Definitions
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Define a physical change.
A physical change is when matter changes form, but not chemical make up.
When I crumple a piece of paper in my hand, is this a physical change or chemical change?
This is a physical change. The paper changed shape, but it's still paper.
The pH scale measures acids and bases. Is an acid below 7 or above 7?
An acid is anything below 7 on the pH scale.
What happens when you put a raw egg into vinegar?
DOUBLE POINTS FOR THE SCIENTIFIC EXPLANATION!
The shell will dissolve.
Scientific Explanation: The vinegar is an acid. It reacts with the shell and turns it into calcium and carbon dioxide gas. That's why you see it bubble and why a bunch of white paste comes off of it.
How do you make a solution?
Dissolve something in a liquid.
Define a chemical change.
A chemical change is when a substance becomes new substances. The new substances are chemically different than the original.
Give examples of physical changes. Each example is worth 50 points. Give 4 or more examples to get all 200 points.
(you can't get more than 200 points).
Some examples might be cutting paper, hammering gold, breaking glass, freezing water, taking a bite of an apple, etc.
The pH scale measures acids and bases. Is a base below 7 or above 7?
A base is anything above 7 on the pH scale.
What happens if you leave plaster of paris or cement underwater?
It will harden because it doesn't dry, it cures.
This is also why you DON'T put it down the sink.
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Why do objects sink or float?
They are more dense (sink) or less dense (float) than water. That means their atoms are packed together more tightly or less tightly than water's atoms.
Define an endothermic reaction.
An endothermic reaction is a chemical reaction that uses up heat. The substance should get colder.
You can also say it takes in heat.
When a firework explodes in the air, is this a chemical change or a physical change?
This is a chemical change. The chemicals in the firework (similar to gunpowder) explode. They are lost and new chemicals (like smoke and ash) are made.
What if a substance is exactly 7 on the pH scale? What do we call it?
A substance that is exactly 7 pH is neither an acid nor a base. It is neutral.
When we bake bread, the yeast performs a chemical reaction. It takes ______ and turns it into ethyl _________ and ___________. This is why bread has bubbles in it.
(Each blank is worth 100 points)
When we bake bread, the yeast performs a chemical reaction. It takes sugar and turns it into ethyl alcohol and carbon dioxide (CO2). This is why bread has bubbles in it.
What is a non-Neutonian fluid?
A substance that acts like a liquid when left alone but when pressure is applied to it, it acts like a solid.
Define an exothermic reaction.
An exothermic reaction is a chemical reaction that creates heat. The substance should get hotter.
You can also say it gives off heat.
Give examples of chemical changes. Each example is worth 100 points. Give 4 or more examples to get all 400 points.
(you can't get more than 400 points).
Some examples of chemical changes are a log burning into ash and smoke, a firework exploding, baking soda and vinegar reacting, vinegar dissolving an eggshell, acetone dissolving styrofoam, etc.
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How do you change something's pH?
Add an acid or a base to it. An acid will lower its pH. A base will raise it.
Hydrogen peroxide reacts with ______ and turns into ________ and _________. Yeast can speed up this process. We call things that speed up chemical reactions ________.
(Each blank is worth 100 points.)
Hydrogen peroxide reacts with light and turns into water (H2O) and carbon dioxide (CO2). Yeast can speed up this process. We call things that speed up chemical reactions catalysts.
What three things make up atoms?
Protons, neutrons, and electrons.
Neutralization happens when an acid and a base cancel each other out. The result is a substance with a neutral pH. It isn't an acid or a base.
What is the Law of Conservation of Matter?
In a chemical reaction, no matter is created or destroyed. You have exactly the same amount of matter, it is just changed into new substances.
Our tongues are designed to detect acids and bases. Why might this have been helpful in the past?
Our tongue is able to detect acids as a sour taste. They detect bases as a bitter taste. This helped people long ago to stay away from dangerous foods as many poisonous foods or rotten foods were bitter or sour.
What are the chemical names of vinegar and baking soda?
Vinegar is known as acetic acid and baking soda is know as sodium bicarbonate.
How do you super saturate something?
First, dissolve as much of a solute as possible into the solution. You're done when you can mix it but no more will dissolve. Then, heat up the solution. This causes the atoms of the liquid to spread out and more solute can be dissolved between them. Dissolve as much as possible again. You have a super saturated solution!