Physical vs. Chemical
Breaking a glass bottle, melting ice, and tearing paper are all examples of this type of change, where no new substance is formed.
What is a physical change?
Seeing bubbles form when mixing baking soda and vinegar is a sign that this state of matter was produced.
What is a gas?
The starting ingredients or materials in a chemical reaction are called this.
What are reactants?
When bread is placed in a toaster and turns black if left too long, this process is occurring.
What is burning (or combustion / charring)?
The Law of Conservation of Mass states that matter cannot be created or this in a chemical reaction.
What is destroyed?
Unlike a physical change, a chemical change always creates one or more of these.
What is a new substance?
When an iron bicycle is left outside in the rain and turns reddish-brown, this process has taken place.
What is rusting (or oxidation)?
The end result of a chemical reaction are known as these.
What are products?
An apple turning brown after being sliced and exposed to air is an example of a chemical reaction with this element in the atmosphere.
What is oxygen?
When the new substance absorbs thermal energy and feels cooler than the surroundings.
What is an endothermic reaction?
Baking a cake is a chemical change, but melting chocolate to put on top of the cake is this type of change.
What is a physical change?
A glow stick lights up when snapped because energy is being released in this form during the reaction.
What is light energy?
In a written chemical equation, this symbol is placed between the reactants and the products to mean "yield" or "produce".
What is an arrow (-->)?
Plants use sunlight, water, and carbon dioxide to make food and oxygen in this famous chemical reaction.
What is photosynthesis?
When the new substance releases thermal energy and feels warmer than the surroundings.
What is an exothermic reaction?
Dissolving salt into water is considered a physical change because you can get the salt back using this process.
What is evaporation (or boiling)?
When two liquid solutions are mixed, sometimes this will form. It is is a solid, insoluble substance, meaning that it does not dissolve in the liquid.
What is a precipitate?
Vinegar + Baking Soda --> Carbon Dioxide + Water + Sodium Acetate : carbon dioxide is one of these.
What is a product?
Digestion in your stomach relies on these chemical substances to break down food into smaller nutrients.
What are acids (or enzymes)?
If you mix two liquids with a combined mass of 50 grams in a sealed container, the total mass after the reaction will equal this.
What is 50 grams?
Burning a piece of wood is a chemical change because you cannot easily get the original wood back by doing this kind of process.
What is reverse it (or turn it back into wood)?
If two clear liquids are mixed together and suddenly turn bright blue, this unexpected change is a strong sign of a chemical reaction.
What is a color change?
In a reaction where hydrogen gas and oxygen gas combine to make water, water is called this.
What is the product?
Bread dough rises because living yeast cells release bubbles of this gas during a chemical reaction.
What is carbon dioxide (CO2)?
When you burn a piece of wood, the matter or (ash) escapes into the air as this.
What is smoke (or gas)?