Question

1.) A student titrated 25.0mL of a buffer with 0.126 M HCL. What is the concentration of the weak base in the buffer? Document your logic(do not use M1V1=M2V2)

http://i1190.photobucket.com/albums/z451/chemistrypictures/chart1.jpg

2.) The student then titrated 25.0 mL of the same buffer with 0.115M NaOH. The observed titration curve is shown below. What is the concentration of the weak acid in the buffer?

http://s1190.photobucket.com/user/chemistrypictures/media/graph1.jpg.html

3.) What is the buffer strength?

4.) If the pH of the buffe (before it is titrated) is 5.70 what is the pKa of the weak acid. Hitn solve the Henderson-Hasselbalch equation for pKa

Answer 1

3.) What is the buffer strength?

it is refeered as a measure of the efficiency of of a support in opposing changes in pH. Ordinarily, the support limit and is communicated as the measure of solid corrosive or base, in gram-counterparts, that must be added to 1 liter of the answer for change its pH by one unit

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4.) If the pH of the buffe (before it is titrated) is 5.70 what is the pKa of the weak acid. Hitn solve the Henderson-Hasselbalch equation for pKa

for Buffer = the ratio =[A(-)]/[HA] = 1,

because this will give the highest buffer capacity, so

pH = pKa + log( [A(-)]/[HA] ) = pKa + log 1 = pKa + 0,

pH = pKa = 5.70. -answer

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