Obtain 350 ml of the 0050 m phosphate buffer ph 65 in a...

Obtain 35.0 mL of the 0.050 M phosphate buffer (pH = 6.5) in a clean beaker. Add 0.20 M standard NaOH solution dropwise using a buret until the pH changes by 1 unit. Repeat the procedure using 0.0050 M phosphate buffer (pH= 6.5). Based on the parameters, calculate the buffer capacity of 0.050 M phosphate buffer and 0.0050 M phosphate buffer. Parameters 0.050 M phosphate buffer 0.0050 M Phosphate buffer Volume of phosphate buffer, mL 35.0 35.0 change in pH 1.0 1.0 change in V NaOH, L 0.0059 0.0006 How does the concentration of the buffer affect the buffer capacity?

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Transcript

00:01 In this question, we're asked about the buffer capacity and we are asked about the relationship of how the concentration of the buffer affects the buffer capacity.

00:13 So we need to know what buffer capacity is.

00:18 So we can calculate buffer capacity by using this formula, which is number of moles of acid or base which is used to change the ph divided by the change in ph.

00:39 Multiplied by the volume of buffer.

00:44 And remember that this volume has to be in liters.

00:49 So using this, let's look at the first part where they gave us 35 ml of 0 .05 molar buffer.

00:59 So we will be using m1 v1 is equal to m2 v2 in order to find the volume of the naoh which is used.

01:11 So we know m1 is nothing but 0 .05 multiplied by 35 ml.

01:18 That is equal to we use 0 .2 molar of this nao h for titration.

01:26 And we're finding v2.

01:28 Here we'll get volume is equal to 8 .75 milliliters.

01:35 And we know that molarity is nothing but number of moles.

01:44 Divided by the volume of solution.

01:48 And we know that m is nothing but 0 .2.

01:52 This is equal to we need to find the number of moles because in the formula this is the number of moles of acid or base.