Unit 3 Test Review

What is true about a chemical equation?

• the number of atoms can be different on the reactant and product side

• the atoms of each element should be the same on both the product and reactant side

• the elements can be different on the reactant and product side

• the substances in a chemical reaction stay the same

Which of the pictures below best represents a chemical equation that is not balanced?

• 
• 
• 
• 

Which equations below shows a new substance being formed?

• 2H₂O + O₂ ---> H₂O + O

• NH₃ + HCl ---> HCl + NH₃

• 2NaO + 2H₂O ---> 4NaOH + O₂

• 2Al + 3Mn + O₃ ---> Al + Mn + O₃

During a science lab, two students poured a white, powdered solid into a bag. Then they poured a colorless liquid into the same bag. They closed the bag and noticed that bubbles formed and the temperature started to decrease. What most likely happened?

• The substances reacted chemically.

• The liquid went through a rapid phase change.

• The student's hand was cold which made the substance turn cold.

• Some of the liquid started to freeze, making the bag cold.

The equation above represents a chemical reaction. How many atoms are represented in the products of this equation?

• 4

• 5

• 6

• 7

Which chemical formula has twice as many oxygen (O) atoms as potassium (K) atoms?

• KHCO₃

• KOH

• K₂SO₄

• KNO₃

How many total atoms are in the molecule of potassium acetate above?

• 8

• 7

• 9

• 5

What is the large number written before a chemical formula called?

• Coefficient

• Subscript

• Reactant

• Product

What is the small number written after a chemical symbol called?

• Coefficient

• Subscript

• Product

• Reactant

In the reaction methane + oxygen turns into carbon dioxide + water, the methane and oxygen are called _______________.

• reactants

• products

• neutrals

• energizers