# Properties of Acids and Bases

## Key Questions

• You are studying acids and bases??

Bases have a high pH (above 7).
They feel slippery.
They form hydroxide ions when placed in solution (they may do this by releasing a hydroxide ion or by causing them to be formed)
Bases are caustic (harmful to human skin)
They taste bitter.
Bases turn litmus paper blue and phenolphthlein pink.

Hope this answer gets you started and helps.

• #### Answer:

Acids lower the pH and bases increase the pH

#### Explanation:

pH is a measure of the acid concentration.
( measured in negative logs. )

At pH 7 the hydrogen ion concentration ( acid)  {H^+ or H_3O^+}
equals the hydroxide ion concentration ( base) {$O {H}^{-} 1$}

Acids have Hydrogen ion concentrations of 1 (100%) to just less than ${10}^{-} 7$
This is pH 0-6.9 Adding more acid increases the Hydrogen ion concentration lowering the pH.

Bases have Hydrogen ion concentrations greater than 10^-7 to ${10}^{-} 14$ ( ${10}^{-} 14$ = 100% hydroxide ion concentration)

This is pH 7.1-14 Adding more base increases the hydroxide ion concentration and lowers the hydrogen ion concentration.

See below :

#### Explanation:

1) They are sour in taste.
2) They can be corrosive
3) They turn blue litimus paper into red, yellow methyl orange into red and phenolpthalein into colorless