9.1 Review

 Mg  +  ___ HCl  →   MgCl₂  +   H₂

• 1
• 2
• 3
• 4

Balance this equation-
__P₄ + __O₂ --> __P₂O₃

• it is already balanced
• 2, 1, 3
• 1, 2, 3
• 1, 3, 2

Endothermic reactions...

• release energy
• explode
• take in energy
• have higher energy in their reactants than the products

Exothermic reactions

• have higher energy in their products than their reactants
• release energy
• get cold
• are synthesis reactions

What is the law of conservation of mass?

• The amount of matter changes when reacted or changed.
• The mass of all reactants are changed during a physical or chemical change
• The mass of the reactants equals the mass of the products
• The mass of the products is different than the mass of the reactants.

How many oxygen atoms are in this chemical formula?

• 6 oxygen atoms
• 2 oxygen atoms
• 3 oxygen atoms
• 4 oxygen atoms

How many nitrogen atoms does NH₃ have?

• 1
• 2
• 3
• 4

The number in front of a compound or element is a 

• Subscript
• Coefficient
• Superscript
• Charge

What is the Law of Conservation of mass?

• Mass is created in a chemical reaction
• Mass is created in a physical change
• New chemicals formed from a chemical reaction have a larger overall mass than the original reactants
• Mass is never created or destroyed

Does this follow the law of conservation of mass:

Yes No

Na + F --> NaF

• Yes

• No