A 25.0-mL sample of 0.150 M hydrazoic acid, HN3, is titrated with a 0.150 M NaOH solution. What is the pH after 13.3 mL of base is added? The Ka of hydrazoic acid = 1.9 x 10-5.

Answers

Answer 1

Answer:

pH ≅ 4.80

Explanation:

Given that:

the volume of HN₃ = 25 mL = 0.025 L

Molarity of HN₃ = 0.150 M

number of moles of HN₃ = 0.025 × 0.150

number of moles of HN₃ =  0.00375  mol

Molarity of NaOH = 0.150 M

the volume of NaOH = 13.3 mL = 0.0133

number of moles of NaOH = 0.0133× 0.150

number of moles of NaOH = 0.001995 mol

The chemical equation for the reaction of this process can be written as:

[tex]HN_3 + OH- ---> N^-_{3} + H_2O[/tex]

1 mole of hydrazoic acid react with 1 mole of hydroxide to give nitride ion and water

thus the new number of moles of HN₃ = 0.00375 - 0.001995 = 0.001755 mol

Total volume used in the reaction =  0.025 +  0.0133 = 0.0383  L

Concentration of [tex]HN_3[/tex] = [tex]\dfrac{0.001755}{0.0383}[/tex] = 0.0458 M

Concentration of [tex]N^{-}_3[/tex] = [tex]\dfrac{ 0.001995 }{0.0383}[/tex] = 0.0521 M

GIven that :

Ka = [tex]1.9 x 10^{-5}[/tex]

Thus; it's pKa = 4.72

[tex]pH =4.72 + log(\dfrac{ \ 0.0521}{0.0458})[/tex]

[tex]pH =4.72 + log(1.1376)[/tex]

[tex]pH =4.72 + 0.05598[/tex]

[tex]pH =4.77598[/tex]

pH ≅ 4.80

Answer 2

The pH of the solution 0.150 M hydrazoic acid after 13.3 mL of NaOH base is added is 4.80.

How we calculate the pH?

pH of the given solution will be used by using the following equation:

pH = pKa + log[conjugate base] / [weak acid]

Given chemical reaction will be represented as:

HN₃ + OH⁻ → N₃⁻ + H₂O

Moles will be calculated as:

n = M×V, where

M = molarity

V = volume

Moles of 0.150 M hydrazoic acid = (0.150M)(0.025L) = 0.00375  mol

Moles of 0.150 M NaOH = (0.0133)(0.150) = 0.001995 mol

From the above calculation it is clear that moles of hydrazoic acid is present in excess and it will be:

0.00375 - 0.001995 = 0.001755 mol

And 0.001995 mol of N₃⁻ is preduced by the reaction.

Total volume of the solution = 0.025 +  0.0133 = 0.0383  L

To calculate the pH after titration, first we have to calculate the concentration in terms of molarity of N₃⁻ and HN₃ as:

[N₃⁻] = 0.001995 mol / 0.0383  L = 0.0521 M

[HN₃] = 0.001755 mol / 0.0383  L = 0.0458 M

Ka for HN₃ = 1.9 × 10⁻⁵

pKa = -log( 1.9 × 10⁻⁵ ) = 4.72

On putting all these values on the above equation, we get

pH = 4.72 + log (0.0521) / (0.0458)

pH = 4.80

Hence, pH of the solution is 4.80.

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Related Questions

Which correctly lists three characteristics of minerals?
solid, crystal structure, definite chemical composition
organic, crystal structure, definite chemical composition
human-made, solid, organic
crystal structure, definite chemical composition, human-made

Answers

Answer:a

Explanation:

The three characteristics of minerals are that they are solid, have definite crystal structure and definite chemical composition.

What are minerals?

Minerals are defined as a chemical compound  which has a well -defined composition and possesses a specific crystal structure.It occurs naturally in the pure form.

If a compound occurs naturally in different crystal structure then each structure is considered as a different mineral.The chemical composition of a mineral varies  depending on the presence of small impurities which are present in small quantities.

Some minerals  can have variable proportions of two or more chemical elements  which occupy equivalent position in the crystal structure.It may also have variable composition which is split into separate species.

Physical properties of minerals include color,streak, luster,specific gravity  and cleavage.

Learn more about minerals ,here:

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(a) How many stereoisomers are possible for 4-methyl-1,2-cyclohexanediol? ___ (b) Name the stereoisomers formed by oxidation of (S)-4-methylcyclohexene with osmium tetroxide. If there is only one stereoisomer formed, leave the second space blank. Isomer #1: Isomer #2: (c) Is the product formed in step (b) optically active? _____

Answers

Answer:

See explanation

Explanation:

For the first part of the question, we have to check the chiral carbons in 4-methyl-1,2-cyclohexanediol. In this case carbons, 1 and 2 are chiral, if we have 2 chiral carbons we will have 4 isomers. We have to remember that formula 2^n in which "n" is the number of chiral carbons, so:

2^n = 2^2 = 4 isomers

And the isomers that we can have are:

1) (1R,2S)-4-methylcyclohexane-1,2-diol

2) (1S,2S)-4-methylcyclohexane-1,2-diol

3) (1S,2S)-4-methylcyclohexane-1,2-diol

4) (1S,2R)-4-methylcyclohexane-1,2-diol

See figure 1

For the second part of the question, we have to remember that the oxidation with [tex]OsO_4[/tex] is a syn addition. In other words, the "OHs" are added in the same plane. In this case, we have the methyl group with a wedge bond, so the "OH" groups will have a dashed bond due to the steric hindrance. Due to this we only can have 1 isomer ((1S,2R,4S)-4-methylcyclohexane-1,2-diol). Finally, on this molecule, we dont have any symmetry planes (this characteristic will cancel out the optical activity), so the product of this reaction has optical activity.

See figure 2

I hope it helps!

Draw the structure 2 butylbutane

Answers

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Explanation:

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Answers

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[tex]Pb(CO_{3})_{2} \\Pb(NO_{3})_{4} \\FeCO_{3}\\Fe(NO_{3})_{2}[/tex]

Explanation:

[tex]Pb^{4+}(CO_{3}^{2-})_{2} --->Pb(CO_{3})_{2} \\Pb^{4+} (NO_{3}^{-})_{4} --->Pb(NO_{3})_{4} \\Fe^{2+} CO_{3}^{2-} --->FeCO_{3}\\Fe^{2+} (NO_{3}^{-})_{2}--->Fe(NO_{3})_{2}[/tex]

which process is used to produce gases from solutions of salts dissolved in water or another liquid?

A.Electrolysis
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C.Ionic bonding
D. Polar covalent bonding

Answers

Answer:

A.Electrolysis

Explanation:

A.Electrolysis

For example,  electrolysis of solution of NaCl in water gives H2 and O2.

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Answers

Answer:

The lewis structure of the compounds can be drawn by making the skeleton of the molecule first. Then the different atoms are arranged and the electrons are arranged in their bonding pattern. The lone pair of the atoms, which are not involved in the bonding are represented by the dots.

So the lewis structures of both the compound methyl mercaptan has been in the attached image:

Spelling of methyl metcaptain is wrong, the correct spelling is methyl mercaptan.

Answer:

Methyl mercaptan is also known as Methanethiol with the chemical formula  CH3SH and it is an organosulfur compound.

For lewis structure of methyl mercaptan (CH3SH), there are total 14 valence electrons. Four hydrogen atoms has one valence electron each, carbon has four valence electrons and sulfur has six valence electrons. Carbon form one bond with three hydrogen atoms by sharing one electron with each, carbon form one single bond with sulfur atom by sharing one electron with it and sulfur form one single bond with hydrogen. Sulfur left with four unpair electrons.

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