Chemical Equations 11/24/14

Chemical equations Starting materials called reactants are shown on the left of the arrow Ending materials called products are shown on right of the arrow NaCl + KOH  NaOH + KCl

Diatomic elements Some elements always come as a pair of atoms when in element form H 2, N 2, O 2, F 2, Cl 2, Br 2, I 2 Other elements sometimes come in unique amounts such as S 8 and P 4

Subscripts vs. Coefficients Subscripts are used to make stable compounds. They show how the elements bond with each other. – H 2 O and H 2 O 2 Coefficients tell how many of the compound are involved in the reaction. 2 H 2 O

Chemical equation symbols yields reversible reaction heat Δ reactants are heated Pressure pressure exceeding atmospheric pressure is used Catalyst a catalyst is used to speed up the rate of reaction

Compounds If the name uses prefixes it is a covalent compound. Determine subscripts using prefixes If the name does not use prefixes it is an ionic compound. Look up charges and criss cross to find subscripts

Compounds If the name of the compound doesn’t end in – ide, it includes a polyatomic ion. Put it in parenthesis and then criss cross charges. Sulfate= SO 4 -2 Hydroxide= OH -1

Compounds with special names: – Ammonia= NH 3 – Hydrogen peroxide= H 2 O 2 Acids: – Sulfuric= H 2 SO 4 – Hydrochloric=HCl – Nitric= HNO 3

States of matter symbols (s) solid (l) liquid (g) gas (aq) aqueous; dissolved in water solid, precipitate product gaseous product