A mixture is prepared using 27.00 mL of a 0.0758 M weak base (pKa=4.594) , 27.00 mL of a 0.0553 M weak acid (pKa=3.235) and 1.00 mL of 1.25×10−4 M HIn and then diluting to 100.0 mL, where HIn is the protonated indicator. The absorbance measured at 550 nm in a 5.000 cm cell was 0.1102 . The molar absorptivity (????) values for HIn and its deprotonated form In− at 550 nm are 2.26×104 M−1cm−1 and 1.53×104 M−1cm−1 , respectively. What is the pH of the solution?

Answers

Answer 1

Answer:

pH = 4.164

Explanation:

The first process is to find the initial moles for the base (B) & the acid (HA)

i.e.

[tex]= \dfrac{27 mL \times 0.0758 \ moles \ \ of \ B}{1000 \ mL}[/tex]

[tex]=0.0020466[/tex]

[tex]\simeq 2.047\times 10^{-3} \ moles \ of \ B[/tex]

[tex]= \dfrac{27 mL \times 0.0553 \ moles \ \ of \ HA}{1000 \ mL}[/tex]

[tex]=0.0014931[/tex]

[tex]\simeq 1.493\times 10^{-3} \ moles \ of \ HA[/tex]

The acid with base reaction is expressed as;

          HA              +      B         →             A⁻            +         HB⁺

to    1.493 × 10⁻³       2.047 × 10⁻³             -                         -

    -  1.493 × 10⁻³       1.493 × 10⁻³         1.493 × 10⁻³         1.493 × 10⁻³

            0                    5.54 × 10⁻⁴         1.493 × 10⁻³         1.493 × 10⁻³

From observation; both the acid & base weak

Given that:

The pKa for base = 4.594

The pKa for acid = 3.235

Recall that;

pKa = -log Ka

So; Ka = [tex]\mathbf{10^{-Ka}}[/tex]

By applying this:

For Base; Ka = [tex]10^{-4.594}[/tex] = 2.5468 × 10⁻⁵

For Acid:  Ka = [tex]10^{ -3.235}[/tex] = 5.821 × 10⁻⁴

After the reaction; we have the base with its conjugate acid & conjugate base of acid; Thus, since the conjugate acid of the base possesses a higher value of K, it is likely it would be the one to define the pH of the solution.

By analyzing the system, we have:

              HB⁺         + H₂O           ↔           B          +            H₃O⁺

     [tex]\dfrac{1.493\times 10^{-3}}{0.1 \ L}[/tex]                                 [tex]\dfrac{5.54\times 10^{-4}}{0.1 \ L}[/tex]

to   0.01493 M                                 0.00554   M

  -      x                                                   x                                x

    0.01493 - x                                 0.00554 - x                     x

Thus;

[tex]2.5468 \times 10^{-5} = \dfrac{(0.00554 -x)\times x}{(0.01493-x)}[/tex]

Using the common ion effect;

0.00554 - x   [tex]\simeq[/tex]  0.00554   &

0.01493 -  x   [tex]\simeq[/tex]   0.01493

[tex]x = \dfrac{2.5468 \times 10^{-5} \times 0.01493}{0.00554}[/tex]

x =  [H₃O⁺] = 6.8635  × 10⁻⁵

pH = -log(6.8635  × 10⁻⁵)

pH = 4.164


Related Questions

name the group and period of an element having atomic number 21​

Answers

Answer:

The element in question here is Scandium, with an atomic number of 21. It is situated in Group 3 and Period 4 of the Periodic Table.

Explanation:

Hope this helped!

Scandium has an atomic value of 21 it is in group 3, period 4 of the periodic table

Question 1 / 1
Which of the following is a covalent bond?
A. CO2
B. NaCl
C. Fe2O,

Answers

Answer:

Chemistry deals with matter, and there is a tremendous variety of matter in the universe. The behavior of matter depends on the type of elements that are present and on the structure of those elements—how they are connected to make a molecule. In this exercise, you will evaluate some representative models to develop the rules used to classify a compound, to predict the formula of a compound, and to name the compound. This exercise is just the beginning of the work needed to be done to master the rules of writing formulas and nomenclature. Your textbook has tables of the names and formulas of common cations and anions, and discusses the rules of nomenclature in detail. You will need to spend some time with this material, as the formal rules of nomenclature may not be presented in lecture, although they will certainly be used in discussions of Lewis structures and reaction chemistry.

Explanation:

In a covalent compound, valence electrons are shared between the two atoms in the bond. These can be evenly shared (covalent bond) or unevenly shared (polar covalent bond). In an ionic bond, electrons are localized to one of the atoms (giving it an overall negative charge), while the other atom has an overall positive charge. The difference in electronegativity between the two atoms in the bond can help predict whether the bond is likely to be ionic, covalent, or polar covalent, as can the type of atoms involved (metals or non-metals). A bond with two identical atoms is always pure covalent, while a covalent bond with two different atoms is likely to be polar covalent.

Which part of the immune system can be "trained" using vaccines?

Answers

The adaptive immune system, because it is more specific to the foreign substances in the body and adapts to remove or fight them

explain 5 the major innovation made from Abacus to the present fifth generation​

Answers

Answer:

The major innovation made from Abacus to the present fifth generation​ is explained below in details.

Explanation:

Industrial Age - 1600

John Napier, a Scottish noble and diplomat consecrated much of his holiday time to the learning of mathematics. He was particularly engrossed in devising methods to aid estimates. His most famous offering was the discovery of logarithms. He listed logarithmic measures on a set of 10 board rods and thus was capable to do multiplication and division by equaling up numbers on the poles. These became recognized as Napier’s Bones.

Law of Universal Gravitation (what factors affect gravity and how?)

Answers

Explanation:

Hey there!

According to the law of gravitation, the factors that affects the gravity are:

Mass of the heavenly bodies.Distance from the centre of the body to next body.

Mass of heavenly bodies:The mass of heavenly bodies affect the gravity. We know that gravity is directly proportional to the mass of heavenly bodies. so, when the mass is more there is more gravity and where there is less mass there is less gravity.

Distance from the centre of the body to next body: It is one of the factor to influence gravity. When there is more distance there is less gravity and where there is distance more force is there. Is means gravity is inversely proportional to the distance between the bodies.

Hope it helps...


Explain how atomic
radius, valence electrons
and effect nuclear charge
creates the trend for metal
reactivity.

Answers

Answer:A higher effective nuclear charge causes greater attractions to the electrons, pulling the electron cloud closer to the nucleus which results in a smaller atomic radius. Down a group, the number of energy levels (n) increases, so there is a greater distance between the nucleus and the outermost orbital.

Answer:

A higher effective nuclear charge causes greater attractions to the electrons, pulling the electron cloud closer to the nucleus which results in a smaller atomic radius. Down a group, the number of energy levels increases, so there is a greater distance between the nucleus and the outermost orbital.Explanation:

An elemental metal contains how many types of atoms?
a. 1
b. 2
c. 3
d. 4

Answers

Answer:

a

Explanation:

all elemental metals are made up of only one type of element

Answer:

It is 1.

Explanation:


PLEASEEE HELP ?!?!?!

which of the following processes provide evidence of the particulate nature of matter
I. Diffusion
II. Filtration
III. Osmosis

A. I and II only
B. I and III only
C. II and III only
D. I, II and III​

Answers

Answer:

B

Explanation:

I think the answer is Diffusion and Osmosis

The processes that provide evidence of the particulate nature of matter would be diffusion and osmosis.

Matter is defined as anything with mass/weight and able to occupy space. Matters could be molecules of solid, liquid, or gases. The molecules of each category of matter have their specific characteristics.

Molecules of liquids and gases are able to diffuse. Diffusion is defined as the movement of molecules from the region of high concentration to the region of low concentration.

Molecules of solids in the dissolved form are also able to diffuse. Water molecules are also able to move from the region of high to the region of low water potentials by osmosis in the presence of a semi-permeable membrane.

Thus, both diffusion and osmosis back up the particulate nature of matter.

More on the particulate nature of matter can be found here: https://brainly.com/question/15230454?referrer=searchResults

for tour substances.
Melting and Boiling
Points of Substances
Name
Melting Boiling
Point (°C) Point (°C)
-101
-35
-210
- 196
Chlorine
Nitrogen
Oxygen
Hydrogen
-218
183
-259
-253
Which substance is a solid at -200°C?

Answers

Oxygen would be the answer because melting point is top

What happens to molecular energy(heat) in water when water vapor becomes a liquid?
Group of answer choices
Water vapor gives up heat energy.

Water vapor absorbs heat energy.

As water's mass increases it absorbs energy.

Water vapor retains the same heat energy.

Answers

Answer:

Water vapor retains the same heat energy.

Answer:

water vapor gives up heat energy.

Explanation:

Took a quiz and got it right

A paint chip is placed in ethanol and curls what type of paint is it

Answers

Answer:

it is probably acrylic or latex

Explanation:

There are two types of chemical compound one is covalent compound and other is ionic compound, covalent compound formed by sharing of electron and ionic compound formed by complete transfer of electron. Therefore, the type of paint is  acrylic or latex.

What is chemical Compound?

Chemical Compound is a combination of molecule, Molecule forms by combination of element and element forms by combination of atoms in fixed proportion.

An ionic compound is a metal and nonmetal combined compound.  Ionic compound are very hard. They have high melting and boiling point because of strong ion bond.  If the chip remains flat when put in ethanol, it is probably an oil-based paint. If the chip curls, it is probably acrylic or latex. So, The type of paint is  acrylic or latex.

Therefore, the type of paint is  acrylic or latex.

To learn more about chemical compound, here:

brainly.com/question/26487468

#SPJ2

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Answers

Answer:

daddy chill

Explanation:

What is the name of the compound with the formula LiNO3?

Answers

Answer:

Lithium nitrate

Explanation:

Lithium nitrate is an inorganic compound with the formula LiNO3. It is the lithium salt of nitric acid (an alkali metal nitrate).

How does adding a lone pair affect the position of existing atoms and lone pairs

Answers

Answer:

How does adding a lone pair affect the position of existing atoms and lone pairs? It decreases the angles between the atoms - the atoms are moving closer because they are being repelled further away from the lone pairs then they are from the other atoms

Explanation:

hope it helps!

They get closer together, the bond angle decreases, etc.

Describe the reaction of zinc with sulphuric acid​

Answers

Answer:

Zinc reacts with dilute sulphuric acid to produce hydrogen gas (H2) and zinc sulphate. This is an example of displacement reaction of a non-metal by a metal. ... ZnSO4 is different in chemical composition and chemical properties than Zn and H2SO4 so it is a chemical change.

Answer:

Reaction of Zinc with Dilute Sulphuric Acid

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In the acetylene torch, acetylene gas (C2H2)(C2H2) burns in oxygen to produce carbon dioxide, water, and energy: 2C2H2(g)+5O2(g)⟶Δ4CO2(g)+2H2O(g)2C2H2(g)+5O2(g)⟶Δ4CO2(g)+2H2O(g) You may want to reference (Pages 241 - 243) Section 7.7 while completing this problem. Part A How many moles of O2O2 are needed to react with 1.85 molmol of C2H2C2H2? Express your answer to three significant figures and include the appropriate units. nn(O2O2) = nothingnothing SubmitRequest Answer

Answers

Answer:

4.63 mol

Explanation:

Step 1: Write the balanced complete combustion reaction of acetylene

2 C₂H₂(g) + 5 O₂(g) ⟶ 4 CO₂(g) + 2 H₂O(g)

Step 2: Establish the appropriate molar ratio

According to the balanced equation, the molar ratio of C₂H₂ to O₂ is 2:5.

Step 3: Calculate the number of moles of O₂ needed to react with 1.85 moles of C₂H₂

We will use the stoichiometric molar ratio.

1.85 mol C₂H₂ × (5 mol O₂/2 mol C₂H₂) = 4.63 mol O₂

middle school science help please

Answers

Answer:

The answer is 'All of the above'

Explanation:

because the hydrogen ions are represented by the symbol H+, they increase the PH value of a solution if less amount is added but they decrease the PH value of a solution if a larger amount of hydrogen ions are added but still they increase the PH value, and of course, they contribute to a solution by a base.

Answer:

Hydrogen ions are represented by H+.

Explanation:

Hydrogen ions usually decreases the pH value when added to a solution.Hydrogen ions are contributed to a solution by a acid.

how is the strength of an acid affected by the number of hydrogen ions it contains​

Answers

More the no. of hydrogen ions more is the solution acidic.

pH means the power of hydrogen that determines the concentration of hydrogen ions or the level of acidiy or basicity of a solution.

so more the hydrogen ions more will be the Power of Hydrogen (pH) and thus more wil be the acidity.

Which event would most likely lead to a thunderstorm g i v i n g b r a i n l e s i t HELP
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Answers

Answer:

A

Explanation:

hope it helps

Answer:

A

Explanation:

I got right

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Answers

Answer: Peer-reviewed journal article is the most useful because the information in them had been carefully scrutinized and aproved by people who are experts in that particular field.

What type of reaction occurs between an element and a compound?

Answers

Answer:

exothermic reaction

Explanation:

because it occurs in the presence of heat

How can the rate of a reaction be increased?

(A) decreasing the amount of reactants

(B) having more surface area

(C) diluting a solution

(D) lowering the temperature

Answers

Explanation:

Rate of reaction can be increased by having more surface area.

Therefore,

Option B is correct✔

Answer:

b

Explanation:

Balance this equation.
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Answers

Answer:

1Mg + 1Cl2 = 1MgCl2

Explanation:

Hi! When balancing an equation, you want to make sure that there are equal amounts of each element on both sides. When looking at the equation that you provided in the question, look and count how many of each element are on each side. I can see that there is 1 Mg ion on the left and 1 Mg ion on the right. There are also 2 Cl ions on the left and 2 Cl ions on the right. Because they are already equal, the coefficients in front of each compound will be 1. If the amounts were different on each side, that is when you would need to add different coefficients.

Hope this helps! Let me know if you have any other questions about this!

Which type of energy is the tree changing the light energy into?

Answers

Answer: Chemical energy

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Answer:

chemical energy

In this case plants convert light energy into chemical energy, (in molecular bonds), through a process known as photosynthesis. Most of this energy is stored in compounds called carbohydrates. The plants convert a tiny amount of the light they receive into food energy.

Explanation:

tide occur in ocean but not in lake why​

Answers

Answer:

Because while our lakes are Great, they're comparatively much smaller than oceans. And the gravitational pull isn't strong.

If 33.9g NaCl are mixed into water and the total mass is 578g, what is the CHANGE in freezing if Kb= - 1.82C/M (molal)? Assume NaCl does not dissociate in solution.

Answers

Answer:

-1.82 °C

Explanation:

Step 1: Given data

Mass of NaCl (solute): 33.9 gMass of water (solvent): 578 g = 0.578 kgFreezing point depression constant for water (Kb): -1.82 °C/m

Step 2: Calculate the molality of the solution

We will use the following expression.

m = mass of solute / molar mass of solute × kg of solvent

m = 33.9 g / 58.44 g/mol × 0.578 kg

m = 1.00 m

Step 3: Calculate the freezing point depression (ΔT)

The freezing point depression is a colligative property that, for a non-dissociated solute, can be calculated using the following expression:

ΔT = Kb × m

ΔT = -1.82 °C/m × 1.00 m

ΔT = -1.82 °C

What are chemical equations used to represent?​

Answers

Answer:

A chemical equation is the symbolic representation of a chemical reaction. The reactants (the starting substances) are written on the left, and the products (the substances found in the chemical reaction) are written on the right.

Explanation:

pliz mark brainliest

Explanation:

chemical equations are used to represent a certain reaction between reactants to form products.


The percent ionization of a 0.350 M HC,H,O2 solution. Ka(HC2H302)​

Answers

Answer:

The answer is 56

Explanation:

i need points

What is immigration and emigration

Answers

immigration is moving from current place to somewhere else whereaese emigration is reverse of it .

Answer:

well for me I think

Explanation:

immigration is the movement which involves an individual moving from a present place to another environment

That is going out

WHILE

Emigration is the process where a person comes into a particular environment

That means coming in

Calculate the energies of the n=2 and n=3 states of the hydrogen atom in Joules per
atom

Answers

Answer:

See Explanation

Explanation:

Positional Energy for electron as function of principle energy level (n)

=> Eₙ = -A/n²; A = 2.18x10⁻¹⁸J

Positional Energy for electron in n=2 => E₂ = -2.18x10⁻¹⁸/(2)² = -5.45x10⁻¹⁹J

Positional Energy for electron in n=3 => E₃ = -2.18x10⁻¹⁸/(3)² = -2.42x10⁻¹⁹J

ΔE(n=3→2) = -5.45x10⁻¹⁹J - (-2.42x10⁻¹⁹J) =   -3.03x10⁻¹⁹J

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