Dr. Miller 4th period

A chemical reaction is balanced when

• both sides have the same elements
• Both sides have the same  number of atoms
• Same subscripts
• Same coefficients

Which are the reactants in the following reaction?
2Mg + O₂ ---> 2MgO 

• Mg and O
• MgO
• Mg and MgO
• O and MgO

24 g of magnesium reacts with 38 g of fluorine to produce _____ g magnesium fluoride

• 62 
• 38
• 24
• 14

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

Bob puts 200 grams of ice into a pitcher with 900 grams of water. He gets distracted and comes back later to find that the ice has melted in the water. How many grams of water does Bob now have in the pitcher?

• 200 g
• 700 g
• 1,100 g

What will weigh more when a chemical change is complete?  The reactants before the chemical reaction, or the product after the reaction is complete?

• They both will weigh the same
• The product always weighs more than the reactant
• The reactant will weigh more than the product
• They both will loose mass after the reaction

Measure of the amount of matter 

• mass
• volume
• weight
• density

In a reaction A + B ----> C,  reactant A has 5g and product  C has 9g. How many grams does reactant B should have? 

• 4g
• 5g
• 9g
• 14g

The coefficient in  3H₂O is

• 6
• 2
• 3
• 5

The number to the lower side of an element is a 

• Subscript
• Superscript
• Coefficient
• Charge