4. Using the bicarbonate buffer system as an example, explain how buffers work

6. From the titration curve at the right, determine a. If the acids/bases are strong or weak b. Whether the acid or base was added from the buret c. The volume required to reach the equivalence 13 11 9 pH 7 5 3 1 5 10 15 20 d. The pH of the equivalence point e. The region where buffering occurs f. The volume and pH at the half equivalence point g. The K of the base used Volume added (mL) 25 25 h. The region where the [B]: [BH+] ratio is greater than 1 i. The region where the [B]: [BH+] ratio is less than 1 j. The concentration of acid if the titration started with 50.0 mL of 0.050 M base. k. Suggest a good indicator to use for this titration and explain why.

9. Find the final concentration as a percent (w/v) of dextrose when 75 mL dextrose 50 % (w/v), 50 mL of sodium chloride 0.9 % (w/v), and 100 mL of dextrose 5 % (w/v) sodium chloride 0.45 % (w/v) solution are mixed together.

Buffer systems can absorb hydrogen ions from the blood to increase pH into homeostatic range (pH: 7.35 to 7.45)During what condition would buffer systems do this?

II. Lipids from an organic sample are extracted separately by column chromatography using the ff eluants: 1st eluant - chloroform: methanol: water (6:3:1) 2nd eluant - methanol: chloroform (9:1)3rd eluant – petroleum ether: ethyl ether (1:1) Test results for each eluate are tabulated below. Identify the possible lipid present in each eluate. Based on the results above, _________________ 1. _________________ 2. _________________ 3. _________________ 4. _________________ 5. answer the following questions: What visible positive result for test reagent no. 5?Give the name of chemical characterization test for test reagent no. 3?What class of lipids will give a visible positive result on the test mentioned in question no. 2?Give the chemical name of the product formed after giving a positive result for test reagent no. 1?Test reagent no. 1 is used to test for what organic compound?