Logo
Home Study Material Contact Search
AI Chat FREE
  1. sciences
  2. chemistry
  3. buffer preparation is a necessary part of working

Buffer preparation is a necessary part of working with any living cell culture. Buffers are most...

Free

50.1K

Verified Solution

Question

Chemistry

Buffer preparation is a necessary part of working with anyliving cell culture. Buffers are most commonly prepared by startingwith a weak acid, HA, or weak base, A-, and adding enough strongacid, H+, or strong base, OH-, to find the correct ratio of[HA]/[A-]. A pH = 7.3 buffer is needed in the lab. This buffer ismade by first dissolving 52.25 g K2HPO4 in 400 mL of water. What isthe pH of this salt solution? This solution of course will be toobasic becuase we only have the base of the buffer present. Whatmust the value of the ratio of [H2PO4-]/[HPO42-] be to create abuffer solution that is pH = 7.3? How many moles of HCl must beadded to the 400 mL solution of HPO42-(aq) to prepare the pH = 7.3buffer solution? How many mL of 1 M HCl must be added to thesolution to create the pH = 7.3 buffer solution?

Answer & Explanation Solved by verified expert
3.9 Ratings (609 Votes)

a)

moles of K2HPO4- = 52.25 / 174.17 = 0.3

concentration of HPO42- = 0.3 x 400 / 1000 = 0.12 M

HPO42- + H2O   ----------------> H2PO4- + OH-

0.12                                                   0             0

0.12 - x                                               x             x

Kb2 = x^2 / 0.12 - x

1 x 10^-14 / 6.2×10–8 = x^2 / 0.12 - x

x = 1.39 x 10^-4

[OH-] = 1.39 x 10^-4 M

pOH = -log [OH-] = -log(1.39 x 10^-4)

         = 3.86

pH = 10.14

pH = pKa2 + log [salt / acid]

7.3 = 7.21 + log [HPO42-]/[H2PO4-]

[HPO42-]/[H2PO4-] = 1.23

[H2PO4-]/[HPO42-] = 0.813
Get Answers to Unlimited Questions

Join us to gain access to millions of questions and expert answers. Enjoy exclusive benefits tailored just for you!

Membership Benefits:
  • Unlimited Question Access with detailed Answers
  • Zin AI - 3 Million Words
  • 10 Dall-E 3 Images
  • 20 Plot Generations
  • Conversation with Dialogue Memory
  • No Ads, Ever!
  • Access to Our Best AI Platform: Flex AI - Your personal assistant for all your inquiries!
Become a Member

Other questions asked by students

Q

P Company S Corporation Revenues $(700,000) $(400,000) Expenses 400,000 300,000 Investment Income Not given -0- Dividends declared 80,000 60,000 Retained Earnings, 1/1/18 (600,000) (200,000) Current Assets 400,000 500,000 Equipment 700,000 300,000 Copyrights 900,000 405,000 Royalty Agreements 600,000 1,000,000 Investment in S Not given -0- Liabilities (500,000) (1,380,000) Common Stock (600,000) ($20...

Accounting
Q

What is the gain material and its phase, typical pumping method, typical output power, and efficiency...

Physics
Q

Vector operators

Advance Math
Q

Budgeted overhead cost $1,050,000 Estimated machine hours 50,000 Estimated direct labor hours 10,000 Estimated direct materials cost $1,500,000 Maverick’s inventory count, completed on...

Accounting
Q

Bacteria with sex pili can reproduce which differs from the typical binary fission process of...

Biology
Q

Why is James Meredith a significant civil rights figure O He won a federal court...

Biology
Q

You have two coaxial cylindrical conducting shells one with radius a and the second radius...

Physics
Q

Verify which of the following are trigonometric identities.1) 1 + cos ? / [cot? (1-sin?)]=...

Basic Math
Q

describe the internal role of accounting for organizations?

Accounting
Q

please need answer now Certain budget reports are prepared monthly, whereas others are prepared more...

Accounting
Q

In year 0, Longworth Partnership purchased a machine for $57,250 to use in its business....

Accounting
Q

Question 25 7 pts Each spring, Matt and Sue release forecasts for the price of...

Finance