. By using different solvents with varying solubilities, we can effectively separate the pigments based on their solubility properties.Rate this question:
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- 13.
Which characteristic property let us separate a mixture of isopropanol and water?
- A.
Melting point
- B.
Density
- C.
Boiling point
- D.
Freezing point
- E.
Solubility
Correct Answer
C. Boiling pointExplanation
The boiling point is the characteristic property that allows us to separate a mixture of isopropanol and water. Isopropanol and water have different boiling points, with isopropanol having a lower boiling point than water. By heating the mixture, the isopropanol will evaporate first, leaving behind the water. This process is known as distillation and is commonly used to separate mixtures of liquids with different boiling points.Rate this question:
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- 14.
You have a pile of sawdust with tiny bits of nails mixed in it. You want to compost the sawdust, but obviously not the metal bits. Which characteristic property could you take advantage of to separate the metal from the sawdust in this mixture?
- A.
Melting point
- B.
Freezing point
- C.
Boiling point
- D.
Density
- E.
Solubility
Correct Answer
D. DensityExplanation
Density is the characteristic property that could be taken advantage of to separate the metal from the sawdust in this mixture. Density is the measure of how much mass is contained in a given volume. Since metal is denser than sawdust, it will sink to the bottom when the mixture is placed in water. Sawdust, being less dense, will float on top. This allows for the separation of the metal bits from the sawdust by simply skimming off the floating sawdust or collecting the sinking metal bits.Rate this question:
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- 15.
Potassium nitrate and sodium chloride are both white, crystallized solids at room temperature. Their melting points are too high for our burners to melt them, and the crystals are tiny and impossible to pick out by hand. They have similar solubilities in water at room temperature as well, close to 40g/cm--and their densities are quite similar as well. With all of this said, how could you actually separate these two substances from each other?
- A.
Freeze them
- B.
Dissolve them both in hot water and filter it; repeat to get them more purely separated
- C.
Put them in water and see which one dissolves first
- D.
Put them in water and see which one floats; skim it off the top
Correct Answer
B. Dissolve them both in hot water and filter it; repeat to get them more purely separatedExplanation
To separate potassium nitrate and sodium chloride, both substances can be dissolved in hot water. Since they have similar solubilities, they will dissolve to some extent. However, upon cooling, the solubility of potassium nitrate decreases more than that of sodium chloride. This allows for the separation of the two substances by filtration. By repeating this process, the substances can be separated more purely.Rate this question:
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- 16.
Isopropanol is flammable, doesn't dissolve sugar, and has a density of 0.80g/cm. Water, of course, does not burn, does dissolve sugar, and has a density of 1.00g/cm. If you mixed 100mL of water and 10mL of isopropanol together, which of the following statements would you expect to be false?
- A.
The mixture might burn a little bit.
- B.
The mixture would probably dissolve sugar fairly well.
- C.
The total volume of the mixture would be about 110mL.
- D.
The density of the mixture would be 0.90g/cm^3.
- E.
If given time, the isopropanol would float to the top of the mixture.
Correct Answer
E. If given time, the isopropanol would float to the top of the mixture.Explanation
If given time, the isopropanol would float to the top of the mixture because isopropanol has a lower density than water.Rate this question:
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- 17.
The following substances are all acquired from crude oil. If we were trying to separate a mixture of these by freezing them, which would turn into a solid first? Substance Melting Point (C) Boiling Point (C) Ethane -183 -88 Pentane -129 36 Hexane -94 69 Decane -30 174
- A.
Ethane
- B.
Pentane
- C.
Hexane
- D.
Decane
Correct Answer
D. DecaneExplanation
The substance with the highest melting point would turn into a solid first when the mixture is frozen. In this case, Decane has the highest melting point of -30°C compared to the other substances. Ethane has a melting point of -183°C, Pentane has a melting point of -129°C, and Hexane has a melting point of -94°C. Therefore, Decane would solidify first when the mixture is frozen.Rate this question:
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Mar 21, 2023Quiz Edited by
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Jan 29, 2014Quiz Created by
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