A client is to recieve 2.00g of a drug. The drug comes on a solution that has 500 mg per 5.0 mL. Each vial contains 10 milliliters. How many vials do you need?

2 vials

Explanation:

The concentration (C) of the drug in the solution is:

C= 500 mg/5 mL = 100 mg/mL

Each vial with a volume (V) of 10 mL, contains the following mass of drug:

V= 10 mL ⇒ C x V = 100 mg/mL x 10 mL = 1000 mg

As you need 2.00 g, and 1 gram is equivalent to 1000 mg, the mass needed is 2.00 g x 1000 mg/1 g = 2000 mg

Thus, you have to divide the mass you need into the mass of each vial:

(2000 mg)/(1000 mg/vial) = 2 vials

Therefore, you need 2 vials.