EasyChemistryHigh School (11–12)Atoms and Molecules › Measurement, Units and Significant FiguresMixtures and Solutions › Elements, Compounds and ChangesConceptual
Shreya sorts six things from her kitchen: table salt, a steel spoon, oxygen in a small cylinder…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Shreya sorts six things from her kitchen: table salt, a steel spoon, oxygen in a small cylinder, muddy water from the garden, filtered tea, and distilled water. Put each one in its class: element, compound, homogeneous mixture or heterogeneous mixture. Give a reason for each.
Need a reminder? The key ideaShow
A pure substance has a fixed composition: an element has one kind of atom, and a compound has elements joined in a fixed ratio by mass. A mixture has two or more substances in any ratio. A homogeneous mixture is the same all through; a heterogeneous one is 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. The pure substances. Oxygen has only one kind of atom, so it is an element. Table salt (sodium chloride) and distilled water (hydrogen and oxygen) have elements in a fixed ratio, so they are compounds.
Step 2. The mixtures. Steel and filtered tea are the same all through, so they are homogeneous mixtures. Muddy water has particles you can see and that settle, so it is a heterogeneous mixture.
Answer: element: oxygen; compounds: table salt and distilled water; homogeneous mixtures: the steel spoon and filtered tea; heterogeneous mixture: muddy water.
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