Solubility Rules and Precipitation Reactions Chapter 7 Reactions

Solubility Rules and Precipitation Reactions Chapter 7: Reactions in Aqueous Solutions!

Not all ionic compounds dissolve! Instead of doing experiments all the time to see which ones will dissolve, we use The solubility rules.

Solubility Rules All nitrates (NO 3 -) are soluble. 2. All ammonium (NH 4+) or alkali (Li+, Na+, K+, Rb+, Cs+, Fr+) compounds are soluble. 1. 3. All carbonates (CO 32 -), phosphates (PO 4 3 -) and hydroxides (OH-) are insoluble except with the cations in Rule #2. 4. All chlorides (Cl-), bromides (Br-), and iodides (I -), are soluble except with Ag+, Pb 2+, or Hg+. 5. All sulphates (SO 42 -) are soluble except with Ca 2+, Sr 2+, Ba 2+, Ra 2+, Pb 2+,

Solubility Rules Con’t 6. All acetates (CH 3 COO) are soluble except Fe 3+ 7. Except for rule 1 and 2, carbonates, oxalates, sulfites, chromates, oxides, silicates, and phosphates are insoluble. 8. Except for rule 1 and 2, Sulfides are insoluble except for calcium, barium, strontium, magnesium.

Which of the following are soluble in water? a. Sr. SO 4 Not soluble b. Na. NO 3 soluble c. Pb. Cl 2 Not soluble

Precipitation Reactions When a solid doesn’t dissolve it is called insoluble. A solid that forms when two solutions are mixed is called a precipitate. Remember!!! State of matter is shown as a subscript in parentheses after the element or compound Solid (s) Aqueous/dissolved Gas (g) (aq)

Predict the products of the following reaction: (if no solid precipitate is formed, there is no reaction) Pb(NO 3)2(aq) + KI (aq) Pb(NO 3)2(aq) + 2 KI (aq) Pb. I 2(s) + 2 KNO 3 (aq) We know it is a solid precipitate because it is insoluble according to the solubility rules.

A picture of the reaction: Pb 2+ NO 3 K+ NO 3 - K+ I- NO 3 K+ Pb. I 2(s) Because and NO 3 remain dissolved, they are called spectator ions and are not included in the net ionic equation. Net Ionic Equation Pb 2+ (aq) + 2 I-(aq) Pb. I 2(s) -

Net Ionic Equation Write the balanced chemical and net ionic equation for: Na 2 CO 3(aq) + Ca. Cl 2(aq) Step 1: Write the balanced chemical equation Na 2 CO 3(aq) + Ca. Cl 2(aq) Ca. CO 3(s) + 2 Na. Cl (aq) Insoluble precipitate Step 2: Remove the spectator ions (those that are soluble). Ca 2+(aq) + CO 32 -(aq) Ca. CO 3(s)