1. NO 3 - - All nitrates are soluble. Cl - - All chlorides are soluble except AgCl, Hg 2 Cl 2, and PbCl 2. SO 4 2- - Most sulfates are soluble. Exceptions include BaSO 4, PbSO 4, and SrSO 4. CO 3 2- - All carbonates are insoluble except NH 4 + and those of the group 1 elements OH - - All hydroxides are insoluble except those of the Group 1 elements, Ba(OH) 2, and Sr(OH) 2. Ca(OH) 2 is slightly soluble. Solubility Rules of Ionic Solids in Water (important when writing states)

2. Step 1: Write the equation and balance it if necessary NaCl(aq) + AgNO 3 (aq) → AgCl(s) + NaNO 3 (aq) Step 2: Split the ions. (Only compounds that are aqueous are split into ions.) Leave all compounds with (s), (l), or (g) unchanged. Na + (aq) + Cl - (aq) + Ag + (aq) + NO 3 - (aq) → AgCl(s) + Na + (aq) + NO 3 - Step 3: Cancel out spectator ions. (Spectator ions are ions that remain the same in their original states before and after a chemical reaction.) Step 4: Write a balanced ionic equation Ag + (aq) + Cl - (aq) → AgCl(s) Writing ionic equations

3. Let's determine the empirical formula for a compound with the following elemental composition: 40.00% C, 6.72% H, 53.29% O. 1- Find the moles of all the atoms given [C] [H] [O] n = 40/12 = 3.333 n = 6.72/1 = 6.72 n = 53.29/16 = 3.331 Finding Empirical Formula 2 - Divide each mole value by the smallest number of moles calculated. Round to the nearest whole number. [C] [H] [O] 3.333/3.333 = 1 6.72/3.333 = 2 3.331/3.333 = 1 So the empirical formula is CH 2 O

4. For a compound which have empirical formula is CH 2 O the relative molecular mass = 60 What is the molecular formula? Empirical formula mass = 30 Molecular formula mass = 60 Molecular formula mass / empirical formula mass = 60/30 = 2 So: Molecular formula = (CH 2 O)*2 = C 2 H 4 O 2