In this lab, students devise their own method to separate a mixture of sand, salt, poppy seeds, and iron filings.
High or middle school
By the end of this lesson, students should be able to
- identify physical properties of each of the four substances.
- identify appropriate methods for separating mixtures.
This lesson supports students’ understanding of
- Separating mixtures
Teacher Preparation: 1 hour
Lesson: two 55-minute periods
For each group:
- Always wear safety goggles when working with chemicals in a laboratory setting.
- Use caution and wear protective equipment when working with hot objects.
- The mixture should contain approximately equal amounts of each of the four substances.
- Be sure to measure the exact amount of each substance included in each group’s mixture so that you know which group was closest to 100% separation.
- Encourage students to experiment with the test mixture and the individual components before attempting to separate their actual mixture
For the Student
Separation and recovery of pure substances are extremely important operations of scientific research and industry, but separating the different components in a mixture can often prove quite challenging. In this investigation, you will have an opportunity to design, develop, and implement your own (with a partner) procedure in an attempt to separate and recover the components of a mixture. The mixture contains the following four substances in dry granular forms: salt, sand, iron filings, and poppy seeds.
The team that gets closest to a 100% recovery of each component will win a prize.
It’s all in your hands. Brainstorm with your partner how you will separate the mixture. Consider the materials available to you. What do you need to know about each of the components before you decide how to separate them? How can you find these things out? If you need to do any preliminary testing, do it before beginning the actual separation.
Before you can begin, you will need a preliminary procedure. You can write it in step-by-step form, in a flow chart form, or using pictures. While you actually perform the separation, you will need to document exactly what you do. This will be more detailed than your initial procedure and in a step-by-step format.
You will need to determine the final masses of the products you collect so your teacher can determine how close to 100% recovery you are.
- How successful were you (on a scale of 1-10) in separating and recovering each of the four components? Justify your success based on your observations/data.
- For each of the four components, describe the specific physical property that enabled you to separate it from the rest of the mixture.
- What made you decide to do your procedure steps in the order in which you did them? Would any order have worked? Explain.
- If you could do the lab over again, what specific things would you do differently? Explain.
- What two materials or tools that weren’t available may have made your separation easier?