Question

A 1.00 liter solution contains 0.40 M ammonia and 0.52 M ammonium perchlorate. If 0.130 moles of barium hydroxide are added to this system, indicate whether the following statements are true or false. (Assume that the volume does not change upon the addition of barium hydroxide.) A. The number of moles of NH3 will decrease. B. The number of moles of NH4 will decrease. C. The equilibrium concentration of H3O will remain the same. D. The pH will decrease. E. The ratio of [NH3] / [NH4 ] will decrease.

Answer 1

Answer:

A) False

B) True

C) False

D) False

E)False

Explanation:

Step 1: Data given

Volume = 1.00 L

Molarity of ammonia (NH3) = 0.40 M

Molarity of ammonium perchlorate (NH4ClO4) = 0.52 M

Number of barium hydroxide (Ba(OH)2 added = 0.130 moles

Step 2:

NH3 and NH4+ will form a buffer together. Here is NH3 a weak base and NH4+ its conjugate acid.

When we add barium hydroxide (Ba(OH)2 , this is a strong base, the hydroxide ions (OH-) will react with acid ( NH4+).

This makes that the amount of NH4+ ions will reduce and the concentration of the base (NH3) will increase.

Step 3: The equation

NH4+ + OH- ⇆ NH3 + H2O

Step 4: The statements

A. The number of moles of NH3 will decrease.

 ⇒ False, the number of moles will increase

B. The number of moles of NH4 will decrease.

  ⇒ TRUE

C. The equilibrium concentration of H3O will remain the same.

⇒ False, concentration of H3O will decrease

D. The pH will decrease.

⇒ false, It will slightly increase

E. The ratio of [NH3] / [NH4 ] will decrease.

⇒ false, since the amount of NH3 will increase and the amount of NH4+ will decrease. The ratio will increas