Unit 3 Chemical Reactions Exam Review

What is the right part of a chemical equation called...
2H_{2 +} O₂ --> 2H₂O

• Reactants
• Products 
• Yields 
• Chemical Equation 

What is the left part of a chemical equation called?
2H_{2 +} O₂ --> 2H₂O

• Reactants
• Products 
• Yields 
• Chemical Equation 

What does the Law of Conservation of Mass state?

• Matter cannot be gained or lost in a chemical reaction.
• Matter can only be lost in a chemical reaction.
• Matter can only be gained in a chemical reaction.
• Matter can be gained and lost in a chemical reaction. 

Balance this equation

_Al +_HCl --> _H₂ +_AlCl₃

• 2,6,3,2

• it's already balanced

• 4,12,3,4

• 2,1,4,5

How many HCl molecules do you need to balance this equation? 
Mg +  __HCl --->  MgCl₂ + H₂

• 1
• 2
• 3
• 4

What is the little number after an element in a chemical equation called.
Example: H₂

• Coefficient 
• Subscript
• Atom
• Equation

In the equation, 2Mg + O₂ ---> 2MgO, which are the reactants?

• Mg and O

• Mg and MgO

• MgO

• O and MgO

Balance this equation:

H₂ + Cl₂ ---> HCl

• It is balanced.

• H₂ + Cl₂ ---> 2HCl

• 3H₂ + Cl₂ ---> 6HCl

• H₂ + 3Cl₂ ---> 6HCl

Balance this equation:

HgO ---> 2Hg + O₂

• It is balanced.

• 2HgO ---> 2Hg + O₂

• 2HgO ---> Hg + O₂

• HgO ---> Hg + 2O₂

Balanced this equation:

Sb₂S₃ + O₂ ---> Sb + SO₂

• It is balanced.

• Sb₂S₃ + O₂ ---> 2Sb + SO₂

• Sb₂S₃ + 3O₂ ---> 2Sb + 3SO₂

• 3Sb₂S₃ + 3O₂ ---> 2Sb + SO₂