find two irrational numbers between 2.5 and 4.5

Answer 1

2.5 = 5/2
4.5 = 9/2

so, a short list of rational numbers between the two might contain

6/2 7/2 8/2

Expressing them as 6ths,
2.5 = 15/6
4.5 = 27/6
Now there are a lot more possibilities, all multiples of 1/6

Answer 2

Oops! I missed the "irrational" part!

Since
2.5^2 = 6.25
4.5^2 = 20.25

Pick any integers between those, except 9 and 16, which are perfect squares.

√7 √8 √10 ... √20
are all irrational.

Since
2.5^3 = 15.625
4.5^3 = 91.125

There are lots of possibilities there, excluding 27 and 64:

∛16 ∛17 ... ∛91
are all irrational

You can pick non-integer values, as long as they don't turn out to be perfect powers.