Practice Worksheet for Test 1

[Lizette Noriega 1H]

Can anyone explain how they solved the following question (#7 from the UA Practice Exam Worksheet)? Thanks!

"A basic aqueous reaction initially had 0.057 M NH3. At equilibrium the concentration of hydroxides was 1.0x10^-3. Write out the equation and find the percent protonated."

[Brooke Yasuda 2J]

The equation would be NH3 + H2O --> NH4 + OH. It's given in the problem that 1E-3 Molar Hydroxide is present at equilibrium. Therefore, this must be the final equilibrium concentration of NH4 and OH because it is a 1:1 ratio. Percent deprotonation is the molar value of NH4+ formed at equilibrium divided by the initial concentration of the NH3. So, it is 1E-3 divided by .057 x 100.