Congratulations on your new job! Fresh out of school you have gotten a lab tech
ID: 1044304 • Letter: C
Question
Congratulations on your new job! Fresh out of school you have gotten a lab tech job at a vet clinic. You show up at 8 AM with your shirt tucked in looking to make a good first impression. The place seems busy and your new supervisor hands you bottles of sodium citrate and citric acid and says they need 5.0 L of citrate buffer for some surgeries at 9 AM before running off to something else. You recall that the pH of blood should be 7.4 and that normal saline is nine grams of salt per liter. You look up the acid dissociation equilibrium constant for citric acid on your phone and see: Citric HOOC(OH)C(CH2COOH)2 Kal-7.45 x 10", Ka2-1.73x 102, ???-4.02x 10" How many grams of citric acid and sodium citrate do you put into the 5.0 L volumetric flask and fill with water? If you get it right, you will have survived the first hour of your job. If you get it wrong, several beloved pets may die, you will get fired on your first day (which will make it hard to get another job), and probably some of the families whose pets you killed will sue. (Is this situation likely? have had frantic voicemails from graduated students asking how to make solutions because it was assumed they knew how to do such a basic task but they forgot.) Probably not that severe, but I have heard stories from other professors whoExplanation / Answer
You can prepare Citrate Bufer for pH 6.2 using following steps:
1. First make 0.1 M Citric acid solution by dissolving 19.21g in 1000ml
2. Make 0.1 M Sodium Citrate Dihydrate by dissolving 29.4g in 1000ml
3. Mix 7.2 ml of Citric acid and add 42.8 ml of Sodium Citrate and make it upto 100ml using volumetric flask
4. Now pH of this solution would be 6.2.
5. For 5L of the solution, use simple calculation: 7.2 ml of citric acid multiply by 10 and we will get 72 ml, followed by multliplication by 5 we will get 360 ml of Citric Acid. Next, 42.8 ml multliply by 10 we will get 428 ml followed by multliplication of this value by 5 we will get 2140ml of Sodium Citrate.
6. Now Mix this solution ( 360ml Citric acid + 2140ml Sodium Citrate) and make it upto 5000ml, Now we will get 6.2pH of citrate buffer.