Question

How many mL of a 0.193 M aqueous solution of ammonium bromide, , must be taken to obtain 8.42 grams of the salt?

Answer 1

Answer:

445 mL NH₄Br

Explanation:

(Step 1)

Convert grams ammonium bromide (NH₄Br) to moles using its molar mass.

Molar Mass (NH₄Br): 14.007 g/mol + 4(1.008 g/mol) + 79.904 g/mol

Molar Mass (NH₄Br): 97.943 g/mol

8.42 grams NH₄Br                1 mole
-----------------------------  x  ------------------------  =  0.0860 moles NH₄Br
                                         97.943 grams

(Step 2)

Calculate the volume of NH₄Br using the molarity equation. Then, convert liters (L) to milliliters (mL).

Molarity (M) = moles / volume (L)

0.193 M = 0.0860 moles / volume

(0.193 M) x volume = 0.0860 moles

volume = 0.445 L

1,000 mL = 1 L

0.445 L NH₄Br           1,000 mL
------------------------  x  ------------------  =  445 mL NH₄Br
                                        1 L