<span>pH = pKa + log ([R-]/[RH])
Where pH is the pH of the buffer, [R-] is the concentration of the basic species, and [RH] is the concentration of the acidic species.
At pH 2.4, the amino group on glycine (pKa = 9.6) will be, for accounts and purposes, 100% protonated. This means our buffer will be dealing with the two ionic forms of the carboxyl group (pKa = 2.4).
When pH = pKa, the two species are in equilibrium. This can be seen using the HH equation:
2.4 = 2.4 + log ([R-]/[RH])
0 = log ([R-]/[RH])
1 = ([R-]/[RH])
[RH] = [R-]
Now we add in another equation, our conservation of mass.
M = [RH] + [R-]
where M is the molarity of the buffer
But since [RH] = [R-]:
M = 2 [RH]
0.2 = 2 [RH]
And we wind up with:
[RH] = [R-] = 0.1 M
Now to figure out the moles of each needed, we multiply by the volume of the buffer.
0.1 M * 0.1 L = 0.01 mol
This shows that to make 100 ml of 0.2 M glycine buffer, we'll need 0.01 mol of each species.
0.01 mol of 0.5 M HCl:
0.5 mol HCl / 1 L = 0.01 mol / v
solve for v
v/1 = 0.01 / 0.5 ==> v = 0.02 L or 20 mL
weight of glycine:
MW: 75.07 g/mol
0.01 mol glycine * (75.07g glycine / 1 mol) = 0.75 g glycine
And there's your answer
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To make this buffer you would add 0.75g glycine to 20 mL of 0.5 M HCl and fill with water until a 100mL volume was achieved.</span>
Answer:
b: a new formulation of paints
Explanation:
Answer:
a lagacy is amount of money or someones elses giving or left to someone in a will.
Answer: Option C
Explanation:
Maya believes that inchworms are faster when compared with snails. To prove this hypothesis she performs experiment and while performing experiment she ignored the inchworms that moves slower than snails.
This is a biased condition because she ignored the inchworms that were slow.
If she would have been unbiased then she should have tested all the inchworms that were slow or fast from snails.
Hence, option C is the correct answer.
