Solutions and Pollution Pacing Guide (23 instructional days)

Lesson / Recommended Number of Periods / Focus Questions / Concepts
Investigation 1:
Investigating Mixtures / 2 /
  • What does it mean when a substance dissolves?
  • How can dissolved and undissolved substances be separated?
  • Why is it important to have only one variable in an investigation?
/
  • Clean water is essential for life on earth.
  • Some substances dissolve in water, others do not.
  • All matter is particulate in nature.
  • Filters can remove undissolved solid particles from a liquid.
  • A well-designed investigation tests only one variable.

Investigation 2:
Investigating Solutions / 1 /
  • What are the possible solutions that result from mixing solids in varying amounts in a liquid?
/
  • A solution exists when one substance, the solute, dissolves in another, the solvent.
  • Solubility, the amount of a substance that can dissolve, varies from substance to substance.
  • A solution into which no more of a substance can be dissolved is a saturated solution.
  • Dissolved particles may or may not be detectable by sight; undissolved particles are visible.

Investigation 3:
Reproducibility and Proper Use of Laboratory Equipment / 1 /
  • What is necessary for results from investigations to be reproducible?
/
  • A well-designed investigation tests only one variable.
  • Standardizing laboratory techniques is essential for obtaining reproducible results.

Investigation 4:
Comparing Solubility / 3 /
  • Do solids dissolve the same way in different liquids?
  • What is the difference between clear and colorless?
/
  • Water can dissolve many different solutes and is often called the universal solvent.
  • Water’s ability to dissolve many substances is both helpful and harmful to living organisms.

Investigation 5:
Parts Per Million / 3 /
  • What is the difference between “observations” and “inferences”?
  • What is the difference between qualitative and quantitative observations?
  • What is meant by “ppm”?
/
  • The concentration of a dissolved substance can be expressed in several different ways, including parts per million (ppm) and parts per billion (ppb).
  • Adding water to a solution dilutes the concentration of any dissolved substances and can change the properties of the solution.

Investigation 6:
Identifying Acid and Base Solutions / 2 /
  • What are acids, bases and indicators?
  • How can an acid or base be made to change to the other?
  • Is the ACME wastewater an acid or a base?
  • What is one piece of evidence that a chemical change has occurred when an indicator is mixed with an acid or a base?
/
  • All solutions can be classified as either acidic, basic, or neutral.
  • Acidic, basic, and neutral solutions have different chemical properties that can be used to differentiate them.
  • Chemicals that change color in the presence of certain chemicals are called chemical indicators.

Investigation 7:
Diluting Acids and Bases / 2 /
  • What happens to acids and bases as more water is added to each?
/
  • Adding water to a solution dilutes the concentration of any dissolved substances and can change the properties of the solution.
  • As the concentration of an acidic or basic solution lowers, the properties of the solution become increasingly similar to those of water.
  • The pH scale classifies the relative acidity or basicity of a solution.
  • A solution’s pH affects the way that solution will react with other substances and with living organisms.

Investigation 8:
Acid-Base Neutralization / 4 /
  • How can an acid or a base be made to be more like water? (What is meant by neutralization?)
  • What can be inferred when different amounts of a base are required to neutralize an acid with an equal percent concentration?
/
  • Combining an acid with a base produces a chemical reaction that results in a solution with an intermediate pH.
  • If combined in a specific ratio, any acid and base can combine to produce a neutral solution.
  • Acids and bases neutralize each other on a one-to-one particle basis.
  • Neutralization reactions can be used to treat non-neutral wastewater.

Investigation 9:
Removing Dissolved Substances from a Solution / 2 /
  • What can happen when two solutions are mixed?
  • What is the evidence a chemical change has occurred?
/
  • Chemical reactions often cause easily observable changes.
  • When a chemical reaction produces an insoluble product, the product appears as a precipitate.
  • Filters can remove undissolved solid particles from a liquid.
  • Chemical reactions can be described by chemical equations.
  • Chemicals react with each other on a one-to-one particle basis.
  • Precipitation reactions can be used to treat wastewater containing dissolved substances.

Investigation 10:
Treating ACME Wastewater / 3 /
  • Considering dilution, filtration, neutralization and precipitation, what is the best procedure (or set of procedures) for making the ACME wastewater more like fresh water in order to safely dispose of it into BarksdaleLake?
/
  • A technological solution to a problem can be tested and revised through experimentation.
  • Perfectly designed solutions do not exist; all solutions have trade-offs.