Find the pH of the equivalence point and the volume(ml) of 0.125M HCl needed to reach the point in titrations of: a) 65.5ml of 0.234M NH3.b) 21.8 mL of 1.11 M CH3NH2.

Answers

Answer 1

Answer:

a. 122.6 mL / pH = 4.03

b. 193.6 mL / pH = 5.73

Explanation:

In the equivalence point we know: mmoles acid = mmoles base- And the pH in a titration between a weak base and a strong base, is acid, at the equivalence point. For the volume, we can replace the equation with the data given.

a. 0.125M . volume of acid = 65.5 mL . 0.234M

Volume of acid = (65.5 . 0.234) / 0.125 = 122.6 mL

Total volume at the equivalence point = 188.1 mL

b. 0.125M . volume of acid = 21.8 mL . 1.11 M

Volume of acid = (21.8 .  1.11) / 0.125 = 193.6 mL

Let's calculate the pH. In the equilavence point we have a neutralization reaction.

a. NH₃ + HCl → NH₄Cl

All the mmoles of protons (65.5 mL . 0.234M) react to ammonia, to obtain ammonium.

New concentration is: 15.32 mmoles / 188.1 mL = 0.0814 M

This is the [NH₄⁺] to determine the pH in the acid base equilibrium.

NH₄⁺  +  H₂O  ⇄  NH₃  +  H₃O⁺      Ka

Expression for Ka = [NH₃]  . [H₃O⁺] / [NH₄⁺]

5.6×10⁻¹⁰ = x² / (15.32 - x)

(We can avoid the quadratic equation 'cause Ka is so small)

√(5.6×10⁻¹⁰ . 15.32) = x → [H₃O⁺] = 9.26×10⁻⁵

pH = - log [H₃O⁺] → 4.03

b. CH₃NH₂ + HCl → CH₃NH₃Cl

All the mmoles of protons (21.8 mL . 1.11M) react to methylamine, to obtain methylammonium.

New concentration is: 24.2 mmoles / 193.6 mL = 0.125 M

This is the [CH₃NH₃⁺] to determine the pH in the acid base equilibrium.

CH₃NH₃⁺  +  H₂O  ⇄  CH₃NH₂  +  H₃O⁺      Ka

Expression for Ka = [CH₃NH₂]  . [H₃O⁺] / [CH₃NH₃⁺]

2.7×10⁻¹¹ = x² / (0.125 - x)

(We can avoid the quadratic equation 'cause Ka is so small)

√(2.7×10⁻¹¹ . 0.125) = x → [H₃O⁺] = 1.84×10⁻⁶

pH = - log [H₃O⁺] → 5.73

Answer 2

The pH of the equivalence point of 0.125M HCl with NH₃ is 4.03 and with CH₃NH₂ is 5.73.

What is equivalence point?

In the acid - base titration, at the equivalence point equal moles of acid as well as of base are present.

First we calculate the volume of HCl by using the below equation as:

M₁V₁ = M₂V₂, where

M₁ = molarity of NH₃ = 0.234 M

V₁ = volume of NH₃ = 65.5 mL

M₂ = molarity of HCl = 0.125 M

V₂ = volume of HCl = ?

V₂ =  (65.5 . 0.234) / 0.125 = 122.6 mL

Total volume at the equivalence point = 188.1 mL

Chemical reacion will be written as:

NH₃ + HCl → NH₄Cl

All moles of protons react with moles of ammonia, so new moles (n) will be calculated as:

n = molarity × volume

n = 65.5 mL × 0.234M = 15.32 moles

Now, concentration in terms of molarity will be 15.32 mmoles / 188.1 mL = 0.0814 M

pH in the acid-base reaction due to [NH₄⁺], as:

NH₄⁺  +  H₂O  ⇄  NH₃  +  H₃O⁺

Value of Ka for this reaction is = 5.6×10⁻¹⁰

According to the ICE table, Ka equation will be written as-

5.6×10⁻¹⁰ = x² / (15.32 - x)

x = [H₃O⁺] = 9.26 × 10⁻⁵

pH = - log [H₃O⁺] = 4.03

Again we calculate the volume of HCl with the CH₃NH₂ as:

0.125M . volume of acid = 21.8 mL . 1.11 M

Volume of acid = (21.8 .  1.11) / 0.125 = 193.6 mL

Total volume at the equivalence point = 215.4 mL

Chemical reacion will be written as:

CH₃NH₂ + HCl → CH₃NH₃Cl

All moles of protons react with moles of ammonia, so new moles (n) will be calculated as:

n = 21.8 mL . 1.11M = 24.2 moles

Now, concentration in terms of molarity will be 24.2 moles / 215.4 mL = 0.11M

pH in the acid-base reaction due to [CH₃NH₃⁺], as:

CH₃NH₃⁺  +  H₂O  ⇄  CH₃NH₂  +  H₃O⁺

Value of Ka = 2.7×10⁻¹¹

According to the ICE table, Ka equation will be written as-

2.7×10⁻¹¹ = x² / (0.11 - x)

x = [H₃O⁺] = 5.4×10⁻⁶

pH = - log [H₃O⁺] = 5.73

Hence the value of pH will be 4.03 and 5.73 respectively.

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Related Questions

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Answers

Answer: 0.217 mol

Explanation:

To find the amount of moles in a 10 g sample, we need the molar mass of ethanol.

Molar Mass: 46.07 g/mol

Now that we have the molar mass, we can find moles.

[tex]10.0 g*\frac{1mol}{46.07g}=0.217 mol[/tex]

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Answer:

b. cannot exist in optically active form

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Explanation:

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Which statement best describes why a chemical property change is different from a physical change?

A. A chemical change results in a different state of matter; and a physical change results in a new substance being formed.

B. A chemical change results in a new substance being formed; whereas, a physical change will result in a different state of matter.

C. A chemical change is used by scientists to create new substances, and a physical change happens naturally.

D. A chemical change is used to identify characteristics of a substance, and a physical change identifies the behavior of a substance when in a reaction.

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Answer:

B

Explanation:

a chemical change is making a new substance and physical change with a result in a different state of matter:)

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Answers

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Answer:

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Answer:

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Answers

Answer:

Explanation:

When volume of gas is V , pressure is P and temperature is T , if n be number of moles of gas

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Answers

Answer:

Volume of water added = 148.4 mL

Explanation:

Given data:

Initial volume = 424 mL

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Solution:

Formula:

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Answers

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PLEASE HURRY WILL GIVE BRAINLEST IF ANSWERED CORRECTLY
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Answers

Answer:

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Explanation:

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Answers

Answer:

Explanation:

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A pure substance is an homogeneous material, having a composition, and

properties that are consistent through out the material.

The chemical properties of a pure substance are defined, such as the

products of its reaction can be predictable.

A chemical is pure when it consist of a single type of particle such as an

element, a molecule or a compound.

The five pure substances are presented as follows;

[tex]\displaystyle\begin{tabular}{|l|l|l|l|l|}\underline{Pure \ Substances}&\underline{Appearance}&\underline{Separaing Tech}&\underline{Boiling \ Point}&\underline{Melting \ point}\\1. Diamond&Translucent \ solid&Inseparable&3550^{\circ}&4830^{\circ}\\2. Table \ salt&White\ crystals&Insepble&801^{\circ}&1413^{\circ}\\3. Water&Tran parent \ liquid&Insepble&0^{\circ}&100^{\circ}\\4. Sugar&Whilte \ crystals&Heating&Decomposes&186^{\circ}\\5. Gold&Yellowish \ metal&Inseparable& 2700^{\circ}&1064^{\circ}\end{array}[/tex]

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Answer:

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Question:

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Answer:

Chemical change happens when a substance changes they molecular structure, it often involves change in color (rusting iron), transfer of energy (copper smelting), or gas bubbling.

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Explanation:

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Answer:

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Answers

Answer:

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Atoms in group 7a are likely to form ions with a -1 charge because they are one electron away from completing their outermost shell. The large number of protons in the middle of these atoms also causes the valence electrons to experience a stronger net force. This force also pulls strongly on the valence electrons of other atoms, causing the -1 ions we see in nature.

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Answers

Answer:

Just count all the different elements like what elemets are in there and you have to identify the number of elemenst

Explanation:

for example H20 and a chemical for example thats two so you identofy which elelments are in there doesnt matter if thered multiple of it all its asking is what id the number of elemts there meaning like one or 2 mayne six different elements

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Answers

Answer:

Ammonia is moderately a base

Ammonia is a Moderately base

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Answers

Answer:

Convection currents are caused by a temperature difference in gases and liquids. As one area becomes warmer than another the molecules have more energy and start vibrating more vigorously thus spreading out and becoming less dense. This means that the less dense parts will become more buoyant causing them to rise.

Explanation:

Answer:

Convection currents are caused by a temperature difference in gases and liquids.  

Explanation:

As one area becomes warmer than another the molecules have more energy and start vibrating more vigorously thus spreading out and becoming less dense. This means that the less dense parts will become more buoyant causing them to rise.

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Answer:

I THINK it's D, I could be incorrect, however.

Explanation:

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Answer:

No, IR should not soely be used to identify molecules

Explanation:

IR is a method that identifies the functional groups in a molecule by deducing the frequency of stretching and vibration of bonds. Each peculiar type of bond has a frequency for the vibration of each bond represented on the IR spectrum.

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Answers

Answer:

[tex]v=6.7\times 10^9\ mi/hr[/tex]

Explanation:

Given that,

The speed of light is 3×10⁸ m/s

We need to convert it into mi/hr.

Since, 1 mile = 1610 m

1 hour = 3600 s

So,

[tex]v=3\times 10^8\ \dfrac{m}{s}\\\\=3\times 10^8\ \dfrac{\dfrac{1}{1610}\ \text{miles}}{\dfrac{1}{3600}\ s}\\\\=6.7\times 10^9\ mi/hr[/tex]

So, the required speed of light is [tex]6.7\times 10^9\ mi/hr[/tex].

Match Term Definition
Pure substance A) Liquid homogeneous mixture in which the solute is distributed evenly within the solvent
Heterogeneous B) Mixture that has its different components mixed evenly within the substance
Homogeneous C) Mixture that has its different components mixed unevenly within the substance
Solution D) Consists of a single element or type of compound

Answers

Answer:

b

Explanation:

this should help

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B. Ni, Ga, Zn
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Answers

Answer:

C

Explanation:

Al=Aluminum

Mg=Magnesium

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Answers

The salt makes it rise and

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Question 10 of 12- POS
GR8 Sci U03 USA FY21 Question: 1-10
Hannah added a silvery white metal to a beaker of cold water and noticed that gas bubbles were given off and a different substance formed. When she repeated the activity with hot water she noticed the gas bubbles were
released much more rapidly. Which statement best explains why the reaction occurred faster in hot water?
M

Answers

The correct answer is Hot water increases the collision rate of molecules, causing the reaction to occur faster.

Explanation:

Temperature is directly related to the kinetic energy or movement of molecules in a substance. In this context, a higher temperature leads to more kinetic energy or more collision between molecules. At the same time, a chemical reaction involves molecules of two or more substances colliding and creating bonds to form new substances. This implies an increase in temperature means molecules colliding faster, new substances forming in a shorter time, and therefore a faster chemical reaction. According to this, the first answer is correct.

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