Unit 7 - Chemical Reactions Review

24 Questions | By Haszshe | Updated: Mar 22, 2022 | Attempts: 143

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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.

Questions and Answers

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