Grade 7 Unit One Worksheets

Solutions and Mixtures

Work Sheet One

1. In your own words, explain the meaning of each of the following terms:

(a) matter

(b) mass

(d) classify

2. List five substances that you use at home or school that dissolve when mixed with water.

3. Examine the photograph of the various items in the Getting Started section. Sort the items into boxes, drawn in your notebook, based on common characteristics. Identify the properties you used to classify the materials below each box.

4. Design a procedure to investigate the different types of waste generated in a Grade 7 classroom.

(a) What question will you investigate?

(b) Write a hypothesis for your investigation.

(c) Plan a controlled procedure to answer your question and, with your teachers permission, carry out your investigation.

(d) Organize your results in a pie chart and present your findings.

(e) What categories did you use to classify the waste items?

(f) How much of the waste could be reused or recycled?

5. Why are the students shown in Investigation 1.1 wearing gloves and safety goggles? What precautions should you take at home when using hazardous materials?

6. Write a short report explaining what types or categories of materials are discarded in a grade 7 class every day. Then develop a multimedia advertising campaign to try to reduce the amount of waste being generated in the classroom.

Worksheet Two

1. For which of the following mixtures would you be able to use a filter to separate the components?

(a) flour and water

(b) salt water

(d) pop

2. With the aid of a diagram, use the particle theory to explain why a filter is able to separate particles from a mechanical mixture but not from a solution.

3. Suppose you filtered a solution of sugar and water. What test, other than tasting, could be done to show that the sugar particles passed through the filter paper?

4. Would it be more effective to separate particles from water using a series of filters with progressively smaller mesh sizes or to use one filter with small mesh size? In one or two paragraphs, explain reasons for your answers.

5. Compile a list of filters used at home and at school. Organize this information in a table and indicate the purpose of each filter.

6. Would filtering be a viable means or removing particles from large amounts of polluted water? Write a short report describing why or why not. Use diagrams and illustrations if necessary.

Worksheet 3

1. You notice that a flashlight produces a well-defined beam of light on a foggy evening. Does this suggest that fog is a solution or a mechanical mixture? Justify your answer.

2. Fill in the blanks.

A ______________ is a homogeneous mixture of two or more __________ substances. The substance present in the greatest amount is called the _______________ while the substance(s) present in lesser amounts is called the __________.

3. What characteristics in a mixture would you look for before using the following separation techniques?

(a) evaporation

(b) filtration

4. Many different solvents are used at home and school. With adult assistance, examine the labels from a variety of products (do not open the container) and complete the following table.

5. Equal amounts of cooking oil and water are placed in a test tube. Two drops of red food colouring are added to the test tube and the contents are mixed. Predict what the contents will look like immediately after mixing and then again after 24 hours. Use diagrams to help explain your predictions.

6. Recent explorations of Mars are interested in determining if water was present in the planet's history. If it turns out that no water was ever present on Mars, would you expect to find solutions on the planet? Write a short report explaining your answer.

7. What general precautions should you observe when working with solvents?

Worksheet Four

1. 50 mL of water is mixed with 50 mL of alcohol. Would you expect the combined volume of the mixture to be 100 mL? Use a diagram to help explain your answer and discuss the role that particle size plays in the final volume of the mixture.

2. Write a brief essay supporting the thesis that dissolving is a physical process, not a chemical one.

3. As the amount of salt in a salt water solution increases, would you expect the freezing point of the solution to change? Why or why not? Write a short report explaining your answer and suggesting one practical application of this knowledge.

Practice Test

1. In your own words, write a brief paragraph describing the main ideas of particle theory.

2. According to the particle theory, describe the difference between a pure substance and a mixture.

3. Provide the missing information in the chart below.

4. Given two homogeneous clear liquids, without tasting, how could you determine which one was distilled water and which one was a salt-water solution?

5. Would evaporation at room temperature be an effective way of separating and collecting any substance dissolved in water? Write one or two paragraphs explaining your answer.

6. List as many solid, liquid, and gas solutions that you can think of that are used at home or school. For each solution, identify the solute(s) and the solvent.

7. Using electronic and print sources, research the process of maple syrup production. Write a brief explanation of the process incorporating words from this section including pure substance, mixture, solution, solute, solvent, particles, evaporation.