Question

Predicting Outcomes You have been investigating the nature of suspensions, colloids, and solutions and have collected the following observational data on four unknown samples. From the data, infer whether each sample is a solution, suspension, or colloid. $$ \begin{array}{l|l|l|l|l} \text { Sample } & \text { Color } & \begin{array}{l} \text { Clarity (clear } \\ \text { or cloudy) } \end{array} & \begin{array}{l} \text { Settle } \\ \text { out } \end{array} & \begin{array}{l} \text { Tyndall } \\ \text { effect } \end{array} \\ \hline 1 & \text { green } & \text { clear } & \text { no } & \text { no } \\ \hline 2 & \text { blue } & \text { cloudy } & \text { yes } & \text { no } \\\ \hline 3 & \text { colorless } & \text { clear } & \text { no } & \text { yes } \\ \hline 4 & \text { white } & \text { cloudy } & \text { no } & \text { yes } \end{array} $$ Based on your inferences in Data Table 1 , you decide to conduct one more test of the particles. You filter the samples and then reexamine the filtrate. You obtain the data found in Data Table 2 . Infer the classifications of the filtrate based on the data in Data Table 2 . $$ \begin{array}{|l|l|l|l|l|} \hline \text { Sample } & \text { Color } & \begin{array}{l} \text { Clarity } \\ \text { (clear or } \\ \text { cloudy) } \end{array} & \begin{array}{l} \text { On } \\ \text { filter } \\ \text { paper } \end{array} & \begin{array}{l} \text { Tyndall } \\ \text { effect } \end{array} \\ \hline 1 & \text { green } & \text { clear } & \text { nothing } & \text { no } \\ \hline 2 & \text { blue } & \text { cloudy } & \begin{array}{l} \text { gray } \\ \text { solid } \end{array} & \text { yes } \\ \hline 3 & \text { colorless } & \text { clear } & \text { none } & \text { yes } \\ \hline 4 & \text { colorless } & \text { clear } & \text { white } & \text{ no } \\ \hline \end{array} $$

Short answer

Sample 1 is a solution, Sample 2 is a suspension, Sample 3 is a colloid, Sample 4 is a suspension.

Step-by-step solution

- Understanding the Characteristics

Review the properties of solutions, suspensions, and colloids:- Solutions are clear and do not settle out, nor do they exhibit the Tyndall effect.- Suspensions are cloudy, settle out, and do not show the Tyndall effect.- Colloids are clear or cloudy, do not settle out, and exhibit the Tyndall effect.

- Analyze Sample 1

Sample 1 is green, clear, does not settle out, and does not show the Tyndall effect. This indicates that Sample 1 is a solution.

- Analyze Sample 2

Sample 2 is blue, cloudy, settles out, and does not show the Tyndall effect. This indicates that Sample 2 is a suspension.

- Analyze Sample 3

Sample 3 is colorless, clear, does not settle out, and shows the Tyndall effect. This indicates that Sample 3 is a colloid.

- Analyze Sample 4

Sample 4 is white, cloudy, does not settle out, and shows the Tyndall effect. This indicates that Sample 4 is a colloid.

- Verify with Filtering Data (Sample 1)

Sample 1, when filtered, remains green and clear with no residue on the filter paper and no Tyndall effect. This confirms that Sample 1 is a solution.

- Verify with Filtering Data (Sample 2)

Sample 2, after filtering, becomes cloudy again with gray solid residue on the filter paper and shows the Tyndall effect. This confirms that Sample 2 is a suspension.

- Verify with Filtering Data (Sample 3)

Sample 3, after filtering, remains colorless and clear with no residue on the filter paper and shows the Tyndall effect. This confirms that Sample 3 is a colloid.

- Verify with Filtering Data (Sample 4)

Sample 4, after filtering, becomes clear with white residue on the filter paper and no Tyndall effect. This indicates that Sample 4 is a suspension.

Key concepts

Solutions

When you create a solution, you're mixing two or more substances that become perfectly blended together. Consider ocean water: it’s a mixture of salt and water. In a solution, the particles are so small that they cannot be seen, thus making the solution clear. Solutions never settle, and they won’t scatter light, which means they don't show the Tyndall effect.
Key traits of a solution:

• Clear and transparent
• Particles do not settle out
• Do not exhibit the Tyndall effect
• No residue remains after filtration

Suspensions

Suspensions are mixtures where the particles are large enough that they don’t stay mixed and eventually settle out. If you've ever seen muddy water, you've observed a suspension. This type of mixture appears cloudy and can separate over time. Unlike solutions, suspensions do not exhibit the Tyndall effect because the particles do not stay dispersed to scatter light.
Key traits of a suspension:

• Cloudy appearance
• Particles settle out over time
• No Tyndall effect
• Leaves a residue on filter paper after filtration

Colloids

Colloids are a unique type of mixture where the particles are smaller than those in suspensions but larger than those in solutions. An example is milk. Colloids can appear transparent but will scatter light, displaying the Tyndall effect. Colloids do not settle out over time, so they stay mixed.
Key traits of a colloid:

• May appear clear or cloudy
• Do not settle out
• Exhibit the Tyndall effect
• Leave no residue after filtration

Tyndall Effect

The Tyndall effect is a way to distinguish between different kinds of mixtures. It involves light scattering by particles in a colloid or very fine suspension. For example, you can see a beam of light passing through the dust in a room. This effect can only be seen in colloids because the particles are just the right size to scatter light.
Key points about the Tyndall effect:

• Light scattering by particles in a mixture
• Observed in colloids, not in solutions
• Useful for identifying colloids

Filtration

Filtration is a common method used to separate components in a mixture based on particle size. To filter a mixture, you pass it through a filter paper. If the mixture is a suspension, solid particles will be captured on the filter paper, whereas a solution will pass through without any residue. Colloids pass through the filter paper without leaving residue but can be recognized by their Tyndall effect.
Key points about filtration:

• Used to separate mixtures
• Suspensions leave solid residue
• Solutions pass through clear
• Colloids pass through and can be identified by the Tyndall effect