Acids and Bases And neutralization reactions

Acids and Bases An acid is a substance that produces hydrogen ions in solution. HCl  H + + Cl - A base is a substance that produces hydroxide ions in solution. NaOH  Na + + OH -

Acids Substances that release hydrogen ions (H+) when mixed in water Physical Properties: –Sour tasting –Wet to the touch when in solution –Water soluble –Good conductors of electricity, therefore electrolytes

Acids Chemical Properties –React with metals to produce hydrogen gas –Corrosive –Make chemical indicators change colour –React with bases to produce a neutral solution

Acids Examples:

Bases Substances that release hydroxide ions (OH-) when mixed in water. Also called alkaline Physical Properties: –Bitter tasting –Slippery to the touch when in solution –Water soluble –Good conductors of electricity, therefore electrolytes

Bases Chemical Properties –Corrosive –Make chemical indicators change colour –React with acids to produce a neutral solution

Bases Examples:

Chemical Indicators Are solutions that change colour in acids and in bases Can be either –natural or –synthetic

Chemical Indicators Litmus paper: –Base turns it Blue! –Acid turns it Red! Universal Indicator is a mixture of chemicals that changes colour through a wide range of pH values

The pH scale A numerical scale used to show how acidic or basic a solution is pH stands for “power of hydrogen”

The pH scale pH is a logarithmic scale which means that every unit on the scale represents a tenfold (10X) effect on the concentration of the solution

The pH scale: Logarithmic This means that pH 3 is 10 times more acidic than ph 4. If the value changes by more than one number you must multiply –ex. From pH 5 to pH 8 = 10 x 10 x 10 (3 steps = 10 multiplied by itself 3 times)

Naming Acids A binary acid forms when an H + bonds with a non-metal HF (aq), HCl (aq), HBr (aq), HI (aq), H 2 S (aq), and H 3 P (aq) are some common binary acids To name them, use the following structure: –“hydro + ______ ic acid”

Naming Acids An oxyacid has a non-metal and an oxygen component H 3 PO 4, HClO 3, HIO 3, H 2 SO 4, HBrO 3, H 2 CO 3, and HNO 3 are some common oxyacids To name them: –“_____________ ic acid”

Naming Bases 1.Name the metal 2.Name the polyatomic (i.e. hydroxide) Example –Mg(OH) 2 –magnesium hydroxide

Neutralization Reactions A type of double displacement reaction Acid + Base  Water + Salt A salt is an ionic compound. The pH of the products is around 7 (neutral) Example hydrochloric acid + sodium hydroxide  water + sodium chloride

Practise!! Try the practise questions on your worksheet!

Naming Acids and Their Ions There are two main kinds of acids: binary acids and oxoacids. A binary acid is composed of two elements: hydrogen and a non metal. The general formula for a binary acid is HX, where X is the non-metal. (HBr and HCl are two examples).

To name a binary acid Attach the prefix hydro Use the non-metal name as the root Attach the suffic “ic” Add the word acid

HF Hydrofluric acid HCl Hydrochloric acid HBr Hydrobromic acid HI Hydroiodic acid H 2 S Hydrosulfuric acid

An oxoacid (oxyacid) is an acid formed from a polyatomic ion that contains oxygen, hydrogen, and another element. For anions that end in “ate”, change the ending to “ic” and add the word acid ClO 3 - is chlorate HClO 3 - is called chloric acid

For anions that end in “ite”, change the ending to “ous” and add the word acid. ClO 2 - is chlorite HClO 2 - is chlorous acid

The prefixes hypo and per remain as part of the acid name. ClO 4 - is perchlorate HClO 4 - is perchloric acid