When two or more elements or compounds combine together to form new compounds with different properties a chemical reaction has occurred
Chemical reactions are written using a chemical equation • 2Mg + O2 2MgO “yields” reactantsproducts
Law of Conservation of Mass The mass of the productsMUST be equal to the mass of the reactants.
When you write a chemical equation, you MUST observe the law of conservation of mass – the equation MUST be balanced
2Mg + O2 2MgO Mg – 2 Mg – 2 O – 2 O – 2 Br2 + NaI I2 + NaBr Br – 2 Br -1 NO! Na – 1 Na – 1 I – 1 I - 2 YES!
Is this chemical equation balanced? Na + AlCl3NaCl + Al
Is this chemical equation balanced? KBr + Cl2KCl + Br2
Is this chemical equation balanced? H2O2 H2O + O2
Balance these chemical equations: N2 + H2 NH3 KClO3KCl + O2 NaCl + F2 NaF + Cl2 H2 + O2 H2O Pb(OH)2 + HCl H20 + PbCl2
Balance these chemical equations: AlBr3 + K2SO4KBr + Al2(SO4)3 CH4 + O2 CO2 + H2O C3H8 + O2 CO2 + H2O CO2 + H2O C6H12O6 + O2 C8H18 + O2 CO2 + H2O