Chemical Changes
What changes during a chemical change?
Original substance turns into a different substance with new properties
Name TWO things that could change in a physical change?
Shape and state of matter
What is an open system?
Explain and give an example.
Reacting vinegar with baking soda in a beaker.
There is nothing that will contain the products after the reaction happens. Any gas that is produced would go out in to the room.
Which one of these is a physical change and WHY?
A) Boiling an egg
B) Adding salt to water
C) Rusting iron
Adding salt to water is just dissolving the salt.
No new substance is formed.
It can be recovered if you evaporate the water.
Give an example of a HOMOGENEOUS MIXTURE.
Evenly mixed without being able to see the different parts.
Give TWO indicators of a chemical change.
Makes new substance
Energy change - light, heat, sound
Change in color
Gas production (bubbles)
Precipitate
What stays the same in a physical change?
molecular structure
What is an closed system?
Explain and give an example.
Reacting vinegar and baking soda in a bottle with a balloon on top.
The mass will stay the same throughout the entire reaction. The gas would be contained in the system.
Which one of these is a chemical change and WHY?
A) Adding food dye to water
B) Frying an egg
C) Breaking glass
Frying an egg is changing the chemical composition and making something new.
You can't get back the original egg in its original form.
Give an example of a SOLUTE and WHY.
Substance that is mixed into a solute that gets dissolved.
What are TWO things that happen when the bath bomb is added to water that indicates a CHEMICAL change?
Gas production (bubbles)
Change in temperature (colder)
New substance made (carbon dioxide)
What changes when cheese is melting?
State of matter
You are trying to make more carbon dioxide from a reaction of baking soda and citric acid.
If you increased the amount of water and the gas production STAYED THE SAME, what would be your next step?
Decrease the amount of water.
Which one of these is a physical change and WHY?
A) Using clay to make a pinch pot in art
B) Heating sugar water to make caramel
C) Mixing vinegar with baking soda
Making a pinch pot is taking the clay and making a new shape. No new substance is being formed.
What does it mean if something is INSOLUBLE?
Does not dissolve in a solute
When iron rusts, what TWO indicators are present to confirm a chemical change?
Change in color
New substance made (iron oxide)
Properties change (strength weaker)
Can a physical change go back to what it started as?
Explain.
Melting ice can be refrozen into an ice cube.
You are trying to make more carbon dioxide from a reaction of baking soda and citric acid.
If you increased the amount of citric acid and the gas production STAYED THE SAME, what would be your next step?
Increase the water
Have equal amounts of baking soda and citric acid
Which one of these is a chemical change and WHY?
A) Boiling pot of water making steam
B) Carbon turning into a diamond
C) Baking a cake
Baking a cake is making something new. The ingredients mix together and bubble to create the holes inside of the cake and the reaction can be reversed to get back the flour, eggs, and sugar.
What is matter?
Anything that has mass and takes up space.
What TWO types of energy are released when wood is burning?
Light (flame)
Heat
Sound (popping)
Give two examples of a physical change.
Tearing paper
You are trying to make your plant grow better.
What different things could you test to make them grow bigger?
How would you determine if you were successful?
Amount of water
Amount of light
Fertilizer
Measure the height daily
You are deciding on whether something is a chemical or a physical reaction.
List THREE indicators of a CHEMICAL reaction.
Makes new substance
Energy change - light, heat, sound
Change in color
Gas production (bubbles)
Precipitate
Compound is two elements chemically bound together with different properties of the original elements.
Mixture is two substances together in one spot, but not chemical bound together. Retain the same properties as the original elements.