A chemist titrates 80.0mL of a 0.3184M pyridine C5H5N solution with 0.5397M HBr solution at 25°C . Calculate the pH at equivalence. The pKb of pyridine is 8.77.

Answers

Answer 1
Answer:

Answer:pH = 2.96

Explanation:

C5H5N + HBr --------------> C5H5N+  + Br-

millimoles of pyridine = 80 x 0.3184 =25.472mM

25.472 millimoles of HBr must be added to reach equivalence point.

25.472  = V x 0.5397

V =25.472/0.5397= 47.197 mL HBr

total volume = 80 + 47.197= 127.196 mL

Concentration of [C5H5N+] = no of moles / volume=

25.472/ 127.196= 0.20M

so,

pOH = 1/2 [pKw + pKa + log C]

pKb = 8.77

pOH = 1/2 [14 + 8.77 + log 0.20]

pOH = 11.0355

pH = 14 - 11.0355

pH = 2.96


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Ionic equation for Sr3(PO4)2 and its solubility product (Ksp)?​

Which of the following required Bohr's model of the atom to need modification ? A. Energies of electrons are quantized. B. Quantized electron energies are responsible for emission spectra lines. C. An electron's energy increases the farther it moves from the nucleus. D. Electrons do not follow circular orbits around the nucleus..

Answers

Answer:

Electrons do not follow circular orbits around the nucleus

Explanation:

Bohr's model of the atom is a combination of elements of quantum theory and classical physics in approaching the problem of the hydrogen atom. According to Neils Bohr, stationary states exist in which the energy of the electron is constant. These stationary states were referred to as circular orbits which encompasses the nucleus of the atom. Each orbit is characterized by a principal quantum number (n). Energy is absorbed or emitted when an electron transits between stationary states in the atom.

Sommerfeld improved on Bohr's proposal by postulating that instead of considering the electron in circular orbits, electrons actually orbited around the nucleus in elliptical orbits, this became a significant improvement on Bohr's model of the atom until the wave mechanical model of Erwin Schrödinger was proposed.

Answer:

Electrons do not follow circular orbits around the nucleus

Explanation:

suspension are mixtures composed of materials that are visible to the naked eyes true or false? in science subject​

Answers

Answer:

True

Explanation:

Suspensions are referred to as mixtures composed of materials which are visible to the naked eyes . They are usually insoluble in the solvent .

The mixtures which are composed of materials and at the same time non visible to the naked eyes due to their very tiny size are referred to as colloids or colloidal particles in the field of science.

Treatment of (S)-( )-5-methyl-2-cyclohexenone with lithium dimethylcuprate gives, after protonolysis, a good yield of a mixture containing mostly a dextrorotatory ketone A and a trace of an optically inactive isomer B. Treatment of A with zinc amalgam and HCl affords an optically active, dextrorotatory hydrocarbon C. Identify compounds A, B, and C, including stereochemical configurations. Be sure to explicitly draw H and both wedge/dash bonds at any configuration center.

Answers

Answer:

use google and use the first link

Explanation:

Final answer:

Treatment of (S)-( )-5-methyl-2-cyclohexenone with lithium dimethylcuprate followed by protonolysis produces dextrorotatory ketone A and a trace of isomer B. Compound A can yield optically active, dextrorotatory hydrocarbon C when treated with zinc amalgam and HCl.

Explanation:

Treatment of (S)-( )-5-methyl-2-cyclohexenone with lithium dimethylcuprate followed by protonolysis yields a mixture containing primarily a dextrorotatory ketone A and a trace of an optically inactive isomer B. Compound A can be treated with zinc amalgam and HCl to produce an optically active, dextrorotatory hydrocarbon C.

To provide a specific identification and stereochemical configuration of compounds A, B, and C, I would need additional information or further context about the starting components and reaction conditions, as well as any other relevant data or observations.

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Redox reactions stand for oxidation/reduction reactions. True or false: an oxidation reaction is always paired with a reduction reaction.

Answers

Answer:

The answer is: true

Explanation:

In redox reactions, the half-reactions of oxidation and reduction always occur simultaneously in pair.

The oxidation half-reaction involved the lost of electrons from a reduced substance (A) to form a oxidized substance (A⁺):

A ⇒ A⁺ + e-

In contrapossition, during the reduction half-reaction the oxidized substance (B⁺) gains electrons to form the reduced subtance (B):

B⁺ + e- ⇒ B

The overall redox reaction is obtained by the addition of the two half-reactions:

A ⇒ A⁺ + e-

B⁺ + e- ⇒ B

-----------------

A + B⁺⇒ A⁺ + B

The electrons gained by B are provided by A, which lost the same number of electrons. Thus, the oxidation/reduction reactions are paired.

Final answer:

Yes, it's true that an oxidation reaction always pairs with a reduction reaction, thereby making up a redox reaction where one substance is oxidized (loses electrons) and another is reduced (gains electrons). The oxidized species is the reducing agent while the reduced one is the oxidizing agent.

Explanation:

The statement is true: an oxidation reaction is indeed always paired with a reduction reaction. This can be exemplified in the redox reactions where one substance is oxidized (loses electrons) while another is reduced (gains electrons). These reactions always occur together. The species that is oxidized is called the reducing agent, while the species that is reduced is called the oxidizing agent. Therefore, in every redox reaction, there will always be an oxidation process coupled with a reduction process.

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What is the pH of a solution with hydroxide ion concentration of 0.005

Answers

Answer:

pH = 11.7

Explanation:

pOH= -log [OH]=-log[0.05]

=2.3

pOH+pH= 14

pH= 14-2.3= 11.7

From the combinations of substances listed below, which would most likely be miscible ineach other?
(33 Points)
A.polar water, nonpolar oil
B.polar vinegar, nonpolar nail polish
C. polar bleach, polar water
D.nonpolar mineral oil, polar alcohol

Answers

Answer:

C

Explanation:

polar has unequal sharing of electrons that has the lone pairs which has the electronegativity difference. can be mixed with water.

Final answer:

The combination of polar bleach and polar water would likely be most miscible with each other as substances with similar molecular structures and polarities tend to mix. This is based on the rule of 'like dissolves like' in chemistry.

Explanation:

The question is asking which combination of substances would be most likely to mix, or be miscible, in one another. Miscibility is a property in chemistry relating to whether different substances can combine into a homogeneous mixture without separating.

The rule of thumb in chemistry is 'like dissolves like' which means that substances with similar molecular structures and polarities tend to be miscible with each other. Therefore, among the provided options, the combination of polar bleach and polar water (Option C) would be the most likely to mix with each other as they are both polar substances.

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