HardChemistryHigh School (9–10)GeneralMixtures and Solutions › Elements, Compounds and ChangesNumericalBoard Exam
Iron and sulphur join to make iron sulphide in the ratio 7 : 4 by mass…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Iron and sulphur join to make iron sulphide in the ratio by mass. A student heats of iron with of sulphur. How much iron sulphide forms, and how much of which element is left over?
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. Sulphur needed. of sulphur. There is , so the iron is used up first.
Step 2. Iron sulphide. .
Step 3. Left over. of sulphur.
Answer: of iron sulphide, with of sulphur left over.
Check. , the same as : no mass is lost.
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