C3

• What does the law of conservation of mass state?

  No atoms are lost or made in reactions
• What does a balanced chemical equation ensure?

  Same number of atoms on both sides
• What does a balanced chemical equation imply about mass?

  Mass of reactants equals mass of products
• Why might a reaction appear to involve a change in mass?

  Gas reactant or product not accounted for
• What happens when a metal reacts with oxygen?

  Mass of metal oxide product is greater
• What is always present in chemical measurements?

  Some uncertainty about the result
• What unit is used to measure chemical amounts?

  Moles
• How is the mass of one mole of a substance related to its relative formula mass?

  It is numerically equal to its relative formula mass
• What is the Avogadro constant?

  $6.02 \times 10^{23}$ per mole
• What must be true about the total moles of one element in a balanced equation?

  They must be the same on both sides
• What is a limiting reactant?

  The reactant that is used up first
• How does a limiting reactant affect product yield?

  Limits the amount of product produced
• How is concentration of a solution measured?

  Mass per given volume of solution
• What is the formula to calculate mass of solute in a solution?

  mass = concentration x volume
• What happens to concentration with a smaller volume of solute?

  It gives a higher concentration
• What happens to concentration with a larger mass of solute?

  It gives a higher concentration
• What effect does a larger volume of solute have on concentration?

  It gives a lower concentration
• What effect does a smaller mass of solute have on concentration?

  It gives a lower concentration