A mixture contains sand and ammonium chloride…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A mixture contains sand and ammonium chloride.
- Describe how to separate them, and name the changes of state that are used.
- A sample is heated until no more vapour comes off, and of sand is left in the dish. What percentage of the sample was ammonium chloride?
Need a reminder? The key ideaShow
Sublimation is the change of a solid straight into a gas: camphor, naphthalene, iodine, ammonium chloride and dry ice sublime. The reverse is deposition. Heating a mixture can separate a substance that sublimes from one that does not.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. (a) The method. Put the mixture in a china dish, and cover it with an upside down funnel with cotton wool in its neck. Heat gently. The ammonium chloride sublimes, and the vapour turns back into a solid on the cold funnel (deposition). The sand stays in the dish.
Step 2. (b) The mass that sublimed. .
Step 3. The percentage. .
Answer: (a) Sublimation, then deposition on the funnel. (b) .
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