Question

2.50 g of an unknown base is dissolved in 289 mL of water and has a concentration of 0.216 M. What is the identification of the unknown base?A. NaOHB. LiOHC. KOH

Answer 1

Answer:

The answer to your question is: A. NaOH

Explanation:

Data

mass = 2.5g of unknown base

volume = 289 ml = 0.289 l

concentration = 0.216 M

What is the base= ?

Formula

 Molarity (M) = # moles / Volumen (V)

 # moles = M x V

Process

# moles = 0.216 x 0.289 = 0.062     in the solution

MW NaOH = 23 + 16 + 1 = 40 g

MW LiOH = 7 + 16 + 1 = 24 g

MW KOH = 39 + 16 + 1 = 56 g

Rule of three

                        40 g of NaOH ------------------- 1 mol

                        2.5 g               --------------------  x

                 x = 2.5 x 1 /40 = 0.062 moles  is the same amount of moles in the

                                                                    solution is the answer

                         24 g of LiOH ----------------- 1 mol

                         2.5 g         ---------------------   x

                x = 2.5 x 1 / 24 = 0.104 moles

                      56 g of KOH ------------------ 1 mol

                      2.5 g             --------------------  x

                x = 2.5 x 1 / 56 = 0.045