A Chemist's Dilemma
Chemistry
Level
1
Statement I:
"You can have a pH less than 0"
Statement II:
"You can have a pH greater than 14"
Neither statement is correct
Statement II is correct but I is not
Statement I is correct but II is not
Both statement I and II are correct
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1 solution
Recall that pH = − lo g 1 0 ( [ H + ] ) , so if [ H + ] > 1 , then pH < 0 . Similarly, if [ H + ] < 1 0 − 1 4 , then pH > 1 4 . All of this is possible so long as [ H + ] ⋅ [ O H − ] = K W = 1 0 − 1 4 . The typical 0 to 1 4 scale for pH is used due to the equilibrium constant of water is 1 0 − 1 4 , and most solutions we deal with fall within that range.