The answer is 'equal'. Hydroxide ions are OH- and Hydrogen ions are H+. Have you noticed they're opposite charges? Positive + negative = neutral. That's all there is to it :)
Most transition metal form more than one cation but aluminum forms the Al3+ cation only.
Pure chemistry: gain knowledge for own pleasure
Applied chemistry: gain knowledge to know how to use it
Yes, an OH group from ethanol can form a hydrogen bond to the ether O atom in the same way as it can do so with the single-bonded O atom in the ester.
The O atom in the carbonyl group of the ester can also form H-bonds with ethanol.
