Lesson 2: Chemical Equations

When wood is burned, the mass of the remaining ash is less than the mass of the original wood. Which statement best explains this result?

•    The ash has less volume than the paper.
• Some of the matter is destroyed during the reaction.
• The mass of the ash cannot be accurately determined.
• Some of the products of the reaction were given off as a gas.

Which substance is a product in this reaction?
2 HCl + CaCO₃ = CaCl₂ + H₂O + CO₂

• 2 HCl
• CaCO₃ 
• CaCl₂
• C

Which is a balanced chemical equation?

• CH₄ + 2 O₂ = CO₂ + 2 H₂O
• 2CH₄ + 2 O₂ = CO₂ + 2 H₂O
• CH₄ + O₂ = CO₂ + 2 H₂O
• CH + 2 O₂ = CO₂ + 2 H₂O

Which number completes the balanced chemical equation? 
4 Fe + ____ O₂ = 2 Fe₂O₃

• 2
• 1
• 3
• 4

What does a letter represent in a chemical equation/formula? (ex. H₂O)

• Element
• Number of Atoms
• Number of compounds
• A chemical formula

What are the small numbers in a chemical equation called? (ex H₂O)

• Exponents
• Subscripts
• Elements
• Coefficients

What are the big numbers in a chemical equation called? (2H₂O)

• Subscripts
• Exponents
• Elements
• Coefficients

What do the small numbers in a chemical equation represent? (ex H₂O)

• How many atoms of a given element
• They identify the element
• How many times the reaction occurs
• Nothing, they're just there.

Which is the correct set up for a chemical equation?

• Product > Reactant
• Reactant > Product

What does the law of conservation of matter say?

• Matter can not be created or destroyed, only changed.
• Matter can be destroyed, only when a chemical reaction occurs.
• Matter can only be created when a chemical reaction occurs.
• There is no such thing.