Presentation on theme: "Balancing Equations: Purpose: Students will be able to balance chemical equations. Warm-up: What’s the difference between the three formulas below? Cl2."— Presentation transcript:
1 Balancing Equations:Purpose: Students will be able to balance chemical equations.Warm-up: What’s the difference between the three formulas below?Cl Cl Cl2one moleculetwo atomstwo molecules
2 Counting AtomsMolecules may also have brackets to indicate numbers of atoms. E.g. Ca(OH)2Notice that the OH is a groupThe 2 refers to both H and OOHCaHow many of each atom are in the following?a) NaOHb) Ca(OH)2c) 3Ca(OH)2Na = 1, O = 1, H = 1Ca = 1, O = 2, H = 2Ca = 3, O = 6, H = 6
3 Balancing Equations: MgO Law of Conservation of Mass: matter can neither be created or destroyedSince atoms cannot be created or destroyed, they are only rearranged in a chemical reactionThe number of atoms must be the same on both sides!
4 Balancing Equations: MgO Example: Magnesium + OxygenMg + O2 MgOOMg+MgOHowever, this is not balancedLeft: Mg = 1, O = 2Right: Mg = 1, O = 1
5 Balancing Equations: MgO +MgOHowever, this is not balancedLeft: Mg = 1, O = 2Right: Mg = 1, O = 1From: Mg + O2 MgO2Mg + O2 2MgO is correctMg + ½O2 MgO is incorrectMg2 + O2 2MgO is incorrect4Mg + 2 O2 4MgO is incorrect
6 Balance Equations P4 + O2 P4O10 Li + H2O H2 + LiOH Bi(NO3) K2S Bi2S KNO3d) C2H O2 CO H2O52222363.523e) C2H O2 CO H2O2746