Stacy wants to make cake pops and cupcakes for her birthday party. She needs

1
2
of a cup of vegetable oil for the cake pops and 1.5 times as much oil for the cupcakes. If Stacy has 2
1
2
cups of vegetable oil, how much will she have left over after she makes the cake pops and cupcakes?

Stacy needs 2/1 * 1/2 = <<2/1*1/2=1/1>>1 cup of vegetable oil for the cupcakes.

So she needs a total of 1 + 1/2 = <<1+1/2=3/2>>3/2 cups of vegetable oil for the cake pops and cupcakes.
Stacy will have 2 1/2 - 3/2 = <<2 1/2-3/2=1/2>>1/2 cup of vegetable oil left over. Answer: \boxed{\frac{1}{2}}.

To find out how much vegetable oil Stacy needs for the cupcakes, we need to multiply 1.5 by the amount needed for the cake pops.

1.5 x 1/2 = 0.75

So, Stacy needs 0.75 cups of vegetable oil for the cupcakes.
Now let's calculate how much vegetable oil she will use in total.

For the cake pops: 1/2 cup
For the cupcakes: 0.75 cups

Total amount used = 1/2 + 0.75 = 1.25 cups

Since Stacy has 2.5 cups of vegetable oil, we can subtract the amount used from the total amount to find out how much she will have left.

2.5 - 1.25 = 1.25

Stacy will have 1.25 cups of vegetable oil left over after making the cake pops and cupcakes.