The concentration ratio of conjugate acid to conjugate base for a 20 mM solution at pH 7.0 of an amino acid is 20:1.

Required:
a. What is the pK of the side chain?
b. What amino acid might this be?

Answers

Answer 1

Answer:

a. 8.3= pKa of the aminoacid

b. Cysteine

Explanation:

The pH of an acid can be obtained using the H-H equation:

pH = pKa + log [A-] / [HA]

Where pH is the pH of the buffer = 7.0

pKa is the pka of the conjugate acid = ?

[A-] / [HA] is the ratio between conjugate base and conjugate acid. As the ratio of conjugate acid to conjugate base = 20:1, the [A-] / [HA] = 1/20

Replacing:

7 = pKa + log 1/20

7 = pKa - 1.30

7+1.30 = 8.3 = pKa of the aminoacid

The only aminoacid with a side chain with pKa = 8.3 is:

Cysteine. Allowing its identification.


Related Questions

what following oxide react with both acids and bases to form salts.​

Answers

Answer:

mainly metal oxide use to react with both acid and bases to form salts such as zinc, aluminum etc.

Ammonium phosphate is an important ingredient in many solid fertilizers. It can be made by reacting aqueous phosphoric acid with liquid ammonia. Calculate the moles of phosphoric acid needed to produce 1.80 mol of ammonium phosphate. Be sure your answer has a unit symbol, if necessary, and round it to the correct number of significant digits.

Answers

Answer:

Explanation:

The reaction is

H3Po4+3NH3\to→ (NH4)3PO4

Given,7.10g NH3=7.10g/molar mass of NH3

=7.10g/(17.031g/mol)

=0.416mol

From the reaction

3 mol ammonia reacted and produced 1 mole of ammoniam phosphate

So,One mole ammonia reacted and produced 1/ 3 mole ammonium phosphate.

And Also,0.416 mole ammonium reacted and produced (1/3)0.416=0.138 mole ammonium phosphate.

Hence 0.138mole=0.138mole*149.08 g/mole

               =20.573gm ammonium phosphate produced.

Hence 20.573g of ammonium phosphate is produced by the reaction of 7.10 g of ammonia.

Classify each cation as a weak acid or pH neutral (neither acidic nor basic).

a. Na+
b. Ni2+
c. NH4+

Answers

Answer:

a. Na+ is pH neutral

b. Ni2+ = weak acid

c. NH4+ = Weak acid

Explanation:

To know the nature of the cation we need to find the nature of its conjugate base.

If the conjugate base of the ion is a strong base, the ion is neutral.

If the conjugate base is a weak base, the ion is a weak acid:

a. Conjugate base Na+ = NaOH

Sodium hydroxide is a strong base:

Na+ is pH neutral

b. Conjugate base Ni²⁺: Ni(OH)2 is a weak base because is not completely soluble in water. That means:

Ni2+ = weak acid

c. Conjugate base NH4+: NH4OH. Weak base:

NH4+ = Weak acid

Certain ketones such as fructose can be oxidized by Benedict's reagent under basic conditions to form what type of compound

Answers

Answer:

Certain ketones such as fructose can be oxidized by Benedict's reagent under basic conditions to form what type of compound

Explanation:

Benedict's solution is a mixture of copper sulfate, anhydrous sodium carbonate, and sodium citrate.

In presence of mild reducing agents, Cu(II) ion in Benedict's solution becomes the Cu(I) ion.

Fructose has an alpha-hydroxy ketone group.

It undergoes tautomerism and forms alpha-hydroxy aldehyde which gives a positive test with Benedict's reagent.

During this test, aldehydes will be converted into carboxylic acids.

The reaction of fructose with Benedict's reagent is shown below:

Consider the following reaction at equilibrium. What effect will decreasing the temperature have on the system? DH=+890kJCO2(g)+2H2O(l)<--> CH4(g)+2O2(g)a) the equilibrium constant will increaseb) the reaction will shift to the left in the direction of the reactantsc) the reaction will shift to the right in the direction of the productsd) no effect will be observed

Answers

Answer:

Option B. The reaction will shift to the left in the direction of the reactants.

Explanation:

The equation for the reaction is given below:

CO₂ + 2H₂O <=> CH₄ + O₂

Enthalpy change (ΔH) = +890 KJ

The reaction illustrated by the equation is endothermic reaction since the enthalpy change (ΔH) is positive.

Increasing the temperature of an endothermic reaction will shift the equilibrium position to the right and decrease the temperature will shift the equilibrium position to the left.

Therefore, decreasing the temperature of the system illustrated by the equation above, will shift the reaction to the left in the direction of the reactants.

Thus, option B gives the right answer to the question.

Question 1
1 pts
How many mols of bromine are present in 35.7g of
Tin(IV) bromate?

Answers

Answer:

n = 0.0814 mol

Explanation:

Given mass, m = 35.7g

The molar mass of Tin(IV) bromate, M = 438.33 g/mol

We need to find the number of moles of bromine. We know that,

No. of moles = given mass/molar mass

So,

[tex]n=\dfrac{35.7}{438.33}\\\\n=0.0814\ mol[/tex]

So, there are 0.0814 moles of bromine in 35.7g of  Tin(IV) bromate.

Which of the following was NOT explained by Dalton's atomic theory?
ANSWER:
A. the Law of Multiple Proportions
B. the difference between elements and compounds
C.?the difference between isotopes of an element
D. the Law of Conservation of Mass

Answers

Answer:

A. the Law of Multiple Properties

Answer:

A. the law of multiple proportions

liquid junction potential arise due to?

Answers

Answer:

liquid junction potentials

when a cell contains a boundary between two electrolytic solutions of different composition or concentration, a liquid junction potential is developed due to the "diffusion of the various components at characteristic rates in the boundary zone."

#carryonlearning

17. The density of a population would influence which limiting factor?
O niche
O growth rate
O weather
O space

Answers

Answer:

The answer is growth rate

Explanation:

it will help you

A chemist determines by measurements that 0.0800 moles of bromine liquid participate in a chemical reaction. Calculate the mass of bromine liquid that participates. Round your answer to 3 significant digits.

Answers

Answer:

The mass of bromine liquid that participates in  a chemical reaction=12.8 g

Explanation:

We are given that

Total number of moles of bromine liquid participate in chemical reaction=0.0800 moles

We have to find the mass of bromine liquid that participates.

Atomic mass of Br=79.9 g

1  mole of bromine liquid=2 atomic mass of bromine (Br)

1 mole of bromine liquid ([tex]Br_2[/tex]) =[tex]2\times 79.9=159.8 g[/tex]

0.0800 moles of  bromine liquid=[tex]159.8\times 0.0800[/tex] g

0.0800 moles of  bromine liquid=12.784 g

0.0800 moles of  bromine liquid[tex]\approx 12.8[/tex] g

Hence, the mass of bromine liquid that participates in  a chemical reaction=12.8 g

Select the statement that best answers the following question What effect does the anion of an ionic compound have on the appearance of the solution?
a. The anion affects the intensity of the color more than the color of the solution.
b. The anion affects the color of the solution more than the intensity of the color.
c. The anion does not affect the color or color intensity of the solution.
d. The anion only affects the intensity of the color in a solution.

Answers

Answer:

b. The anion affects the color of the solution more than the intensity of the color.

Explanation:

An ionic compound is one that is made up of ions held together by electrostatic forces. The ions are made up of positively charged ions known as cations and negatively charged ions known as anions. In compounds with a high ionic attribute, anions produce colorless compounds. But compounds that have less ionic attributes produce deeper colors like black and red. When in solutions, ionic compounds take on color and this is because of the anion that absorbs infrared light energy.

6ooo kg into quintal​

Answers

Answer:

60 q

Explanation:

The conversion factor is 100; so 1 quintal = 100 kilograms. In other words, the value in q multiply by 100 to get a value in kg.

Rank the following substances/solutions in order of lowest boiling point to highest boiling point where 1 has the lowest boiling point and 5 has the highest boiling point. pure water; 1.0 m NaCl; 0.5 m KBr, 0.75 m CaCl2; 1.5 m glucose (C6H12O6)

Answers

Answer:

1) pure water

2) 0.75 m CaCl2

3) 1.0 m NaCl

4) 0.5 m KBr

5) 1.5 m glucose (C6H12O6)

Explanation:

Boiling point elevation is a colligative property. Coligative properties are properties that depend on the amount of solute present in the system. The boiling point of solvents increase due to the presence of solutes.

The boiling point elevation depends on the number of particles the solute forms in solution and the molality of the solute. The more the number of particles formed by the solute and the greater the molality of the solute, the greater the magnitude of boiling point elevation.

The order of decreasing hoping point elevation is;

1) 0.75 m CaCl2

2) 1.0 m NaCl

3) 0.5 m KBr

4) 1.5 m glucose (C6H12O6)

In an exothermic chemical reaction:____.
A. The mass of the products is greater than the mass of the reactants.
B. The mass of the products is less then the mass of the reactants.
C. Heat is released as the reaction proceeds.
D. Heat is absorbed as the reaction proceeds.

Answers

Answer:

C

Explanation:

Think of 'exo' as exit and 'thermic' as relating to thermal energy/ heat. Thus, an exothermic release thermal energy as the reaction proceeds.

In an exothermic reaction, the total energy of the products is lesser than that of the reactants and ΔH (change in energy) is less than zero.

When heat is absorbed as the reaction proceeds, the chemical reaction is an endothermic reaction.

How many grams of boiling water must be added to an insulated cup containing 19 grams of ice, at 0oC, to completely melt the ice

Answers

Answer:

1900grams of boiling water

Explanation:

0,c=19

100,c=19×100

1900grams

Where do reactions in a solid
generally take place?
A. All throughout the solid
B. At the center of the solid.
C. Only on opposite sides of the solid
due to repelling forces.
D. On the surface of the solid.

Answers

Answer:

A

Explanation:

because solid stick together like magnetic and can feel every vibration

Answer:D

Explanation: on the surface of a solid

What is the law of multiple proportions?
A. The proportion of elements to compounds is constant.
B. All elements are found in equal proportions in nature.
C. Different compounds may contain the same elements but may have different ratios of those elements.
D. All compounds contain the same elements in the same proportions.

Answers

A I think I may be wrong

The elemental mass percent composition of succinic acid is 40.68% CC, 5.12% HH, and 54.19% OO. Determine the empirical formula of succinic acid.

Answers

Answer:

C2H3O2

Explanation:

Empirical formula is defined as the simplest whole-number ratio of atoms present in a molecule. To solve this question we need to convert the percentage of each atom to moles using molar mass. With the moles of each atom we can find the ratio:

Moles C -Molar mass: 12.01g/mol-

40.68g * (1mol/12.01g) = 3.387 moles C

Moles H-Molar mass:1g/mol-:

5.12g * (1mol/1g) = 5.12 moles H

Moles O -Molar mass: 16g/mol-

54.19g * (1mol/16g) = 3.387 moles O

Ratio of atoms (Dividing in moles of C that are the lower number of moles):

C = 3.387 moles C / 3.387moles C = 1

H = 5.12moles H / 3.387moles C = 1.5

O = 3.387moles O / 3.387 moles C = 1

This ratio twice (To have only whole-numbers):

C = 2

H = 3

O = 2

Empirical formula of succinic acid:

C2H3O2

what mass of phenol must be dissolved in 25.0 g of naphthalene to produce a solution that is 0.22 m in phenol

Answers

Answer: A mass of 0.518 g of phenol must be dissolved in 25.0 g of naphthalene to produce a solution that is 0.22 m in phenol.

Explanation:

Given: Mass of naphthalene = 25.0 g

Molality = 0.22 m

This means that 0.22 moles of solute is present per kg of solvent.

As 25.0 g  of naphthalene is there that will be 25.0 g per 1000 g (1 kg) is equal to 0.025 kg.

Hence, moles of phenol are calculated as follows.

[tex]Molality = \frac{moles}{mass (in kg)}\\0.22 m = \frac{moles}{0.025 kg}\\moles = 0.0055 mol[/tex]

Also, molar mass of phenol is 94.11 g/mol. This means that 1 mole of phenol contains 94.11 g.

Therefore, mass contained by 0.0055 moles of phenol is as follows.

[tex]0.0055 mol \times 94.11 g/mol \\= 0.518 g[/tex]

Thus, we can conclude that a mass of 0.518 g of phenol must be dissolved in 25.0 g of naphthalene to produce a solution that is 0.22 m in phenol.

Complete and balance the equations for the given single displacement reactions. Write the reaction in molecular form. Phases are optional. If you need to clear your work and reset the equation, click the CLR button.Li(s) + H2O---------- Ca(s) + H2O ---------------

Answers

Answer:

Li(s) + H2O(l) -----> LiOH(aq) + H2(g)

Ca(s) + 2H2O(l) ---------------> Ca(OH)2(aq) + H2(g)

Explanation:

Metals react with water to yield the metal hydroxide and hydrogen gas as shown in the answer above.

The reaction equations were balanced, the number of atoms of each element on both side of the reaction equation is exactly the same.

This is the way to write a balanced reaction equation for the species shown in the question.

If mercury barometer is replaced by water barometer, height of water column

i. will be less than that of Hg Column
ii. will be greater than that of Hg column iii. will be equal to that of Hg column
iv. will be none of these​

Answers

Answer:

answer is first one 1 will be less then that of hg coloumn

22 Agas that is collected by upward delivery is likely to be A heavier than air B insoluble in water C lighter than air D Soluble in water

Answers

Answer:

joib

Explanation:

formula of
Al³⁺ and SO₄²⁻

Answers

Answer:

The formula of Al³⁺ and SO₄²⁻ is aluminum sulfate.

Explanation:

The formula for aluminum sulfate is Al₂(SO₄)₃. If we say in terms of ions. The ions are Al³⁺. It is a positive ion or the cation. Other ion is SO₄²⁻. It is sulfate ion. It is anion.

Aluminum sulphate is used in water purification and as a mordant in dyeing and printing textiles.

Hence, the formula of Al³⁺ and SO₄²⁻ is aluminum sulfate.

c. rubidium sulfate
2. Write balanced molecular equation, complete ionic equation, and net ionic
equations for the mixing of the following solutions. Show states. If no reaction
occurs, show the ionic equation. (8 marks)
a.
NaNO3 +
Ag2SO4 → AgNO3 + Na2SO4

Answers

I can do that which is B

which selection is an example of an electrolyte
a. potassium iodide in water
b. sucrose in water
c. pentane in octane
d. methanol in water

Answers

Answer:

i believe its A, potassium iodide in water

Explanation:

A. Potassium iodide in water

Which is the primary type of radiation from the sun that is absorbed by the ozone layer?
A. infrared radiatin
B. UV-B
C. X-rays
D. UV-C
E. UV-A

Answers

the answer to the question is B.UV-B

Zn-64 = 48.63%
Zn-66 = 27.90%
Zn-67 = 4.10%
Zn-68 = 18.75%
Zn-70 = .62%
Calculate the average atomic mass/given their percent abundance

Answers

Answer:

A = 65.46 u

Explanation:

Given that,

The composition of zinc is as follows :

Zn-64 = 48.63%

Zn-66 = 27.90%

Zn-67 = 4.10%

Zn-68 = 18.75%

Zn-70 = .62%

We need to find the  average atomic mass of the given element. It can be solved as follows :

[tex]A=\dfrac{48.63\times 64+27.90\times 66+4.1\times 67+18.75\times 68+0.62\times 70}{100}\\A=65.46\ u[/tex]

So, the average atomic mass of zinc is 65.46 u.

The table shows the nature of reactants and products formed in a certain type of chemical reaction.
Nature of Reactants and Products

Reactants

Metal + lonic compound

Products

Metal + lonic compound

Which of the following is true about the type of chemical reaction?

it is a single replacement reaction, and the anions in the two inic compounds are different.

It is a single replacement reaction, and the cations in the two ionic compounds are different.

It is a double replacement reaction, and the anions in the two ionic compounds are different.

It is a double replacement reaction, and the cations in the two ionic compounds are different.

Answers

Answer: It is true about the type of reaction that it is a single replacement reaction, and the cations in the two ionic compounds are different.

Explanation:

When one element in a compound is replaced by another element in a chemical reaction then it is called a single replacement reaction.

For example, [tex]K + NaCl \rightarrow KCl + Na[/tex]

Here, potassium metal is replacing the sodium metal in the sodium chloride compound.

As metals become cation by losing an electron in a chemical reaction.

Thus, we can conclude that it is true about the type of reaction that it is a single replacement reaction, and the cations in the two ionic compounds are different.

Answer: Its A

Explanation:

a single replacement reactions, and the ANIONS in the two ionic compounds are different

A 15.4 mL aliquot of 0.204 MH3PO4(aq) is to be titrated with 0.17 MNaOH(aq). What volume (mL) of base will it take to reach the equivalence point?

Answers

Answer:

55.44L of the 0.17M NaOH are required

Explanation:

Phosphoric acid, H3PO4, reacts with NaOH as follows:

H3PO4 + 3NaOH → Na3PO4 + 3H2O

Where 1 mole of H3PO4 reacts with 3 moles of NaOH

To solve this question we need to find the moles of H3PO4 in the aliquot. Using the balanced equation we can find the moles of NaOH and its volume with the concentration (0.17M) as follows:

Moles H3PO4:

15.4mL = 0.0154L * (0.204mol/L) = 0.00314 moles H3PO4

Moles NaOH:

0.00314 moles H3PO4 * (3mol NaOH / 1mol H3PO4) = 0.009425moles NaOH

Volume NaOH:

0.009425moles NaOH * (1L/0.17moles NaOH) = 0.05544L 0.17M NaOH =

55.44L of the 0.17M NaOH are required

What is the first step in the curved arrow mechanism for the chlorination of benzene in the presence of FeCl3

Answers

Answer:

See explanation

Explanation:

The chlorination of benzene occurs in the presence of a Lewis acid. A Lewis acid is a compound that can accept a lone pair of electrons.

The first step in the chlorination of benzene is the formation of the ion Cl^+ which attacks the benzene ring.

This ion is formed when the Cl2 molecule undergoes heterolytic fission assisted by FeCl3 to yield FeCl4^- and Cl^+.

The Cl^+ electrophile now attacks the benzene ring to yield chlorobenzene.

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