Product 12761

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Classifying matter into mixtures or pure substances hinges on a key question—how is the composition affected by a physical or chemical change? In this experiment, students use both physical and chemical changes to separate a mixture of iron oxide and salicylic acid. A sample of the mixture is weighed and added to sodium hydroxide solution. After the salicylic acid dissolves, the solution is filtered to isolate the insoluble iron oxide. Hydrochloric acid is then added to the solution to precipitate the remaining salicylic acid, and the solution is filtered again to separate out the salicylic acid. Students dry and weigh each component to determine its mass percent of the mixture. A great quantitative activity for developing student lab skills in filtration and other basic laboratory techniques.

Complete for 30 students working in pairs.