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Scorpion4ik [409]
2 years ago
10

A solution of 0.108 M cysteine is titrated with 0.0540 M HNO3 . The pKa values for cysteine are 1.70 , 8.36 , and 10.74 , corres

ponding to the carboxylic acid group, thiol group, and amino group, respectively. Calculate the pH at the equivalence point of the titration.
Chemistry
1 answer:
kirill [66]2 years ago
5 0

Answer:

2.698

Explanation:

Cysteine + H+ <==> cysteineH+

at the equivalence point

cosidering 1 L of cysteine solution

volume of HNO3 to reach equivalence point = 0.108 M x 1 L/0.0540 M = 2.0 L

[CysteineH+] formed = (0.108 M x 1 L)/(1.0 + 2.0) L = 0.036 M

hydrolysis of salt

cysteineH+ + H_2O <==> cysteine + H_3O+

let x amount hydrolyzed

Ka1 = [cysteine][H3O+]/[cysteineH+]

pKa1 = -log[Ka1] = 1.70

Ka = 0.02

so,

0.02 = x^2/(0.036-x)

x^2 + 0.02x - 0.00072 = 0

x = 0.002

pH at equivalence point = -log(0.002) = 2.698

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grigory [225]

Answer:

             Mass  =  6.183 g

Solution:

Step 1: Calculate number of moles of Boric acid using following formula,

                                        Molarity  =  Moles ÷ Volume

Solving for Moles,

                                        Moles  =  Molarity × Volume

Putting Values,

                                        Moles  =  0.05 mol.L⁻¹ × 2.0 L

                                        Moles  =  0.1 mol

Step 2: Calculate Mass of Boric Acid using following formula,

                                        Moles  =  Mass ÷ M.mass

Solving for Mass,

                                        Mass  =  Moles × M.mass

Putting values,

                                        Mass  =  0.1 mol × 61.83 g.mol⁻¹

                                        Mass  =  6.183 g

Flask used to prepare this solution is called as Volumetric flask. Take 2 L volumetric flask, add 6.183 g of Boric acid and fill it to the mark with distilled water.

7 0
2 years ago
Which of these was not proposed by john dalton in 1805?
wel

Answer:

Atoms are made of protons, neutrons and electrons.

Explanation:

The Dalton's atomic theory was an early attempt at describing the properties of atoms. It stipulated that atoms were the smallest indivisible particle of a substance. Chemical reactions occur as a result of a combination or separation of atoms. Atoms of the same element are exactly alike and differ from atoms of other elements. Atoms can neither be created nor destroyed.

As time went on, modern scientific evidence began to modify the original postulates of the Dalton's atomic theory. It was not postulated in 1805 that atoms were composed of subatomic particles; electrons, neutrons and protons. Dalton's theory held the atom to be 'indivisible'. However in 1897, JJ Thompson discovered the electron. Subsequently, the proton and neutrons were discovered. This shows that the atom in itself consisted of even smaller particles.

3 0
1 year ago
A semipermeable membrane separates two solutions of different concentrations. Identify which of the following statements are cor
GenaCL600 [577]

Answer:

The correct options are A, and C.

Explanation:

Osmosis: It is defined as the movement of solvent with the help of selectively semipermeable membrane into a region of where high solute concentration is present to equalize the concentration of solute on the both compartments.

Reverse osmosis: It is defined as the movement of the high concentration solvent is forced onto the lighter concentration side with the help of mechanical pressure.

5 0
1 year ago
Read 2 more answers
A liquid with a high viscosity cannot be a mixture.
enot [183]
It can be made true by changing "cannot" to "can".
5 0
1 year ago
The volume of distilled water that should be added to 10.0 mL of 6.00 M HCl(aq) in order to prepare a 0.500 M HCl(aq) solution i
bija089 [108]

Answer:

110ml

Explanation:

<em>Using the dilution equation, C1V1 = C2V2</em>

<em>Where C1 is the initial concentration of solution</em>

<em>C2 is final concentration of solution</em>

<em>V1 is intital volume of solution</em>

<em>V2 is final volume of solution.</em>

From the question , C1=6M, C2=0.5M, V1=10ml, V2=?

V2 =\frac{C1V1}{C2}

V2 =\frac{10*6}{0.5}

V2 =120ml

volume of water added = final volume -initial volume

                                    = 120-10

                                   =110ml

3 0
2 years ago
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