Bath Bombs
What two substances react in a bath bomb to make fizzing bubbles?
Baking soda (sodium bicarbonate) and citric acid.
What is a scientific model used for?
To explain or represent how something works.
In a CER, what is the claim?
The statement or answer to the question.
Is tearing paper chemical or physical?
Physical change
What does the word hypothesis mean?
An educated guess or prediction that can be tested.
Is the fizzing of a bath bomb a chemical or physical reaction?
Chemical reaction.
What does it mean when scientists revise their models?
They update it based on new evidence or data.
In a CER, what counts as evidence?
Data, observations, or facts that support the claim.
Is burning wood chemical or physical?
Chemical change
What are variables in an experiment?
Factors that can change—independent, dependent, or controlled.
What gas is released when a bath bomb reacts with water?
Carbon dioxide (CO₂)
Give one example of an initial model we created in class.
A diagram showing how bath bombs fizz, or how gases form in a reaction.
Why is reasoning important in a CER?
It connects the evidence to the claim and explains why the evidence supports it.
Name one sign of a chemical reaction.
Gas production, temperature change, color change, or new substance forms.
Give an example of a testable question from the bath bomb experiment.
“Does water temperature affect how fast a bath bomb fizzes?”
Why does warm water make a bath bomb fizz faster than cold water?
Heat gives particles more energy, so the reaction happens faster.
Why is an initial model not always 100% correct?
Because it’s based on limited knowledge and may need adjustments.
If your claim is “The bath bomb caused a chemical reaction,” what is one piece of evidence you could use?
Evidence: It produced bubbles/gas that wasn’t there before.
Ice melts into water. Chemical or physical? Explain.
Physical change, because it’s still H₂O, just a different state.
Why do scientists use data tables and graphs?
To organize, visualize, and interpret data clearly.
If a bath bomb breaks into smaller pieces but does not react, is this a chemical or physical change? Explain.
Physical change, because the substance itself doesn’t change—only its size/shape
Scientists made an initial model about how bath bombs fizz. After experiments, they revised it. What step of the scientific process does this represent?
Analyzing results and refining explanations.
Read this scenario: You mix two liquids, and the mixture gets colder. Write a claim, one piece of evidence, and reasoning.
Claim: Mixing the liquids caused a chemical reaction.
Evidence: The temperature dropped.
Reasoning: A chemical reaction can absorb energy, making the mixture colder.
A bath bomb fizzes and makes bubbles. Explain why this is chemical, not physical.
A new substance (CO₂ gas) is formed, which shows a chemical change.
Why is repeating an experiment important in science?
To check accuracy, reliability, and consistency of results.