2.2 Conservation of Mass in Chemical Equations

chemistry

Writing Chemical Equations

The simplest form of chemical equation is a word equation

  • Not much information other than the elements/compounds involved
  • Potassium metal + oxygen gas --> potassium oxide
  • reactants appear on the left of the arrow and products appear on the right
A skeleton equation shows the formulas of the elements/compounds
  • Shows atoms, but not quantities of atoms
  • K(s) + O2 (g)--> K2O(s)
A balanced chemical equation shows all atoms and their quantities
  • Balancing ensures that the number of each atom is the same on both sides of the reaction arrow
  • Always use the smallest whole number ratio
  • 4K(s) + O2 (g)--> 2K2O(s)

States of matter are indicated in chemical equations.

Letters indicate the state of each compound

(aq) = aqueous/dissolved in water

(s) = solid

(l) = liquid

(g)= gas