Chemistry Part 6

Reactivity Series of Elements

The coinage metals are the ones with the lowest reactivity.  The reactivity series gives an idea as to which element is capable of displacing other elements in a displacement reaction. Here’s a mnemonic to help you learn the reactivity series:

Private Second Class Mac Zitl He Can Make Some Gun Powder

Private (potassium)
Second (Sodium)
*Class (Calcium)
M (Magnesium)
a (aluminum)
c (Carbon)
Z (Zinc)
i (iron)
t (Tin)
l (Lead)
He (Hydrogen)
Can (Copper)
Make (Mercury)
Some (Silver)
Gun (Gold)
Powder (Platinum)

Li, K, Ca, Na, Mg, Al, Zn, Cr, Fe, Cd, Ni, Sn, Pb, H2, Cu, Ag, Hg, Au

Evidence of a reaction

1. Precipitate: when you join 2 things and a solid forms.
2. Change in appearance of the surface of the material.
3. In there is a gas given off.
4. Color change.
5. Change in temperature.

Single Displacement

A + BC -> B + AC

2 Ag NO₃ (aq) + Ca (s) -> Ca(NO3)₂(aq) + 2Ag (s)

Zn(NO3)₂ (aq) + Cu (s) -> NO REACTION because Zn is more reactive than copper.  The more reactive metal ends up with a charge.

Double Displacement

AB + CD -> AD + CB

The most common reaction is precipitate in a double displacement reaction.  Two solutions that are soluble could become solid.  In an acid-base reaction one product is water because the acid has hydrogen ions (H+) and the base has OH- so H+ and OH- = H2O + “salt” + heat.

Solubility Rules

1. Soluble: Group 1 alkali metal compounds, acetates, nitrates and ammonium compounds are all soluble.

2. Soluble: Hydroxides of Group 1 alkali metals and NH₄⁺¹, Ca⁺², Sr⁺², and Ba⁺² are soluble.  All others are insoluble.

3. Soluble: Group 7 halogens/halides are soluble except for those containing Ag⁺¹, Pb⁺², and Hg₂⁺².

4. Soluble: Most sulfates (SO₄₎ are soluble, except for BaSO₄, SrSO₄, Ag₂SO₄, PbSO₄ and CaSO₄. In general, if it’s a sulfate and it’s not with one of those Ba, Sr, Ag, Ca, Pb, then it’s aqueous.

5. Insoluble: Most phospates, carbonates, chromates and sulfides are insoluble (except those of the alkali metals and ammonium).

Electrolytes

Examples of strong acids are hydrochloric acid (HCl), hydroiodic acid (HI), hydrobromic acid (HBr), perchloric acid (HClO₄), nitric acid (HNO₃) and sulfuric acid (H₂SO₄).

Examples of strong bases are are Group 1 Hydroxides and Group 2 Hydroxides (except Mg (OH)2)