Name ______Per. _____

Separating Substances in a Mixture

Objectives:

  1. Identify physical properties that can be used to extract different substances from a mixture.
  2. Develop methods for extracting substances from a mixture.
  3. Evaluate the effectiveness of your methods, and recommend improvements.

Day #1 – Observing & Thinking

  1. Observe the physical properties of each of the following substances: cracked pepper, iron filings, peanuts, sand, sugar, and water. Do not taste or eat any of these substances.
  2. For each substance, indicate which physical properties it has and record below:

Physical Properties of Individual Substances

Substance / Soluble in Water? / Does it float? / Is it magnetic? / Relative size? / Solid, liquid, Gas?
Cracked Pepper
Iron Filings
Peanuts
Sand
Sugar
Water
  1. Now, determine which method you will use to separate each substance from the mixture you will receive. Remember, you want to extract as much of the substance as possible. Your grade is partly based on the mass of each substance you separated.

Best Method for Substance Separation

Substance / Procedures for Separation
Cracked Pepper
Iron Filings
Peanuts
Sand
Sugar
Water

Day #2 – Separating Your Mixture

  1. Follow your plans to separate each substance from the mixture. As you extract the substances from the mixture, store each substance in a different cup, and label each cup. Measure the cup empty and again with the substance. Subtract the difference to obtain the mass of each individual substance and record below:
  2. After receiving actual masses from your teacher, calculate the percent error for each substance and record below.

Masses and % Errors of Substances Extracted

Substance / Mass of Empty Cup / Mass of Cup & Substance / Mass of Substance / Actual Mass given by teacher / % Error =
Measured – Actual*100
Actual
Cracked Pepper
Iron Filings
Peanuts
Sand
Sugar
Water

Analysis – Use the back of this paper if you need more room to answer.

  1. List the substances in the mixture in order from the least mass extracted to the greatest mass extracted.
  1. Was this mixture a homogeneous mixture or a heterogeneous mixture? ______
  1. What it a suspension, a colloid, an emulsion, or a solution? ______
  1. What problems did you encounter during the process of separating the mixture?
  1. How could you improve your methods to better separate each substance?
  1. A centrifuge is a device that uses centrifugal force to separate substances of different masses. They are often used by biologists and biochemists to separate parts of cells or biological molecules of different masses. How do they work? Use a dictionary, the Internet, or other sources to learn the answer.