What is the ruling on using alcohol, and is it impure or not? And what is the ruling on vinegar made from alcohol, and to what extent can it be used in food?

Alcohol is an intoxicant, and every intoxicant is khamr (wine), and every khamr is forbidden (haram). Therefore, it is impermissible to eat food to which food vinegar mixed with alcohol has been added, unless the alcohol has transformed and lost its intoxicating quality before being mixed with the vinegar.