Suspension or Solution

Tomorrow I have a science test, and in it there are some mixtures, and we have to identify whether they are a solution, a suspension or a colloid. Is there an easy way we can identify this WITHOUT getting the mixtures up and seeing whether they sediment or not?  

Note: They are everyday mixtures, like lattes, freshly squeezed orange juice etc.




If the analyte happens to be in a transparent container, shine light on it, see if the light is scattered ([Tyndall effect](https://en.wikipedia.org/wiki/Tyndall_effect)) -- if so, you have either suspension, or colloidal matter. Instead of a laser pointer, a good pocket light (like the ones with [halogen bulb](https://chem.libretexts.org/Core/Physical_and_Theoretical_Chemistry/Physical_Properties_of_Matter/Solutions_and_Mixtures/Colloid) halogen or LEDs) may be used as light source, too.


[![enter image description here](https://i.stack.imgur.com/GWGqH.png)](https://i.stack.imgur.com/GWGqH.png)


([source](http://chemdemos.uoregon.edu/demos/Tyndall-Effect))


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If the solute particles are very small ($\ce{< 1nm}$), then they form a true solution.


If the solute particles are very large ($\ce{1nm < size < 1000nm}$), then they form a collidal solution.


If the solute particles are very large ($\ce{ > 1000nm}$), then they form a suspension.


The numbers are not exact; they are approximate border ranges. A particle with size $\ce{1100nm}$ can form a colloidal solution. The questions given in your test will give the samples whose size lie in the middle range. Otherwise, it is quite difficult to determine what type of solution they will form; it has to be determined experimentally.


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