Water: The Universal Solvent of Life
Lesson Description
Video Resource
Water as a solvent | Water, acids, and bases | Biology | Khan Academy
Khan Academy
Key Concepts
- Water's polarity
- Solvent properties of water
- Hydrophilic and hydrophobic interactions
Learning Objectives
- Explain how water's polarity makes it an effective solvent.
- Distinguish between hydrophilic and hydrophobic substances and provide examples.
- Describe the role of water as a solvent in biological systems, such as the cytoplasm of cells.
Educator Instructions
- Introduction (5 mins)
Begin by reviewing the structure of a water molecule and its polarity. Briefly discuss hydrogen bonding and its significance. - Video Viewing (10 mins)
Watch the Khan Academy video 'Water as a solvent' (https://www.youtube.com/watch?v=lCvBp73ZJ-A). Encourage students to take notes on key terms and concepts. - Discussion and Explanation (15 mins)
Discuss the video's content, focusing on how water dissolves ionic compounds like sodium chloride. Explain how the partially negative oxygen and partially positive hydrogen atoms interact with ions. Differentiate between the terms solvent and solute. Introduce hydrophilic and hydrophobic, relating these terms to polarity and charge. - Activity: Hydrophilic vs. Hydrophobic Demonstration (15 mins)
Perform a simple demonstration: Mix oil and water in a container. Observe how they separate due to hydrophobic interactions. Add salt to water and observe that it dissolves. Discuss the differences in molecular properties that lead to these observations. - Wrap-up and Assessment (5 mins)
Review the key concepts and administer a short quiz to assess understanding.
Interactive Exercises
- Molecular Modeling
Use molecular modeling kits or online simulations to build water molecules and illustrate their interactions with sodium and chloride ions. Also, build a hexane molecule and show why it won't dissolve in water.
Discussion Questions
- Why is water called the 'universal solvent'?
- How does water's polarity help in dissolving ionic compounds?
- What are some examples of hydrophobic molecules in the human body?
Skills Developed
- Critical thinking
- Scientific reasoning
- Observation
- Data Interpretation
Multiple Choice Questions
Question 1:
Which property of water makes it a good solvent?
Correct Answer: Polarity
Question 2:
A substance that dissolves in water is called a:
Correct Answer: Solute
Question 3:
Which end of a water molecule is attracted to sodium ions (Na+)?
Correct Answer: Oxygen end (partially negative)
Question 4:
A substance that repels water is described as:
Correct Answer: Hydrophobic
Question 5:
The cytoplasm of a cell is primarily composed of:
Correct Answer: Water
Question 6:
Which type of bond holds sodium and chloride together in NaCl?
Correct Answer: Ionic bond
Question 7:
What is the term for a negatively charged ion?
Correct Answer: Anion
Question 8:
Hexane is an example of a _________ molecule.
Correct Answer: Hydrophobic
Question 9:
Which of the following is an example of a hydrophilic substance?
Correct Answer: Salt
Question 10:
The word root 'hydro' refers to:
Correct Answer: Water
Fill in the Blank Questions
Question 1:
Water's ability to dissolve many substances makes it a good _________.
Correct Answer: solvent
Question 2:
The slightly negative part of a water molecule is located near the _________ atom.
Correct Answer: oxygen
Question 3:
__________ substances, like oil, do not dissolve well in water.
Correct Answer: hydrophobic
Question 4:
The substance that is dissolved in a solvent is called the __________.
Correct Answer: solute
Question 5:
__________ substances, like salt, dissolve easily in water.
Correct Answer: hydrophilic
Question 6:
Sodium chloride (NaCl) dissolves in water because water molecules are attracted to the __________ of sodium and chloride.
Correct Answer: ions
Question 7:
An ion with a negative charge is called an _________.
Correct Answer: anion
Question 8:
The prefix 'phobic' means _________.
Correct Answer: fearing
Question 9:
Gasoline is mostly made up of _________, making it a hydrophobic substance.
Correct Answer: hexane
Question 10:
The fact that the sodium ion here, it's an ion, it has charge. It is able to dissolve in the water very easily, because it is attracted to the partially __________ ends of the water molecule.
Correct Answer: negative
Educational Standards
Teaching Materials
Download ready-to-use materials for this lesson:
User Actions
Related Lesson Plans
-
Unlocking Reaction Rates: An Introduction to Kinetics and CatalysisHigh School · Biology -
Unlocking Energy: An Introduction to Cellular RespirationHigh School · Biology -
Mitosis vs. Meiosis: A Deep Dive into Cell DivisionHigh School · Biology -
Lesson Plan for GcjgWov7mTM (Pending)High School · Biology