Unit / Matter / water
Enduring Understanding / Water with dissolved gases and other chemicals causes the minerals in rocks to be changed, leading to the deterioration of the rock (chemical weathering). Acid rain, produced by pollutants in the air, is a common cause of chemical weathering.
SOL Objectives / 6.5 The student will investigate and understand the unique properties and characteristics of water and its roles in the natural and human-made environment. Key concepts include
a) water as the universal solvent;
b) the properties of water in all three phases;
c) the action of water in physical and chemical weathering;
d) the ability of large bodies of water to store thermal energy and moderate climate;
e) the importance of water for agriculture, power generation, and public health; and
f) the importance of protecting and maintaining water resources.
Title / Does stronger acid cause more chemical weathering?
Lesson Objective / Design an experiment to determine whether the strength of acidified water affects the degree to which chemical weathering happens
Inquiry Level / 3
Materials Needed / · Beakers
· Chalk
· Vinegar
· Water
· Scales
· Rulers
How is it Level 3? / Teacher provides the research question and the materials. The methodology is developed by the students.
Does stronger acid cause
more chemical weathering?
Chemical weathering – the dissolving or breaking down of rocks during a chemical reaction. Often, chemical weathering happens when rocks are exposed to some kind of acid in the environment.
Acid rain – Rain that has been made acidic by certain pollutants in the air.
Test it!
In order to answer this question, design an experiment using some or all of
the materials below.
Materials:
· Acidified water – Strong acid
· Acidified water – Medium acid
· Acidified water – Weak acid
· Regular tap water
· Beakers
· Tongs
· Gypsum sticks (chalk)
· Scale
· Ruler
· Paper towels
· Your brain
Step 1: Discuss your plan with your group members.
You might want to think about the following questions:
- How will you use the strong, medium, and weak acid?
- What will you do the same for all groups to ensure fairness?
- What will you measure about each group for your results?
Step 2: Complete your experimental design on the next page…
Research question: What is the effect of different strengths of acid on how much chemical weathering will occur?
Independent variable
What factor will you change? ______
Dependent variable
What factor will you measure? ______
Hypothesis:
______
______
Sample hypothesis:
If ice cubes are placed in containers made out of glass, plastic, and metal,
then the ice cubes will melt fastest in the metal container.
Experimental groups: 1. ______2. ______3. ______
Control group: ______
Constants (what factors will be kept the same across all groups to ensure fairness?)
1. ______2. ______3. ______
Method:
1.
2.
3.
4.
5.
6.
7.
Results
Group #1______ / Group #2
______ / Group #3
______ / Control
______
Graph
Lab summary
Directions: Please answer the questions below thoughtfully and in complete sentences.
Purpose
What question were you trying to answer by conducting this experiment?
Method
Explain (briefly) the steps that you followed to set up and conduct the experiment.
Results
State the results for each group. Tell which group (if any) had the highest value, and which had the lowest.
Conclusion
Compare the results to your hypothesis and state whether your hypothesis is supported or not.
Explain why you believe you got the results that you did.
Reflect on your methods. What could you do differently to make the results more valid (reliable) next time?