Question | Answer |
a shorthand notation that represents a compound or diatomic molecule | chemical formula |
the minimum amount of energy needed to start a reaction | activation energy |
ions in different compounds switch places | double-displacement reaction |
is written after an element in a chemical formula | subscript |
a substance that slows down or stops a chemical reaction | inhibitor |
is the number that goes in front of the chemical formula | coefficient |
speeds up a reaction | catalyst |
uses chemical symbols and formulas as a shortcut to describe a chemical reaction | chemical equation |
is a reaction in which one element takes the place of another element in a compound | single-displacement reaction |
Which of the following is an example of a chemical reaction?
A. a tire losing air
B. water boiling
C. a solid forming in a solution
D. ice melting | C |
What is O2 an example of?
A. chlorophyll
B. diatmoic molecules
C. chemical bond
D. sulfuric acid | B |
Which of the following is an example of a single-displacement reaction?
A. Fe + 2HCl -> FeCl2 + H2
B. 2Mg + O2 -> 2MgO
C. 2H2O2 -> 2H2O + O2
D. NaOH + HCl -> NaCl + H2O | A |
How can the rate of reaction be increased?
A. decreasing the concentration of the reactants
B. grinding a solid reactant into a powder
C. lowering the temperature of the reactants
D. raising the temperature of the products | B |
How many atoms are represented in the formula CaCO3?
A. 3
B. 4
C. 5
D. 6 | C |
What is the difference between a synthesis reaction and a decomposition reaction? | A synthesis reaction takes 2+ substances to build a compound, while a decomposition reaction breaks down a compound into 2+ substances.
Ex) Synthesis: A + B -> AB
Decomposition: AB -> A + B |
Which of the following describes chlorophyll breaking down into new substances?
A. chemical substance
B. chemical reaction
C. chemical mixture
D. chemical solution | B |
What is true of the new substances formed in a chemical reaction?
A. properties differ from original substances
B. properties are the same as original substances
C. all substances have original properties
D. no substances have original properties | A |
Which of these is a sign of a chemical reaction?
A. steam on a skating rink
B. ice melting on the ground
C. a dissolving solid
D. a solid precipitate | D |
How can you be sure a chemical reaction is happening?
A. a solid dissolves
B. a new substance is formed
C. water turns to steam
D. a mixture is made | B |
Which of the following is an example of a diatomic molecule?
A. O2
B. CO2
C. H2O2
D. O3 | A |
When chemical bonds break, what do atoms do?
A. change into other atoms
B. become energy
C. rearrange
D. disappear in the reaction | C |
What does a prefix in a chemical formula tell you about an element?
A. number of atoms
B. number of chemicals
C. number of molecules
D. number of elements | A |
What happens to atoms in a chemical reaction?
A. they are sometimes lost and never rearranged
B. they are sometimes lost, gained, or rearranged
C. they are never lost of gained, just rearranged
D. they are lost or gained and never rearranged | C |
What must be done for a chemical equation to be balanced?
A. all molecules must be counted
B. all chemicals must be equal
C. all atoms must be counted
D. all atoms must be disconnected | C |
Which of the following usually increases the rate of a reaction?
A. lowering the concentration
B. grinding a solid reactant into powder
C. lowering the temperature of the reactants
D. raising the temperature of the products | B |
What happens in an endothermic reaction?
A. energy is destroyed
B. energy is released
C. energy is created
D. energy is taken in | D |
an element replaces another element | single-displacement reaction |
ions from 2 compounds exchange places | double-displacement reaction |
2 substances combine forming a new compound | synthesis reaction |
a compound breaks down into new substances | decomposition reaction |
the force that holds 2 atoms together | chemical bond |
When _________ bump into 1 another with enough energy, chemical bonds break. | molecules |
When chemical bonds break, the atoms rearrange to form new _____. | bonds |