HardChemistryHigh School (9–10)GeneralMixtures and Solutions › Elements, Compounds and ChangesNumericalConceptualBoard Exam
Three samples of a white solid are analysed…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Three samples of a white solid are analysed. Sample 1 has of element A and of element B. Sample 2 has of A and of B. Sample 3 has of A and of B. Which samples could be the same compound? Why?
Need a reminder? The key ideaShow
A compound is two or more elements joined chemically in a fixed ratio by mass, with new properties, split only by a chemical change. Water is hydrogen and oxygen in the ratio ; iron sulphide is iron and sulphur in the ratio . A mixture can have any ratio.
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. Sample 1. .
Step 2. Sample 2. .
Step 3. Sample 3. .
Answer: Samples 1 and 2 have the same fixed ratio, so they could be the same compound. Sample 3 has a different ratio: it is a different substance, or a mixture.
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