How to calculate the fractional compositions

Reference no: EM13293684

1 "HEPES" is an abbreviation for N-2-hydroxyethylpiperazine-N?-2-ethanesulfonic acid, a commonly used buffer in biochemistry. The structure and pKa of HEPES are given in Table 8-2 of Harris. Note that the form shown in the table is actually a zwitterion, with a protonated 3° amine (ammonium) and a deprotonated sulfonic acid (sulfonate). But since sulfonic acids have very low pKa values (they are essentially "strong"), we will ignore the sulfonic acid proton and treat the zwitterion as a monoprotic acid, "HA."

a.Write the net ionic equation that occurs when some strong acid is added to a HEPES buffer. Include physical states.

b. Write the net ionic equation that occurs when some strong base is added to a HEPES buffer. Include physical states.

c. Calculate the fractional compositions ? 0 (HA) and ? 1 (A?) for HEPES at pH = 7.00, 7.56, and 7.80. Assume the ionic strength is zero. [Note: monoprotic fractional composition equations are explained on p. 28 of the Equation Guide.]

d. Consider a 0.100 M (total concentration) HEPES buffer at pH 7.80. Calculate the concentrations of HA and A?, then mmol of HA and A? in 50.0 mL of this buffer.

e. Calculate the pH that results when 1.00 mL of 1.00 M HCl is added to 50.0 mL of the buffer in part d. [Hint: how many mmol of H+ was added, and what does it this added H+ do?]

f. Calculate the pH that results when 1.00 mL of 1.00 M NaOH is added to 50.0 mL of the buffer in part d.

Reference no: EM13293684

Questions Cloud

What overhead rate will the company achieve : What overhead rate will the company achieve on the basis of this information? Use direct labor dollars as a base. Can anyone help me with this problem ? Thank you in advanced.

Find the amplitude of the subsequent simple harmonic motion : A 7.05 bullet traveling at 520 m/s embeds itself in a 1.85kg wooden block at rest on a frictionless surface. Find the amplitude of the subsequent simple harmonic motion

What is the resistance at100 degree centigrade : The resistance of a copper wire at 30oCis 50Ω. if the temperature coefficient of copperat 0oC is 0.00427, what is the resistance at100oC

For how many years will the money earn interest : If Aunt Tillie also wants to reward you with a graduation gift of cash and she deposits $1,000 in an account at the end of each year for the next four years, for how many years will the money earn interest.

How to calculate the fractional compositions : Calculate the fractional compositions 0 (HA) and 1 (A) for HEPES at pH = 7.00, 7.56, and 7.80. Assume the ionic strength is zero.

What is the electric field strength at the given points : An electric dipole is formed from 1.0nC charges spaced 3.00 mm apart. What is the electric field strength at the given points

How much total interest is paid over the life of the loan : Prepare an amortization schedule for a five-year loan of $50,000. The interest rate is 8 percent per year, and the loan calls for equal annual payments. How much interest is paid in the third year? How much total interest is paid over the life of ..

Create a mask set and process flow that will produce a wheel : Using combination of deposited oxide and polysilicon films, create a mask set and process flow that will produce a wheel that can rotate freely about a hub that extends over the top of the wheel.

How much will the company earnings per share be diluted : Based on that information, what long-run growth rate can the firm be expected to maintain? (Hint: g = Retention rate x ROE.)

User Account

All Pages