Unit 7 - Chemical Reactions Review
In science, a chemical reaction is a process that leads to the transformation of one set of chemical substances to another. This typically involves the changing of electron positions in the manipulation of chemical bonds between atoms.
- 1.What type of reaction produces a precipitate?
- A.
Synthesis
- B.
Single displacement
- C.
Double displacement
- D.
Decomposition
- 2.____ is a way to describe a chemical reaction using chemical formulas and symbols.
- A.
Synthesis
- B.
A physical law
- C.
The law of conservation of matter
- D.
A chemical equation
- 3.An insoluble compound that comes out of solution during a double displacement reaction is called a _____.
- A.
Reactant
- B.
Solvent
- C.
Precipitate
- D.
Catalyst
- 4.What does it mean for a chemical equation to be balanced?
- A.
The number of reactants is equal to the number of products.
- B.
The reactants and products are written with the same coefficients.
- C.
The same number of atoms of each element is on both sides of the equation.
- D.
The solid products weight the same as the reactants.
- 5.In chemical equations, ______ represents the number of units of each substance.
- A.
Precipitates
- B.
Products
- C.
Reactants
- D.
Coefficients
- 6.The chemical formula for a compound tells _____.
- A.
How stable the compound is
- B.
What type of chemical bond it forms
- C.
How electrons are arranged
- D.
What elements it contains
- 7.If electric current passes through water and initiates a decomposition reaction, what are the expected products?
- A.
Oxygen and water
- B.
Hydrogen and oxygen
- C.
Hydrogen peroxide
- D.
Hydrogen oxide
- 8.When iron combines with oxygen and water in the air to form rust, what substance in the reaction is the product?
- A.
Iron
- B.
Rust
- C.
Water
- D.
Oxygen
- 9.As a result of the experiments of Lavoisier, you know that in a chemical reaction the masses of the products _____.
- A.
Is less than the mass of the reactants
- B.
Always equals the mass of the reactants
- C.
Cannot be predicted based on the mass of the reactants
- D.
Is twice as great as the mass of the reactants
- 10.New substances produced by a chemical reaction are ____.
- A.
Products
- B.
Resultants
- C.
Reactants
- D.
Coefficients
- 11.In a ______ reaction, two or more substances combine to form another substance.
- A.
Single displacement
- B.
Double displacement
- C.
Decomposition
- D.
Synthesis
- 12.A change in which one or more substances are converted into new substances is a _____.
- A.
Nuclear reaction
- B.
Chemical reaction
- C.
Chemical fusion
- D.
Physical change
- 13.A(n) _____ is a substance that speeds up a chemical reaction without being permanently changed itself.
- A.
Catalyst
- B.
Inhibitor
- C.
Exotherm
- D.
Endotherm
- 14.Why is oxygen written with a subscript 2?
- A.
It usually exists as a diatomic molecule.
- B.
Its mass is twice as great as the reactants'.
- C.
There are two times as many oxygen atoms as reactant atoms.
- D.
Its mass increases by two times as a result of the reaction.
- 15.The law of conservation of mass states that _____.
- A.
In a chemical reaction, matter is not created or destroyed, but is conserved.
- B.
Matter can be created and destroyed but does not change forms.
- C.
In a chemical reaction, efforts should be made to preserve rare elements without changing them.
- D.
In a chemical reaction, the final mass of the products is always greater than the starting mass of the reactants.
- 16.Which of the following is a chemical reaction?
- A.
Water freezing into ice
- B.
Water evaporating from salt water leaving salt crystals
- C.
Dew forming on grass
- D.
Rust forming on a car body
- 17.Some elements usually exist in combinations of two atoms. These combinations are called ______.
- A.
Diatomic molecules
- B.
Coefficients
- C.
Ions
- D.
Isotopes
- 18.Identify the following as either endothermic or exothermic. The temperature of the beaker holding the reacting substances is increased.
- A.
Endothermic
- B.
Exothermic
- 19.Identify the following as either endothermic or exothermic. The temperature of the beaker holding the reacting substances is decreased.
- A.
Endothermic
- B.
Exothermic
- 20.Identify the following as either endothermic or exothermic. Frost formed on the outside of the beaker holding the reacting substances.
- A.
Endothermic
- B.
Exothermic
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