lecture 26

# lecture 26 - Turn on Camtasia Recording We have completed...

This preview shows page 1. Sign up to view the full content.

This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Turn on Camtasia Recording! We have completed chapter 17 and are moving on to chapter 18 18. ... 1 What is the common ion effect? A. The f t th t i i ti A Th fact that ionization of an acid or b f id base i is limited by the presence of it's conjugate base or acid. B. The principle that allows buffers to absorb acid or base without changing pH very much. C. C The interaction seen when HC3H5O3 and C C3H5O3- are in solution at the same time. D. A and C only E. All of the above ... 2 Citric acid has a Ka of 7.5 x 10-4. In what pH range is citric acid and its conjugate base a good buffer? A. pH 1.5-2.5 B. pH 2.5-3.5 C. pH 5.5-7.5 D. pH 7.5-8 E. pH 9-10 ... 3 Buffer Solutions Problem: What is the pH of a buffer that has [HOAc] = 0.700 M and [HOAc] [OAc-] = 0.600 M? HOAc + H2O OAc- + H3O+ Ka = 1.8 x 10-5 [HOAc] HOAc] [OAc-] [H3O+] equilib 0.700 - x 0.600 + x x Assuming that x << 0.700 and 0.600, we have g , K a = 1.8 x 10 -5 = [H3O+ ](0.600) 0.700 [H3O+] = 2.1 x 10-5 and pH = 4.68 ... 4 Buffer Solutions Notice that the expression for calculating the H+ conc. of the buffer is ... 5 HendersonHenderson-Hasselbalch Equation [H3O + ] = [Acid] Ka [Conj. base] Take th T k the negative l of both sides of thi ti log f b th id f this equation pH = pK a - log [Acid] [Conj. base] pH = pK a + log [Conj. [Conj base] [Acid] The pH is determined largely by the pKa of the acid and then adjusted by the ratio of acid and conjugate base. ... 6 What do you think is in the purple solution? A.An Acid B.A Base C.A salt D.Sea D S water t E.Boiled cabbage ... 7 Cabbage Water pH indicator-- anthocyanin pH pH pH pH pH p pH 2 4 6 8 10 12 red purple violet blue Blue-green g greenish yellow y ... 8 Indicators for Acid-Base Titrations Acid- ... 9 Natural Indicators Red rose extract at different pH's and with Al3+ ions Rose extract In CH3OH Add Al3+ Add HCl Add NH3 Add NH3/NH4+ See pages 848849 ... 10 Titrations pH Titrant volume, mL ... 11 ... 12 ... 13 ... 14 ... 15 ...
View Full Document

{[ snackBarMessage ]}

Ask a homework question - tutors are online