(Ch.7) Chemical Reactions Flashcards
What is a Chemical Reaction?
The transformation of one of more substances into different substances.
(think: atoms rearranging to form something new)
What are the six examples of chemical reactions that he gave?
- Burning of octane
- Rust
- Photosynthesis
- Burning natural gas
- Neutralizing stomach acid (taking an antacid pill)
- Baking bread
(You don’t need to memorize just re-read a few times)
What are four kinds of evidence of a chemical reaction?
- Formation of a solid (precipitate)
- Formation of a gas
- Color change
- Temperature change
Define “Precipitate.”
The formation of a solid from a non solid due to a chemical reaction.
What is a Chemical Equation?
An efficient way to represent chemical reactions.
Below is an example of a chemical equation.
1. What is the first half called? Describe what happens in this part of the equation.
2. What is the second half called? Describe what has happened in this part of the equation.
CH4(g)+2O2(g)-> CO2(g)+2H2O(g)
- These are the “reactants.” These chemicals are undergoing a rearrangement of their anatomical structure- thus changing.
- These are the “products.” These are the new substances formed from the previous reaction.
What does it mean when you see a symbol like this?
<-
->
The reaction may be reversible. (fun!)
What do these markings mean?
H2O(g)
H2O(l)
H2O(s)
These markings simply let the reader of the equation know what state of matter the substance currently is in. Gas, liquid, or solid.
Why do we balance chemical equations?
To make sure the quantities on each side of the equation are equal and correspond with the Law of Conservation of Mass.
How many atoms are in each element?
1. C4
2. 4C4
3. 4H
4. 4H2
- 4 Carbon atoms
- 4(4)= 16 Carbon atoms
- 4 Hydrogen atoms
- 4(2)= 8 Hydrogen atoms
What are three tips for balancing equations?
- Avoid balancing an element that is in multiple substances on one side. Come back to it.
- If an element is a free floating element, deal with it last.
- Treat polyatomic ions as a unit.
What can you NOT do when balancing equations?
NEVER change the subscript-it’ll change the entire substance. Only change the coefficient.
What is a Molecular Equation?
A chemical equation that shows the complete formulas of all the reactants and the products in the reaction. (normal one)
What is an Ionic Equation?
A ionic equation shows reactants and products as they are in solution. All soluble ionic compounds separate into constituent ions.
What is a Net Ionic Equation?
A net ionic equation shows only the substances that participate in the reaction. (get rid of the ones that cancel out, remove the spectator ions)
