Understanding Chemical Reactions and Mass

What does the Law of Conservation of Mass state?

• Mass can be created during a chemical reaction.

• Mass is neither created nor destroyed during a chemical reaction.

• Mass is always lost during a chemical reaction.

• Mass doubles after a chemical reaction.

During a chemical reaction, what happens to the atoms involved?

• They are destroyed.

• They are rearranged.

• They disappear.

• They turn into energy.

Which of the following best represents the Law of Conservation of Mass in a chemical reaction?

• The total mass of reactants equals the total mass of products.

• The mass of products is always greater than the mass of reactants.

• The mass of reactants is always less than the mass of products.

• Mass is irrelevant in chemical reactions.

Which statement is true about atoms in a chemical reaction?

• Atoms are created.

• Atoms are destroyed.

• Atoms are rearranged.

• Atoms disappear.

What is a particle diagram used for in chemistry?

• To show the temperature of a reaction.

• To show the rearrangement of atoms during a chemical reaction.

• To measure mass.

• To calculate speed.

Which of the following is a correct word equation for the reaction of hydrogen and oxygen to form water?

• Hydrogen + Oxygen → Water

• Water → Hydrogen + Oxygen

• Hydrogen → Oxygen + Water

• Oxygen + Water → Hydrogen

In a balanced chemical equation, what must be equal on both sides?

• The number of molecules

• The number of atoms of each element

• The number of products

• The number of reactants

Which of the following is a balanced chemical equation for the formation of water?

Which of the following best describes a chemical reaction?

• Atoms are rearranged to form new substances.

• Atoms are destroyed to form new substances.

• Atoms are created from nothing.

• Atoms remain unchanged and do not interact.

If you start with 10 grams of reactants in a closed system, how much mass of products should you expect after the reaction?

• 0 grams

• 5 grams

• 10 grams

• 20 grams