1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
monitta
3 years ago
14

You decided to prepare a phosphate buffer from solid sodium dihydrogen phosphate (NaH2PO4) and disodium hydrogen phosphate (Na2H

PO4)and you need 1L of the buffer at pH 7.00 with a total phosphate concentration(NaH2PO4+ Na2HPO4) of 0.100 M. Hint:Phosphoric acid (H3PO4), a triprotic acid, has 3 pKa values: 2.14, 6.86, and12.4. Determine the weight in grams of sodium dihydrogen phosphate (NaH2PO4;138g/mol) and disodium hydrogen phosphate (Na2HPO4;142g/mol) needed to prepare this buffer.
Chemistry
1 answer:
KIM [24]3 years ago
7 0

Answer:

For disodium hydrogen phosphate:

5.32g Na2HPO4

For sodium dihydrogen phosphate:

7.65g Na2HPO4

Explanation:

First, you have to put all the data from the problem that you going to use:

-NaH2PO4 (weak acid)

-Na2HPO4 (a weak base)

-Volume = 1L

-Buffer pH = 7.00

-Concentration of [NaH2PO4 + Na2HPO4] = 0.100 M

What we need to find the pKa of the weak acid, in this case NaH2PO4, for that you need to find the Ka (acid constant) of NaH2PO4, and for this we use the pKa of the phosphoric acid as follow:

H3PO4 = H2PO4 + H+    pKa1 = 2.14

H2PO4 = HPO4 + H+       pKa2 = 6.86

HPO4 = PO4 + H+      pKa3 = 12.4

So, for the preparation of buffer, you need to use the pKa that is near to the value of the pH that you want, so the choice will be:

pKa2= 6.86

Now we going to use the Henderson Hasselbalch equation for the pH of a buffer solution:

pH = pKa2 + log [(NaH2PO4)/(Na2HPO4)]

The solution of the problem is attached to this answer.

Download odt
You might be interested in
I need the answer to 452 of arogon
yaroslaw [1]
I'm confused... is there more info? 
3 0
3 years ago
Covalent bonds form between hydrogen and oxygen atoms in a water molecule as a result of the:________.
Oliga [24]

Answer:

D

Explanation:

A covalent bond is said to be formed when two electrons are shared between two bonding atoms as in the formation of the water molecule.

5 0
3 years ago
In a two-step synthesis, C6H11Br is converted into C6H12O. From the structure of the product, molecular formula of the starting
tamaranim1 [39]

Answer:

See explanation below

Explanation:

The question is incomplete. However in picture 1, you have the starting materials and the structure of the product, which you miss in this part.

Now, in picture 2, you have the starting reactant and the product, and the mechanism that is taking place here.

First, all what we have here is an acid  base reaction. In the first step, we are using the acid medium to convert the reactant into an alcohol. The bromine there, is not leaving the molecule yet, because it's neccesary for the next step. The starting reactant is an alkene, in that way, we can convert the reactant in the first step into a secondary alcohol. In other words, the first reaction is a alkene hydration.

In the second step, we use a strong base. You may say this is a strong nucleophile and will do a Sn2 reaction to form another alcohol there, but it's not the case, because, before any kind of reaction happens, the priority here is always the acid base, so the base will react with the acidic hydrogen. In this case, it will substract an hydrogen from the OH. When this happens, the lone pair will do an auto condensation here, and attacks the bromine in the molecule. In this way, the molecule will become a cyclomolecule, and that way it form the final product.

See picture 2, for mechanism

8 0
3 years ago
In an experiment, mice were fed glucose (C₆H₁₂O₆) containing a small amount of radioactive carbon. The mice were closely monitor
Luden [163]
<h3>Answer:</h3>

Carbon dioxide

Explanation:

  • Cellular respiration involves a break down of sugars such as glucose to yield energy in the form of ATP and water together with carbon dioxide as byproducts.
  • In this case, when mice are fed with glucose, cellular respiration takes place breaking down glucose to yield energy in the form of ATP, water and carbon dioxide.
  • Therefore, the radioactive carbon in glucose showed up in carbon dioxide, since the carbon in glucose ends up in carbon dioxide.
8 0
3 years ago
Can someone help me fill in the rest of the that don't have any words on top of the pictures. Please label the number then the w
QveST [7]
Tweezers 3 okay got it good
3 0
3 years ago
Other questions:
  • Calculate the percent dissociation of trimethylacetic acid(C6H5CO2H) in a aqueous solution of the stuff.
    15·1 answer
  • A mass of the crucible (g) 88.000g
    9·1 answer
  • What are the products of burning fuel
    12·1 answer
  • Glass is an example of a(n) ________ solid
    5·2 answers
  • If a person looking at a poster sees green instead of yellow and doesn't see red at all, this person most likely has color blind
    5·2 answers
  • How can substitution mutation affect a person’s traits?
    11·1 answer
  • Balance this chemical equation. A coefficient of "1" is understood. Choose option "blank" for the correct answer if the coeffici
    14·1 answer
  • Why do you think evolution is important?
    14·2 answers
  • Explain how you determine the freezing point of a solution that does not have a well-defined transition in the cooling curve.
    8·1 answer
  • For the reaction a 3b → 2c, the rate of disappearance of b given by (δ[b]/δt) may also be expressed as?
    13·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!