Chemical Reactions and Equations

The law of conservation of mass states that....

• Matter can be made
• Matter can be destroyed
• Matter can neither be made or destroyed

Is this balanced?...
Al + O₂ --> 2Al₂O₃

• Yes!
• NO!

Balance this equation...
HgO --> 2Hg + O₂

• It is balanced 
• 2HgO --> Hg + O₂
• 2HgO --> 2Hg + O₂

At the end of chemical reactions, what is the total mass of the reactants compared to the total mass of the products?

• the product is doubled
• the product is half the mass of the reactants
• the mass is the same
• the mass changes depending on the reaction

How many valence electrons does magnesium have?

• 6

• 12

• 2

• 10

What are valence electrons?

• electrons in the outermost energy level

• electrons in the innermost energy level

• positively charged ions

• energy used for attraction in a shell

What does the symbol inside the circle mean?

• "yields, or produces"

• "dissolved in water"

• "forms a precipitate"

• "released as a gas"

When balancing this equation, Fe + Cl₂ → FeCl₃, the correct coefficient for Cl₂?

• 1

• 2

• 3

• 4

Balance this equation, CaCO₃(s) → CaO(s) + CO₂(g)?

• 3,1,2

• 1,1,1

• 1,3,1

• 2,6,3

The blue numbers in the image below represent ________

• I don't know, and don't want to try
• coefficients
• subscripts
• none of the answers are correct