No but it does need carbon dioxide and oxygen, be sure that
IMMEDIATELY after you drop the mentos in, you put your mouth over
the bottle opening and blow.
You get a 2 litres of coke (Diet Coke works the best) and leave
the cap off in an large, open area and put three~four of mentos
(mint ones are better than fruit flavoured ones) in and then it
will make a coke geyser.