Calculations With Mass

• What is the conservation of mass?

  In a chemical reaction, atoms are not created or destroyed, just rearranged, so no atoms are made or lost during a chemical reaction. The mass before the reaction must equal the mass after the reaction IN A CLOSED SYSTEM
• When a metal forms a metal oxide, why does the mass increase?

  Atoms from gaseous oxygen have been added
• When an acid reacts with a metal, why does the mass decrease?

  A gas is produced and escapes
• What is relative formula mass?

  The sum of the relative atomic masses of each atom in a substance
• What are the 4 state symbols and what do they stand for?

  Solid - (s)

  Liquid - (l)

  Gas - (g)

  Aqueous - (aq) dissolved in water
• How can you tell when a symbol equation is balanced?

  The number of atoms of each element is the same on both sides.
• What is a mole?

  Mass of a substance that contains 6.02x10 to the power of 23 particles
• Give the value for Avogadro's constant.

  6.02 x 10 to the power of 23
• What is a limiting reactant?

  The reactant that is completely used up in a chemical reaction.
• How do you convert a volume reading in cm3 to dm3?

  Divide by 1000
• If the amount of solute in a solution increases what happens to its concentration?

  Increases
• If the volume of water in a solution is increased what happens to its concentration?

  Decreases