Lesson: Water Chemistry

Why is water so important for life?

This lesson approaches water from a biological standpoint. It relates the chemical structure of water to its myriad of unique properties. Students learn about its heat capacity, the importance of its polarity, its action as a solvent, its role in acid/base reactions and its role in the construction and destruction of polymers.

BIO.2 The student will investigate and understand the chemical and biochemical principles essential for life. Key concepts include

a) water chemistry and its impact on life processes;

• explain the importance of the chemical and physical properties of water that make it vital to life.

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Vocabulary

Water

  • absorb

  • evaporate

  • float

  • polarity

  • cohesive

  • adhesive

  • solution

pH

  • acidic

  • neutral

  • basic

  • buffer

Warm Ups

Acids & Bases - review the principles of acids and bases. This is most effective if done after the pH lab activity. #content #criticalthinking

Hydrogen 2, Oxygen 1 - review the chemical structure and properties of water #content #criticalthinking

Mono-poly - provide instruction on the formation of polymers by dehydration synthesis and the breakdown into monomers by hydrolysis.#content

Content & Presentations

Notes

  • Water - Lecture notes that describe the critical physical and chemical properties of water that make it essential for life.

Presentations

Diagrams - Water (needs revisions!)

- covalent bonding, polarity, neutrality

- acids and bases

- cohesion/adhesion

- heat absorption

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Independent Assignments & Activities

Lab & Group Activities

1. Water Activities - Properties of water

Obj: Demonstrate properties of water to enhance instruction, review scientific methods

Materials: water, cup/plate, salt, beaker, hot plate, ice cubes, sharp probe, probeware (temp/conductivity/pH), graduated cylinders, triple beam balance

Methods: fill cup with water, place plate over it and invert (plate should remain suspended) - discuss adhesion and cohesion - break vacuum with probe

Beakers with equal amount of water and allow them to come to room temp. Weigh ice cubes, pour equal amount of hot water in graduated cylinder. Add ice to one beaker, hot water to the other - record changes

Measure conductivity of water, add salt and observe patterns of change


2. pH Lab - Qualitative (to Quantitative Analysis) - Lab Sheet, Data Analysis Survey

Obj: Perform qualitative analysis of unknown substances using red, blue and yellow litmus papers to obtain quantitative results.

Define variables, constants and controls

Materials: unknowns, litmus papers, forceps, "trash cans", safety goggles, pH probe/probeware

Methods: dip each litmus papers into the liquid (do not allow forceps to touch), record results in chart

Analysis: discuss results, estimate pH, reveal unknowns, discuss bias/errors

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