Unit 7 - Acids, bases and salts Flashcards
Properties of acids
- Contain H^+ ions
- Soluble in water
- Sour to the taste
- Corrosive
Properties of bases
- Found as metal oxides (O^2-), metal carbonates (CO3^2-), metal hydroxides (OH^-) or ammonia
- Some are soluble in water - called alkalis and are metal hydroxides
- Soapy to the touch
- Corrosive
Indicator
A chemical substance that changes color with changing H^+ concentration
Types of indicators
- Litmus
- Methyl orange
- Universal indicator paper
- Thymolphthalein
Litmus colors for acids and bases
- Acid = Red
- Base = Blue
Methyl orange colors for acids and bases
- Acid = Red
- Base = Yellow
Universal indicator paper colors for acids and bases
- Strong acid = Red
- Weak acid = Orange/Yellow
- Strong base = Purple
- Weak base = Blue
Thymolphthalein colors for acids and bases
- Acid = colorless
- Base = Blue
pH scale values
- 0-6 = Acid
- 7 = Neutral
- 8-14 = Alkaline (base)
Equation for an acid and metal reacting together
Acid + Metal –> Salt + Hydrogen
Equation for an acid and base reacting together
Acid + Base –> Salt + Water
Equation for an acid and metal carbonate reacting together
Acid + Metal carbonate –> Salt + Carbon dioxide + Water
Equation for an acid and ammonia reacting together
Acid + Ammonia –> Salt
Products of ammonium salts reacting with metal hydroxides
- Ammonia
- Salt
- Water
Brønsted-Lowry theory of acids and bases
- Acid is capable of donating a proton
- Base accepts a proton
- Water is amphoteric - can act as both acid and base
- Strong acids and bases ionize completely in water
- Weak acids and bases only partially ionize in water
- The conjugate base of an acid is formed after the acid donates the proton
- The conjugate acid of a base is formed after the base accepts a proton
- The two species in a conjugate acid-base pair have the same molecular formula except the acid has an extra proton compared to the conjugate base