Calculate the pH at the equivalence point for the titration of 0.200 M 0.200 M methylamine ( CH 3 NH 2 ) (CH3NH2) with 0.200 M HCl . 0.200 M HCl. The K b Kb of methylamine is 5.0 × 10 − 4 . 5.0×10−4. pH =

Answers

Answer 1

Answer:

pH = 5.85

Explanation:

The reaction of methylamine with HCl is:

CH₃NH₂ + HCl → CH₃NH₃⁺ + Cl⁻

As the titration was made with two solutions with the same molarity, the final concentration of the CH₃NH₃⁺ ion is 0.100M ([CH₃NH₃⁺] = 0.100M)

Then, the conjugate acid will be in equilibrium with water as follows:

CH₃NH₃⁺(aq) + H₂O(l) ⇄ CH₃NH₂(aq) + H₃O⁺(aq)

And the equilibrium constant, Ka, of this reaction is:

Kw/Kb = Ka =  1.0x10⁻¹⁴ / 5.0x10⁻⁴= 2x10⁻¹¹

2x10⁻¹¹ =  [CH₃NH₂] [H₃O⁺] / [CH₃NH₃⁺]

As both CH₃NH₂ and H₃O⁺ comes from the same equilibrium we can say:

[CH₃NH₂] = [H₃O⁺] = X

And as we know [CH₃NH₃⁺] = 0.100M:

2x10⁻¹¹ =  [X] [X] / [0.100M]

2x10⁻¹² = X²

X = 1.414x10⁻⁶M = [H₃O⁺]

And as pH= -log [H₃O⁺]

pH = 5.85


Related Questions

For a nucleus to go through mitosis,
A. it must start with two sets of chromosomes (diploid)
B. it must start with one set of chromosomes (haploid)
C. it can start with one set or two sets of chromosomes (haploid or diploid)
D. it can start with any number of chromosomes

Answers

Answer:

A

Explanation:

I had this in a test

Which of the following is the best hypothesis?
A. If paper is burned, the products will be carbon dioxide and water.
B. At what temperature does a piece of notebook paper start to burn?
C. Some people use burning paper to help get a campfire started.
D. You should recycle paper instead of burning it.

Answers

Answer:

THE CORRECT ANSWER IS A

sorry for caps

calculate the percentage mass of hydrogen in hydrochloric acid, HCI​

Answers

Answer:

To find the mass percent of hydrogen in hydrogen chloride, we must divide the weight of the hydrogen atom alone by the weight of the entire molecule. Then we multiply by 100% to find the percentage. Thus, 2.77% of the mass of hydrogen chloride is hydrogen.

Explanation:

i hope you understand better

Question 1 of 10
What variable represents thermal energy in the equation Q=MAT?
O A. The variable e
O B. The variable Q
O c. The variable
O D. The variablem

Answers

Option b I think :) hope this helped!

When a lead acid car battery is recharged by the alternator, it acts essentially as an electrolytic cell in which solid lead(II) sulfate PbSO4 is reduced to lead at the cathode and oxidized to solid lead(II) oxide PbO at the anode. Suppose a current of 96.0A is fed into a car battery for 37.0 seconds. Calculate the mass of lead deposited on the cathode of the battery.

Answers

Answer: 3.73 grams

Explanation:

[tex]Q=I\times t[/tex]

where Q= quantity of electricity in coloumbs

I = current in amperes = 96.0 A

t= time in seconds = 37.0 sec

[tex]Q=96.0A\times 37.0s=3552C[/tex]

The reaction at cathode is:

[tex]Pb^{2+}+2e^-\rightarrow Pb[/tex]

[tex]96500\times 2=193000Coloumb[/tex] of electricity deposits 1 mole of  

3552 C of electricity deposits =[tex]\frac{1}{193000}\times 3552=0.018moles[/tex] of Pb

[tex]\text {mass of Pb}={\text{moles}\times {\text{Molar mass}}[/tex]

[tex]\text {mass of Pb}={0.018}\times {207.2g/mol}=3.73g[/tex]

Thus mass of lead deposited is 3.73 g

calculate the percentage mass of oxgen in water, H2O​

Answers

Answer:

the mass of oxygen in water is 16.00.

water, h2o, has a molar mass of 18.015
oxygen has a molar mass of 15.999

15.999/18.015 is 0.880932556
multiply this by 100 to get:
88.8% of oxygen


hope this helped!

Exit ticket: Name the 2 factors that Terrestrial Biomes are separated by ___________ & ________

Answers

Answer:

temperature and rainfall

Explanation:

What is the other product for this reaction ? H3PO4 + Ca(OH)2 —> H20 + _________

Answers

*☆*――*☆*――*☆*――*☆*――*☆*――*☆*――*☆*――*☆**☆*――*☆*――*☆*――*☆

Answer: h3po4 + ca(oh)2 = h2o + ca3(po4)2

Explanation:

I hope this helped!

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- Zack Slocum

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How many Protons, Electrons and Neutrons does Helium-6 have?

Answers

Answer:

12 neutrons

2 protons

2 electrons

Answer:

Hello There!!

Explanation:

Helium 6 has:

-two protons

-two electrons

-two neutrons

hope this helps,have a great day!!

~Pinky~

What type of solution would have a pH of 8 ?

Answers

*☆*――*☆*――*☆*――*☆*――*☆*――*☆*――*☆*――*☆**☆*――*☆*――*☆*――*☆

Answer: Weak base

Explanation:

I hope this helped!

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Answer and Explanation:

Solutions that have a pH of 8 would be considered a Weak Base.

This is because a weak base is a base that, upon dissolution in water, does not dissociate completely.

Solutions/liquids that have a pH higher than a pH of 7 are basic solutions, while solutions/liquids that have a pH lower than a pH of 7 are acidic solutions.

When the pH level is closer to 7, it is weak, and when it is far from 7, like if it is 1 or 12, then it is a strong acid/base.

#teamtrees #PAW (Plant And Water)

A pair of molecular orbitals is formed by.

Answers

“Bonding molecular orbitals are formed by... in-phase combinations of atomic wave functions, and electrons in these orbitals stabilize a molecule.”

Which tissues are in both leaves and roots? (select all that apply) A. pistil B. stomata C. xylem D. phloem I NEED ASNSWER NOW

Answers

Answer:

Xylem and Phloem

Explanation:

cause

What forms an electric current?

Answers

Electric current is electric charge in motion. It can take the form of a sudden discharge of static electricity, such as a lightning bolt or a spark between your finger and a ground light switch plate. ... Protons have positive charge, while electrons have negative charge. Hope this helps

What does the addition of a catalyst do to a reaction?

Answers

Answer:

B

Explanation:

It lowers the activation energy required therefore speeding up the reaction

1/5 divided by 3/4 fraction

Answers

Answer:

4/15

Explanation:

we can write out an equation by doing (1/5 ÷ 3/4) and then switch the sign to multiplication and we can keep the first fraction the same (in this case 1/5) and then we flip the second fraction BUT when we flip the second fraction upside-down we have to change the symbol to multiplication (1/5x4/3)

then after that all we do is multiply the denominators and numerators :)

1 x 4 = 4

_______

5 x 3 = 15

answer would be 4/15

PLEASE HELP!!!!!!!
25.0g of Aluminum metal is combined with
45.Og Copper(ll) Chloride to produce Aluminum Chloride
and Copper metal
1. Write and balance the chemical equation.
2. Write the needed mole ratio between reactants.
3. What is the mole ratio you have from the data?
4. What is in excess and what is limited? (Show Work)
5. What is the theoretical yield of Aluminum Chloride?

Answers

Answer: 1. [tex]2Al+3CuCl_2\rightarrow 2AlCl_3+3Cu[/tex]

2. 3 moles of [tex]CuCl_2[/tex] : 2 moles of [tex]Al[/tex]

3. 0.33 moles of [tex]CuCl_2[/tex] : 0.92 moles of [tex]Al[/tex]

4. [tex]CuCl_2[/tex] is the limiting reagent and [tex]Al[/tex] is the excess reagent.

5. Theoretical yield of [tex]AlCl_3[/tex] is 29.3 g

Explanation:

To calculate the moles :

[tex]\text{Moles of solute}=\frac{\text{given mass}}{\text{Molar Mass}}[/tex]    

[tex]\text{Moles of} Al=\frac{25.0g}{27g/mol}=0.92moles[/tex]

[tex]\text{Moles of} CuCl_2=\frac{45.0g}{134g/mol}=0.33moles[/tex]

The balanced chemical equation is:

[tex]2Al+3CuCl_2\rightarrow 2AlCl_3+3Cu[/tex]  

According to stoichiometry :

3 moles of [tex]CuCl_2[/tex] require = 2 moles of [tex]Al[/tex]

Thus 0.33 moles of [tex]CuCl_2[/tex] will require=[tex]\frac{2}{3}\times 0.33=0.22moles[/tex]  of [tex]Al[/tex]

Thus [tex]CuCl_2[/tex] is the limiting reagent as it limits the formation of product and [tex]Al[/tex] is the excess reagent.

As 3 moles of [tex]CuCl_2[/tex] give = 2 moles of [tex]AlCl_3[/tex]

Thus 0.33 moles of [tex]CuCl_2[/tex] give =[tex]\frac{2}{3}\times 0.33=0.22moles[/tex]  of [tex]AlCl_3[/tex]

Theoretical yield of [tex]AlCl_3=moles\times {\text {Molar mass}}=0.22moles\times 133.34g/mol=29.3[/tex]

Thus 29.3 g of aluminium chloride is formed.

Which of the following statements about electronegativity are true? (Select that all apply)

Answers

Answer: The question is incomplete and the options are not given but here are d options from another website.

a. Electronegativity increases as you move to the right of the periodic table.

B. Electronegativity is the ability of an atom to attract electrons.

c. A very electronegative atom easily gives up electrons.

d. Electronegativity increases with a decreased number of protons.

The correct options are

a. Electronegativity increases as you move to the right of the periodic table.

B. Electronegativity is the ability of an atom to attract electrons.

d. Electronegativity increases with a decreased number of protons.

Explanation:

This is because Electronegativity is the ability of an element to attract pair of electrons to itself.

Electronegativity increases as a result of increase in protons and when there is more electron pull.

As, the size of an element decreases, the valence electrons are attracted near to the nucleus. Therefore, there is increase in attraction between shared electron and nucleus.

Balancing Chemical Equations

Answers

*☆*――*☆*――*☆*――*☆*――*☆*――*☆*――*☆*――*☆**☆*――*☆*――*☆*――*☆

Answer: C3H8 + 5O2 ---> 3CO2 + 4H2O

Explanation: This is an example!

I hope this helped!

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- Zack Slocum

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At which point in its swing does the pendulum have the least gravitational potential energy

Answers

Answer:

a

Explanation:

a

which answer? Is this

Answers

Answer:

law of segregation

have a good day!

Explanation:

Which of the following wavelengths has the lowest frequency?
10mm
10nm
10km
10cm
10m

Answers

Answer:

10m es su respuesta

Explanation:

espero te sirva

Heat transfer that occurs within or between solid objects is called

Answers

Answer:

conduction

Explanation:

The answer is Conduction

Calculate the number of moles in 75 g of Glucose

Answers

Answer:

0.4mol

Explanation:

number of moles(n)=mass/molar mass of glucose(M)

n=75g/180.156M

n=0.4mol

What chemical reaction affects thermal energy?

Answers

The Heat of Reaction is the change in the enthalpy of a chemical reaction. In endothermic reactions, (ΔH>0) thermal energy is absorbed via the reaction.

There are eight diastereomers of 1,2,3,4,5,6-hexachlorocyclohexane. One of them is drawn. Draw the other seven in the cyclohexane framework below (5 points). One isomer loses HCl in an E2 reaction nearly 1000 times more slowly than the others. Circle the isomer that reacts so slowly, draw its corresponding chair conformers and explain the reason for the slow rate. (5 points).

Answers

Answer:

Attached below diagram of the eight diastereomers

The Isomer that reacts so slowly is DIASTEREOMER 8

Explanation:

The Isomer that reacts so slowly is DIASTEREOMER 8 in an E2 reaction and this is because no pair of chlorine and hydrogen atoms can assume the anti-periplanar orientation that is preferred in an E2 elimination

attached below is Diagram of the eight diastereomers ( screen shot from my drawing tool )

Solution Mass of NaCl (9) Volume of water (mL)
A
5.0
50.0
B
5.0
75.0
с
5.0
100.0
D
5.0
125.0
Which of the solutions has the highest salt concentration?
O A Solution B
B. Solution A
O
C. Solution C
D. Solution D

Answers

Divide the volume of water with mass of salt and multiply with 100 you'll get the concentration percentage

answer is B, because solution A's percentage is 10%

brainliest plz

the ideal of stationary orbit was first given by?​

Answers

Answer:

Neil Bohr

Explanation:

Thank me latur✊

2. You have a rock with a
volume of 15cm3 and a
mass of 45 g. What is its
density?

Answers

Answer:

3 g/cm³

Explanation:

Density= Mass divided by Volume

45÷15= 3

What observations and reasoning led to the development of Hubble's Law?

Answers

Answer:

Hubble's law says that the universe is expanding outward.

Explanation:

Actually Hubble's law was discovered before the Big Bang theory was formulated. The Big Bang Theory is an attempt to explain the observations that led to Hubble's Law.Before the 1900s the theory was that the universe was eternal and self existent. The idea was that the universe was in a steady state having always existed and would always continue to exist. Albert Einstein even changed the equations in his general theory of relativity to reflect the idea of a steady state. Later he called putting in a fudge factor to result in a steady state the worse mistake of his life.

Hubble observed that most of the universe has a red shift indicating that the universe is expanding and moving away from itself. The further out that the universe is observed the faster it is moving apart.

These observations were inconsistent with a steady state universe.

The Big Bang theory extrapolated backwards. If the universe is expanding and spreading out from itself then further back in time the universe was closer together. The Theory explained Hubble's observations by the idea that at the beginning of time ( for our universe) all the matter and energy were together in one place.

This super dense ball of matter and energy then exploded outwards creating space and time as it is presently observed. The question was would the forces of gravity and black holes bring the matter and energy back together again. The answer found in 1998 was no. The rate of the expansion of the universe is increasing not slowing down and the universe will not collapse back into the super dense ball of matter that it began as.

The Big Bang Theory postulated based on the empirical evidence that our universe had a beginning and it will eventually cease to exist. The conclusion based on Hubble's observations is that matter and energy are not eternal and self existent.

vitamin B information please​

Answers

B vitamins play a vital role in maintaining good health and well-being. As the building blocks of a healthy body, B vitamins have a direct impact on your energy levels, brain function, and cell metabolism.

Hope this helps; have a great day!

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