Exam 2 Review

What is the formula for carbon dioxide?

• CH₄
• CO₂
• NaCl
• H₂O

How many oxygen atoms are in Al₂(SO₄)₃

• 4
• 12
• 7
• 24

Why do atoms bond?

• To create a new substance
• To become less chemically stable
• To become more chemically stable
• To gain more protons

When atoms bond, which subatomic particle is transferred or shared?

• nucleus
• neutron
• electron
• proton

Describe the relationship between the carbon and the hydrogens in a molecule of methane.

• The carbon donates electrons to the hydrogens in an ionic bond
• The hydrogens donate electrons to the carbon in an ionic bond
• They share electrons in a covalent bond
• The atoms do not react with each other

How do you know if a chemical change has occurred?

• If the substance changes from a solid to a liquid
• If a new substance is produced
• If the two substances separate

If two liquids are poured into a test tube and one settles to the bottom while the other rises to the top, did a chemical reaction occur?

• YES
• NO

If heat is added to a reaction and a new substance is formed, a ____________  ____________ has occurred.

• physical change
• chemical change

What could explain why the mass of the product is less than the mass of the reactants?

• There was no reaction
• The product was more dense than the reactants
• One of the products was a gas
• The Law of Conservation of Mass doesn't apply

How can you tell that an exothermic reaction has occurred?

• The container feels cooler after the reaction
• The container feels warmer after the reaction
• You cannot determine unless you have a thermometer