Lesson #2 Conjugate Acid and Bases Polyprotic Acids ACIDS BASES.
Acids and Bases
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Transcript of Acids and Bases
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), H2S (aq), and H3P (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
• H3PO4, HClO3, HIO3, H2SO4, HBrO3, H2CO3, and HNO3 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
• H2S
• 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
•ClO3- is chlorate
•HClO3- is called chloric acid
• For anions that end in “ite”, change the ending to “ous” and add the word acid.
• ClO2- is chlorite
• HClO2- is chlorous acid
• The prefixes hypo and per remain as part of the acid name.
• ClO4- is perchlorate
• HClO4- is perchloric acid