Please show work that is needed 14. What is the predominate species for the H2PO
ID: 1016435 • Letter: P
Question
Please show work that is needed
14. What is the predominate species for the H2PO4 - /HPO4 2- buffer at a pH of 8.5? Ka = 6.2x10-8
A. H3PO4 B. H2PO2- C. H2PO4 - D. HPO4 2-
15. Acidic solutions will turn a plant pigment molecule (blue litmus) from blue to __________.
A. green B. yellow C. black D. red 16. The hydrocarbon part “R” in butanoic acid is a ___________ group. A. butyl B. propyl C. ethyl D. methyl
17. What is the condensed structure for heptanoic acid?
A. CH3CH2CHCHCH2CH2COOH B. CH3CH2CH2CH2CH2CH2CH2COOH C. CH3CH2CH2CH2CH2CH2COOH D. CH3CH2CH2CH2CCCOOH
20. What is the name of the base form (carboxylate ion) for 4- methylhexanoic acid?
A. methylhexanide ion B. ethyl-4-hexanoic ion C. 4-methylhexanoate ion D. methyl-4-heximate ion
Explanation / Answer
14] D
pH = pKa + log [Base] /[acid]
8.5 = 7.2 = log [HPO4-2] / [H2PO4-]
[HPO4-2] / [H2PO4-] = 16.98
so concentration of D is higher
15] red
16] propyl
17] CH3CH2CH2CH2CH2CH2COOH
18] 4-methylhexanoate ion