Law of Conservation of Mass 21-22

Matter can not be created nor destroyed: it can only be

• Destroyed a little bit
• Invisible
• Transformed, changed
• None of the above

Which of these is not a chemical reaction?

• Burning of wood
• Milk going bad
• Mixing vinegar and baking soda
• Melting of ice

A precipitate is a 

• liquid that forms when two solids are reacted
• a solid that forms when two liquids are mixed
• a gas that forms when vinegar and baking soda react
• a change of color in a solution

If reaction starts with 20g of reactants it should produce 

• a total of 40g of products
• a total of 10g of products
• a total of 80 g of products
• a total of 20g of products

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

What do we call the chemicals that result from a chemical reaction?

• reactants

• products

• subscripts

• coefficients

________ are the starting substances in a chemical equation.

• Reactants

• Producer

• Reaction

• Products

The coefficient in  3H₂O is

• 6
• 2
• 3
• 5

How many oxygen atoms are in this chemical formula?

• 6 oxygen atoms

• 2 oxygen atoms

• 3 oxygen atoms

• 4 oxygen atoms

Which Chemical Equation is Balanced?

• Fe₄+O₂------4FeO₂+O₂

• 2H₂+O₂-----2H₂O

• 3Cr+4O₂-----2Cr₂O₃