Bath Bomb Breakdown
What happens when a bath bomb is placed in water?
It fizzes/bubbles and eventually breaks apart or dissolves.
Which is an observation: "The water bubbled" or "A chemical reaction happened"?
The water bubbled.
What is a property?
A characteristic of a substance that can be observed or measured.
Ice melting is what type of change?
Physical change.
You make a bowl of cereal with milk. You can see the cereal and the milk separately. Is this homogeneous or heterogeneous?
Heterogeneous -you can see the different parts.
Name 2 observations you could make when a bath bomb is added to water.
Bubbles/fizzing, temperature change, color change, bath bomb getting smaller, etc.
What is the difference between an observation and an explanation?
An observation describes what we detect or measure; an explanation tells why we think it happened.
Name two properties scientists can use to describe a substance.
Examples include color, state, solubility, density, melting point, odor, etc.
Cutting a bath bomb into smaller pieces is what type of change?
Physical change.
You completely stir sugar into lemonade until you cannot see the sugar anymore. Is the mixture homogeneous or heterogeneous?
Homogeneous - the mixture is evenly mixed throughout.
Why did we investigate the ingredients of the bath bomb separately?
To determine which ingredients/properties might help explain what happens when the bath bomb is added to water.
Which is quantitative data: "It fizzed a lot" or "The mass was 108.3 g"?
The mass was 108.3 g.
What does solubility describe?
How well a substance dissolves in another substance.
Two substances interact and a gas forms that wasn't present before. What type of change could this indicate?
A chemical change/reaction.
You have a bag of trail mix containing pretzels, raisins, chocolate pieces, and peanuts. Explain why this is a heterogeneous mixture.
The different substances are not evenly mixed, and you can identify the different parts.
If crushing a dry bath bomb does NOT produce bubbles, what does that suggest about the gas we observe in water?
The gas was probably not simply trapped inside the bath bomb.
Why is measuring mass stronger evidence than saying something "felt heavier"?
Mass is a measurable numerical value that can be compared.
Two white powders look exactly the same. Does that prove they are the same substance?
No. Scientists need to compare additional properties.
Why is dissolving by itself not enough evidence to prove that a chemical reaction occurred?
A substance can dissolve without forming a new substance.
Two cups look different: Cup A: Salt is completely dissolved in water. Cup B: Sand is mixed into water and settles at the bottom. Which is homogeneous and which is heterogeneous?
Cup A is homogeneous because the salt is evenly distributed. Cup B is heterogeneous because the sand is not evenly distributed and can be seen separately.
"The bubbles were just air trapped inside the bath bomb." What evidence from our investigations could challenge this claim?
Crushing/breaking the bath bomb did not release the same gas/bubbling; the bubbling occurred when the ingredients interacted with water.
Two students disagree about what happened during an investigation. What should they use to decide which explanation is better supported?
Evidence/data from their investigation.
Substance A and Substance B are both white powders. A dissolves easily in water, while B does not. What can you conclude?
They have different properties, providing evidence that they may be different substances.
A student tears a piece of paper into small pieces. Another student burns a piece of paper. Which change is chemical, and how do you know?
Burning the paper is a chemical change because new substances are formed. Tearing the paper is a physical change because it changes only the size and shape, not the substance.
A student makes three mixtures: A. Salt completely dissolved in water B. Oil and water C. Chocolate milk that has been completely stirred. Which mixture does NOT belong with the other two? Explain.
Answer: B — oil and water. It is heterogeneous because the substances remain separate. A and C are homogeneous because they are evenly mixed throughout.