Homework question

[Grace_Stevenson_1A]

Why in 18 is it named 2 but in 19 it's called secondary? (see photo below) thank you so much!!! Also why does the alcohol get priority over the two methyl groups? Thanks!

[Alex Chen 1B]

In 18, the 2 refers to the carbon that the alcohol is attached to, which is the second carbon in the three-carbon chain. In 19, the alcohol is named in the same way with the 2-hexanol, which tells you that the alcohol is attached to the second carbon in the six-carbon chain. The fact that that's a secondary alcohol refers to the fact that the carbon attached to the hydroxyl group is attached to two other carbons. So you can have a primary alcohol if the carbon is only attached to one other carbon and a tertiary alcohol if the carbon is attached to three other carbons. The alcohol gets priority over the two methyl groups because functional groups always get the highest priority.