8th Grade Intro to Chem. 4.1-4.3 Review

The Law of Conservation of Matter

• tells how many atoms of an element are contained in one molecule or formula unit.

• the starting materials in a chemical reaction

• the new substances that are formed in a chemical reaction

• A law stating that atoms are not created or destroyed during a chemical reaction.

Is the equation balanced?: 2H₂O + O₂ --> 4MgO + 3Fe

• yes

• no

Balance this equation

_Al +_HCl --> _H₂ +_AlCl₃

• 2,6,3,2

• it's already balanced

• 4,12,3,4

• 2,1,4,5

The coefficient in 3H₂O is

• 6

• 5

• 2

• 3

How many atoms of carbon (C) are in C₆H₁₂O₆?

• 3
• 6
• 12
• 24

How many Sodium (Na) are in 6NaCl?

• 1
• 12
• 6

How many Hydrogen are in 4H₂O?

• 6
• 8
• 2
• 4

Balance the following equation:

___ H₂+ ___ O₂→___ H₂O

• 1, 1, 3

• 2, 2, 2

• 1, 2, 1

• 2,1, 2

Balance the following equation:

___ SeCl₆+ ___ O₂→___ SeO_{2+____}Cl₂

• 1, 1, 1, 3

• 2, 1, 2, 1

• 1, 2, 1, 2

• 2, 2, 2, 4

Balance this equation
_N₂ + _H₂ --> _NH₃

• 1,2,3
• 1,3,2
• 1,1,2
• 2,1,1