Convert each compound name into its chemical formula, then balance the equation. 1. aluminum chloride + calcium hydroxide  aluminum hydroxide + calcium chloride

2AlCl3 + 3Ca(OH)2 --> 2Al(OH)3 + 3CaCl2

Explanation:

aluminum chloride + calcium hydroxide --> aluminum hydroxide + calcium chloride

AlCl3 + Ca(OH)2 --> Al(OH)3 + CaCl2

Note: Al forms an ion of charge +3, Cl forms ion of charge -1, OH forms ion of -1, and Ca forms ions of charge +2. So when you combine 2 of these into ions, (must be one positive, one negative for ionic compounds), make sure the net charge at the end =0.

For example, Al ions have a charge of +3, so it needs 3 Cl- ions to eliminate the negative charge, so aluminium chloride is AlCl3.

Now balance the equation. make sure both sides have the equal no. of ions.

start with Cl. the reactant side has 3 Cl ions, while the product side has 2. So, the lowest common multiple is 6. Multiply AlCl3 by 2, and CaCl2 by 3 to get 6 Cl ions on each side.

2AlCl3 + Ca(OH)2 --> Al(OH)3 + 3CaCl2

Now the reactant side has 2 Al ions. So, multiply the Al(OH)3 on the product side by 2 to balance out Al ions.

2AlCl3 + Ca(OH)2 --> 2Al(OH)3 + 3CaCl2

Finally, the product side has 6 OH- ions, so multiply 3 on Ca(OH)2 from the reactant side to balance out the OH- ions.

2AlCl3 + 3Ca(OH)2 --> 2Al(OH)3 + 3CaCl2

Recount the ions to make sure it is correctly balanced! :)

Balanced chemical reaction: 2K + S → K₂S, product of reaction is potassium sulfide.
There are same number of atoms on both side of chemical reaction, two potassium atoms and one sulfur atom.
Potassium oxidizes from zero to +1 oxidation number and sulfur is reduced from zero to -2 (gain two electrons).