ZERO-IN

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ANALYZE IT

Instruct students to complete the Analysis Questions in their SDRs then discuss them as a class. Use the suggested responses below to guide students’ answers.

• Why are the pH values of the substances in Trial 1 all in the acidic range? The pH values are all in the acidic range because the substances are all acids which produce H⁺ ions in water solution.

• Why are the pH values of the substances in Trial 2 all in the basic range? The pH values are all in the basic range because the substances are all bases that remove H⁺ ions from the water solution.

• What is the relationship between a low pH and the hydrogen ion (H⁺) concentration? A low pH corresponds to a high H+ ion concentration.

• What is the relationship between a high pH and the hydrogen ion (H⁺) concentration? A high pH corresponds to a low H⁺ ion concentration.

• What would the pH of pure water be? The pH of pure water would be 7.

• Why is the pH of tap water not in the neutral range? Tap water usually has dissolved chemicals that result in a slightly acidic or basic pH.

GET FOCUSED

Instruct students to complete the Focus Questions in their SDRs then discuss them as a class. Use the suggested responses below to guide students’ answers.

• What properties make acids and bases chemically reactive? Acids release H⁺ ions when they are mixed with water and bases remove H⁺ ions when they are mixed with water.

• What is the relationship between the concentration of hydrogen ions (H⁺) in a solution and the chemical reactivity of strong and weak acids? Stronger acids are able to release more H⁺ ions when mixed with water resulting in a higher concentration of H⁺ ions. Weaker acids release fewer H⁺ ions resulting in a lower concentration of H⁺ ions.

• What is the relationship between the concentration of hydrogen ions (H⁺) in a solution and the chemical reactivity of strong and weak bases? Stronger bases are able to remove more H⁺ ions when mixed with water resulting in a lower concentration of H⁺ ions. Weaker bases remove fewer H⁺ ions resulting in a higher concentration of H⁺ ions.