Understanding the Units:

* ml stands for milliliters, a unit of volume.

* L stands for liters. There are 1000 ml in 1 L.

Conversion:

1. Divide by 1000: 3500 ml / 1000 ml/L = 3.5 L

2. Express as a fraction: 3.5 L can be written as the mixed number 3 1/2 L.

Therefore, 3500 ml is equal to 3 1/2 L.