You have the following buffer recipe and decide to make up...

You have the following buffer recipe and decide to make up some concentrated solutions first so that you won't have to weigh out dry ingredients, wait for them to dissolve, and correct the pH every time you make it. How much dry ingredients do you use for each of the following 4 stock solutions? Show you work and include units in your calculations. The Buffer Recipe is: 150 mM NaCl (formula weight 58.44 g) 10 mM Tris pH 8.0 (formula weight 121 g) 2 mM EDTA (formula weight 292 g) 0.2% bovine serum albumin -Stock 1 of 4: 3 M NaCl, 100 mL ________ ? -Stock 2 of 4: 1 M Tris, pH 8.0, 100 ml ________ ? -Stock 3 of 4: 0.5 M EDTA, 500 mL ________ ? -Stock 4 of 4: 10% bovine serum albumin, 10 mL ________ ?

Transcript

00:01 You have the following buffer recipe and decide to make up some concentrated solution first so that you won't have to wait out dry ingredients and wait for them to dissolve at the correct ph every time you make it.

00:13 So the question asks you about how much dry ingredient do you use for each of the following four stock solutions and show your calculations.

00:21 So the buffer recipe obviously has been shown.

00:35 So you have to have 0 .2 % borobudazetone albumin.

00:42 So the first stock solution is to make a 3 molar sodium chloride and with a volume of 100 milliliter.

00:56 So the first ingredient is stock one.

01:00 You want to make 3 molar sodium chloride with a volume of 100 milliliter.

01:17 So obviously you want to find out the dry ingredient you have to wait.

01:25 So very first thing you want to calculate a total mole of sodium chloride.

01:29 The mole of sodium chloride is going to be the concentration multiplied by the volume.

01:39 Concentration is 3 mole and the mole also can be converted into different unit mole per liter.

01:46 So they are the same thing interchangeable.

01:48 So 3 molar equals 3 mole per liter and the volume obviously is 100 milliliter.

01:56 We have a liter here milliliter here so you have to convert 100 milliliter to liter.

02:02 So we know that 1 mil is 0 .001 liter.

02:08 So obviously 100 is going to be times 100 here and times 100 there.

02:15 So this will give you 0 .1 liter.

02:18 So we use 0 .1 liter to replace 100 milliliter.

02:23 So 3 mole per liter times 0 .1 liter.

02:29 And liter and liter cancel out each other.

02:31 You end up having 0 .3 mole.

02:35 So this is the total mole in that 100 milliliter solution.

02:40 So if you want to calculate the mass which is the dry ingredient you want to weigh, this is the mass.

02:46 So the mass of sodium chloride is going to be the mole multiplied by the, we call it the formula weight or fw.

03:00 So 0 .3 mole multiplied by the formula weight of sodium chloride 58 .44 gram per mole.

03:13 So as you can see mole and mole cancel each other.

03:16 So you just have to do math.

03:18 This equals 17 .53 gram.

03:26 So this is the stock 1 that you have to weigh out.

03:32 Now let's move on to the second stock.

03:38 So according to the question you also want to make a stock 2 out of 4.

03:41 1 molar of tris ph 8 100 ml.

03:44 So we're going to use the same formula.

04:08 Mole of tris is going to be the concentration 1 mole per liter multiplied by the volume.

04:24 Again 100 milliliter we already know.

04:27 It equals 0 .1 liter.

04:29 And liter and liter cancel each other.

04:36 You have 0 .1 mole of tris.

04:42 Same thing you want to calculate the mass of tris.

04:46 This equals the mole which is, use the same formula right here.

04:54 0 .1 mole multiplied by the formula weight according to the question.

05:00 Tris formula weight is 121 gram per mole.

05:05 And mole and mole cancel out.

05:09 12 .1 gram of tris 3.

05:14 The third stock is 0 .5 molar of edta of 500 milliliter...

Question

Please give Ace some feedback