Vocabulary for Chemical Reactions

Vocabulary for Chemical Reactions

Reactants

• H and O are NOT reactants. These just describe the elements that exist before and after the reaction.

• H₂O₂ IS a reactant. It is a MOLECULE that exists only before the reaction takes place.

Products

• H and O are NOT products. These just describe the elements that exist before and after the reaction.

• O₂ & H₂O ARE products. They are MOLECULES that exists only after the reaction takes place.

Sample Questions

• Question: How many hydrogen atoms are involved in this reaction?

• Answer: 4 (count the H atoms on only one side of the reaction)

Sample Questions

• Question: How many H₂O molecules are produced by this reaction?

• Answer: 2 (see the picture - also the coefficient in front of H₂O tells us this)

Reactants

• C, S, and Cl are NOT reactants. These just describe the elements that exist before and after the reaction.

• CS₂ and Cl₂ ARE reactants. These are the MOLECULES that exist before the reaction takes place.

Products

• C and Cl are NOT products. These just describe the elements that exist before and after the reaction.

• CCl₄ and S ARE products. In this case, S is a product because it does exist by itself (not in a compound) after the reaction.

Sample Questions

• Question: How many chlorine ATOMS are involved in this reaction?

• Answer: 4 (count the Cl ATOMS on only one side of the reaction - an atom is represented by a single circle)

Sample Questions

• Question: How many chlorine MOLECULES are needed for this reaction?

• Answer: 2 (a chlorine MOLECULE is made of two chlorine atoms - Cl₂ is a chlorine molecule)

Multiple Choice

The products

• exist before a reaction

• exist after a reaction

• tells you the number of atoms in a compound

• tells you the number of molecules in the reaction

Multiple Choice

The subscript

• exist before a reaction

• exist after a reaction

• tells you the number of atoms in a compound

• tells you the number of molecules in the reaction

Multiple Choice

The reactants

• exist before a reaction

• exist after a reaction

• tells you the number of atoms in a compound

• tells you the number of molecules in the reaction

Multiple Choice

The coefficient

• exist before a reaction

• exist after a reaction

• tells you the number of atoms in a compound

• tells you the number of molecules in the reaction

Multiple Select

Select ALL the reactants.

• Na

• Cl₂

• NaCl

• Cl

Multiple Select

Select ALL the products.

• Na

• Cl₂

• NaCl

• Cl

Multiple Choice

How many chlorine atoms are involved in this reaction?

• 1

• 2

• 3

• 4

Multiple Choice

How many sodium chloride molecules are formed in this reaction?

• 1

• 2

• 3

• 4

Multiple Select

Select ALL the reactants.

• CH₄

• O₂

• H₂O

• CO₂

Multiple Select

Select ALL the products.

• CH₄

• O₂

• H₂O

• CO₂

Multiple Choice

How many oxygen atoms are involved in this reaction?

• 1

• 2

• 3

• 4

Multiple Choice

How many oxygen molecules are needed to make this reaction happen (see reactants).

• 1

• 2

• 3

• 4