Calculate the pKa of lactic acid (CH3CH(OH)COOH) given the following information. 3.005 grams of potassium lactate are added to 100. mL of a 0.500 M lactic acid solution producing a pH of 3.526.

Answers

Answer 1

Answer:

[tex]\displaystyle \text{p} K_a \approx 3.856[/tex]

Explanation:

Because 3.005 grams of potassium lactate is added to 100. mL of solution, its concentration is:


[tex]\displaystyle \begin{aligned} \left[ \text{KC$_3$H_$_5$O$_3$}\right] & = \frac{3.005\text{ g KC$_3$H_$_5$O$_3$}}{100.\text{ mL}} \cdot \frac{1\text{ mol KC$_3$H_$_5$O$_3$}}{128.17 \text{ g KC$_3$H_$_5$O$_3$}} \cdot \frac{1000\text{ mL}}{1\text{ L}} \\ \\ &= 0.234\text{ M}\end{aligned}[/tex]

By solubility rules, potassium is completely soluble, so the compound will dissociate completely into potassium and lactate ions. Therefore, [KC₃H₅O₃] = [C₃H₅O₃⁺]. Note that lactate is the conjugate base of lactic acid.

Recall the Henderson-Hasselbalch equation:

[tex]\displaystyle \begin{aligned}\text{pH} = \text{p}K_a + \log \frac{\left[\text{Base}\right]}{\left[\text{Acid}\right]} \end{aligned}[/tex]

[Base] = 0.234 M and [Acid] = 0.500 M. We are given that the resulting pH is 3.526. Substitute and solve for pKₐ:

[tex]\displaystyle \begin{aligned} (3.526) & = \text{p}K_a + \log \frac{(0.234)}{(0.500)} \\ \\ 3.526 & = \text{p}K_a + (-0.330) \\ \\ \text{p}K_a & = 3.856\end{aligned}[/tex]

In conclusion, the pKₐ value of lactic acid is about 3.856.


Related Questions

Gas Law- please help!!!

In a mixture of carbon dioxide and oxygen, 40.0% of the gas pressure is exerted by oxygen. If the total pressure is 115 mmHg, what is the pressure of the carbon dioxide in
atm?

Answers

The pressure of the carbon dioxide will be 0.09079 atm.

What is partial pressure?

The pressure exerted by the individual gas is known as partial pressure.

The partial pressure is given as

[tex]\rm P_{Total} = P_1 + P_2 + ...[/tex]

In a mixture of carbon dioxide and oxygen, 40.0% of the gas pressure is exerted by oxygen.

If the total pressure is 115 mmHg.

The total pressure in atm will be

P = 115 mmHg

P = 0.15132 atm

We have

[tex]\rm P_T \ \ \ = P_{O_2} + P_{CO_2}\\\\0.15132 \ \ = 0.4 \times 0.15132 +P_{CO_2}\\\\ P_{CO_2} = 0.09079\ atm[/tex]

Then the pressure of the carbon dioxide will be 0.09079 atm.

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If you have 3 moles of gas at a pressure of 2.5 atmospheres and a volume of 8 liters, what is the temperature? Pay attention to the unit of pressure used.

A.) 81.27 K
B.) 0.81 K
C.) 57.86 K
D.) 25 K

Answers

The temperature of the gas would be 81.2 K

Ideal gas equation

The ideal gas equation is given by:

PV = nRT, where P, V, n, R, and T equals pressure, volume, number of moles, constant, and temperature respectively.

In this case, V = 8L, n = 3 moles, R = 8.317, and P = 2.5 atm or 253.3125 kpa

T = PV/nR = 253.3125 x 8/3 x 8.317 = 2026.5/24.951 = 81.2 K

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Why is it important to convert into units of kelvin before using the ideal gas law?.

Answers

It is important to convert into units of kelvin before using the ideal gas law because
Temperature is the denominator in the combined gas laws and can be derived in the idea gas law to the denominator.

A 10.00 g sample of wood from an archaeological site produced 3072 counts in a 10-hour measurement owing to the presence of carbon-14, while a 10.00 g sample of new wood produced 9216 counts in the same period of time. The half-life of carbon-14 is 5730 years. How old is the wood from the archaeological site

Answers

From the calculation, the age of the sample of carbon - 14 is 9156 years.

What is radioactivity?

The term radioactivity refers to the fact that a substance could disintegrate spontaneously when left alone.

Now, given that;

0.693/t1/2 = 2.303/t log (No/N)

t1/2 = half life

t = age of the sample

No = amount of sample originally present

N = amount of sample present at time t

Hence;

0.693/5730 =  2.303/t  log (9216/3072)

1.2 * 10^-4 =  2.303/t * 0.4771

1.2 * 10^-4 = 1.09876/t

t =  1.09876/1.2 * 10^-4

t = 9156 years

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Question 11
The modern periodic table is arranged by increasing atomic number of the elements.
O True
O False

Answers

Answer:

True

Explanation:

Answer:

Explanation:

Remark

It's true.

That's how the  periodic table is designed. Hydrogen is #1 and #116 is the latest entry. It is known as  flerovium and livermorium. I'm not sure if that and shouldn't be an or, but that is your answer.

What does Fe(NO3)2 + Cu stands for?​

Answers

Copper nitrate

Copper nitrate is the oxidizing agent as it gets reduced from +2 to 0 oxidization State and oxidize Fe from 0 to +2 state.

What is the molar mass of H₂CO₂?

Answers

Answer:

I think the Molar mass of H₂CO₂ should be 62..

Explanation:

I'm not too sure tho... Hope this helps!

Which reaction occurs at the anode in an electrochemical cell?
A. Zn(s) + Cu²+ (aq)
Zn²+ (aq) + Cu(s)
B. Zn(s) Zn²+ (aq) + 2e
C. Zn²+ (aq) + Cu(s)

Zn(s) + Cu²+ (aq)
OD. Zn²+ (aq) + 2e →
→ Zn(s)
SUBMIT

Answers

The reaction that occur at the anode of an electrochemical cell is Zn(s) Zn²+ (aq) + 2e. The correct option is B.

What is an electrochemoical cell?

An electrochemical cell has two eletcrodes present in an solution. The one electrode is anode where oxidation occurs and second is cathode hwere reduction occurs.

The reaction Zn(s) = Zn²+ (aq) + 2e due to oxidation chrage is added here.

Thus, the correct option is B. Zn(s) = Zn²+ (aq) + 2e.

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If the mass number of an atom is 29, and it has 13 protons and 13 electrons, what is the identity of this atom?

Answers

If the mass number of an atom is 29, and it has 13 protons and 13 electrons, the identity of this atom is Aluminum.

What is an atom?

An atom is the smallest indivisible particle of an element which still retains its chemical identity.

An atom consists of a nucleus surrounded by electrons. The nucleus is made up of protons and neutrons.

The identity of a chemical element is determined by its electron and proton number, which is the same for a neutral atom.

According to this question, the atom of an element has 13 protons and 13 electron. This suggests that the atom is that of Aluminum.

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A sample of gas occupies 300 mL at 100K. What is its volume when the
temperature is increased to 200K? (P and n= constant)

Answers

If the temperature of the sample of gas increases to the given value, the volume also increases to 600mL.

What is Charles's law?

Charles's law states that "the volume occupied by a definite quantity of gas is directly proportional to its absolute temperature.

It is expressed as;

V₁/T₁ = V₂/T₂

Given the data in the question;

Initial temperature of gas T₁ = 100KInitial volume of gas V₁ = 300mLFinal temperature T₂ = 200KFinal volume V₂ = ?

V₁/T₁ = V₂/T₂

V₂ = V₁T₂ / T₁

V₂ = ( 300mL × 200K ) / 100K

V₂ = 60000mLK / 100K

V₂ = 600mL

Therefore, if the temperature of the sample of gas increases to the given value, the volume also increases to 600mL.

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The rate law for the reaction 3a ⟶⟶ c is rate = 4. 36 x 10–2 l • mol–1 • h–1[ a ]2 how long will it take in hours for the concentration of a to decrease from 0. 74 m to 0. 21 m?

Answers

The hours taken for concentration to decrease from 0 to 74 min. to 0.21 m is 91.7 hours.

What is the rate law of a reaction?

Rate law depicts the rate of a chemical reaction depend on the concentration of the reactant.

The given reaction is second order reaction

Thus, the hours taken for concentration to decrease from 0 to 74 min. to 0.21 m is 91.7 hours.

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What causes atoms to form covalent bonds?

Answers

Answer:

to attain stability atoms form covalent bonds

ILL GIVE BRAINLY!!!!!!

How many different elements are involved in the reaction shown below?

CH4 + 2 O2 → CO2 + 2 H2O

Answers

Answer:

four

Explanation:

There is four

CH 4    methane

O2      oxygen

CO2    carbon dioxide

H20    water

Which statement best describes an advantage of describing a system with a mathematical model?

A.
It enables people to calculate how a change in one variable will affect other variables.
B.
It helps people visualize the way that systems are interconnected.
C.
It simplifies the system by describing only one variable at a time.
D.
It allows people to manipulate something that looks like the actual system.

Answers

An advantage of describing a system with a mathematical model is that it enables people to calculate how a change in one variable will affect other variables.

Describes an advantage of a system with a mathematical model?

A mathematical model usually describes a system by a set of variables and equations that formed relationships between the variables. Variables examples such as real or integer numbers.

So we can conclude that An advantage of describing a system with a mathematical model is that it enables people to calculate how a change in one variable will affect other variables.

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Among K, Ca and Ba, which element possess low ionization energy?

Answers

Among the elements Barium has the lowest Ionization Energy.

What is Ionization Process ?

The process by which any neutral atom gets converted into electrically charged by gaining or losing electron is called Ionization Process.

K  is an alkali metal  it has to lose one electron to attain stable electronic configuration of an inert gas

For removing second electron , a stable configuration has to be broken and so will require high amount of energy.

Ca and Ba are alkaline earth metals.

They both have to lose 2 electrons to attain  stable electronic configuration of noble gas.

They have low Iow Ionization Energy as compared to K.

Ca has higher  Ionization Energy as compared to Ba because when we move down the periodic table , The ionization energy decreases.

Hence , Among the elements Barium has the lowest Ionization Energy.

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Lab: Applications of electromagnetic​
Instructions
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Your work will not be submitted to your teacher until you click Submit.

Documents
Student Guide - Electromagnets project

Answers

Answer:Not the same class but it will give u 100%

Explanation:

1. This experiment was to find how mass and speed effect KE. This is important because if you were in a situation where you needed something to go higher, you would know to add more or less of mass/speed.  

To test mass, we filled the bean bag with a certain amount of water, then dropped it. After, you recorded how high it made the bean bag go. The same with speed, but same amount in the bottle, just dropped from different heights.  

My hypothesis is when you have more mass, the KE will be greater. This is also the same with speed, if it is dropped from a higher place, the bean bag will launch farther than the last time.  

2. Data I collected from the lab was like my hypothesis explained. When the height of the bottle increased, it made the bean bag go higher than the last. And I tested 4 different masses, 0.125 kg, 0.250kg, 0.375kg and 0.500kg. Each time the bean bag went higher on a larger mass.  

A lot of times on the speed test, the bean bag would go higher than the bottle drop point, but not every time. Also, when it was dropped from the same height each time, some results varied quite a bit, like when it was dropped from 1.28 the results were 1.14 then 1.30 1.30. Mass on the other hand was all in the same number range, only once the numbers were a bit off from each other.  

3.  Some formulas I used were KE= ½ mv^2 and Ht v^2/2g. The first was to calculate the kinetic energy of an object, m=mass v=speed. Second was for finding out what height I needed to drop something to reach a certain speed, Ht=Height and g= Gravitational Acceleration of 9.8 m/s^2.  

I used these to figure out tables that showed relationships between different things like mass and KE or speed and height. The whole time I was doing the lab, my data was going up, when there was more mass/speed there were higher values in the table.  

This means that my hypothesis at the beginning was correct, more of m/s means KE will increase proportionally because they are all linear. I found it surprising when the bean bag height went over the water bottle drop mark.  

4.     To conclude, my hypothesis matched my data. The data values went up when more mass or speed was added. This means if I were in a situation where I needed more kinetic energy for something, I would know to increase mass or the speed of the object giving it energy.  

The reason that this hypothesis is correct is when you have more mass, you have more energy. So, when you drop let's say a baseball, it isn’t that heavy so it would only launch the bean bag so far. But a bowling ball is very heavy and has lots of energy when falling because of that, it would make the bean bag go very high.  

To make this experiment better, I would use a smoother material for the lever so energy wouldn’t be lost by friction from wood rubbing together. Also, maybe a scanner or video camera to more accurately record how far the bean bag went. All of these would help the lab get more precise results, maybe they could be used in a future lab.

what is the specific heat capacity of propan-1-ol​

Answers

Answer:

11–350°

Explanation:

please help meeeeeeeee​

Answers

Number one is the balanced equation because both sides have 1 Ca 1 C and 3 Os

3.

Explanation:

all Chemical mixtures have the same amount of numbers making them all balanced.

(that's the simple way of putting it, but hoped it helped ✌)

A base is a substance that can __________ a hydroxide ion.

Answers

Answer:

An Arrhenius base is a substance that dissociates in water to form hydroxide (OH–) ions. In other words, a base increases the concentration of OH– ions in an aqueous solution.


calculate the molarity of 65.3 grams of sugar(342.3 g/mol), c12h22011 in 750 ml of solution.

Answers

Answer:

0.254 M

Explanation:

If the formula mass of sugar is 342.3 g/mol, and there are 65.3 g, then there are 65.3/342.3=0.190768 mol.

Also, 750 mL = 0.750 L.

molarity = (moles of solute)/(liters of solution)

molarity = 0.190768/0.750 = 0.254 M

if this strand is replicated what is the complementary strand that is produced

Answers

Answer:

During DNA replication, each of the two strands that make up the double helix serves as a template from which new strands are copied. The new strand will be complementary to the parental or “old” strand. Each new double strand consists of one parental strand and one new daughter strand.

Explanation:

hope it helps you

As you move upward, from level, in an energy pyramid, available energy ____.

1. is destroyed

2. decreases

3. stays the same

4. increases

Answers

The available energy decreases as one moves upward in an energy pyramid.

Energy pyramid

The energy pyramid represents a model of how energy is transferred from one trophic level to another in ecosystems.

Energy is transferred from producers to primary consumers, from primary to secondary consumers, from secondary to tertiary consumers, and so on.

Only about 10% of the available energy in one trophic level is transferred to the next with the remaining 90% being lost as heat to the environment.

Thus, as one moves up the energy pyramid, the available energy decreases. This is why organisms at the higher end of the energy pyramid have to devise an efficient way of extracting energy from their foods.

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The total mass of the reactants is equal to the total mass of products. this is known as the conservation of what?

Answers

Explanation:

the law of conservation of mass

Answer:

Explanation:

the law of conservation of mass

At what temperature would 0.46 moles of a gas occupy 13.3 L if the pressure is 734 mm Hg?

Answers

Answer: 339.84 K

Explanation:

[tex]$$We are given: \\$\mathrm{n}=0.46$ moles \\$V=13.3 \mathrm{~L}$\\$\mathrm{P}=734 \mathrm{~mm} \mathrm{Hg}=0.965 \mathrm{~atm}$\\Putting these values in ideal gas equation we get:\\$0.965$ batm * $13.3 \mathrm{~L}=0.46 \mathrm{~mol} * 0.0821 \frac{\mathrm{atmL}}{\mathrm{molK}} * \mathrm{~T}$\\$\mathrm{T}=\frac{0.965 * 13.3}{0.46 * 0.0821} \mathrm{~K}$$$\mathrm{T}=339.84 \mathrm{~K}$$[/tex]

If you add sucrose to catalase when testing for reactivity, do you expect to see a reaction?.

Answers

There is no reaction when you add catalase to sucrose.

What is sucrose?

Sucrose is a disaccharide that consist of glucose and fructose. Both glucose and fructose are hexoses.

Owing to the fact that catalase is specific to sucrose, there is no reaction when you add catalase to sucrose.

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Toothpaste contains Sodium fluoride which is used to prevent tooth decay. How many grams are in 1 mole NaF?

Answers

Answer:

0.24%

Explanation:

A toothpaste contains 0.24% by mass sodium fluoride (NaF) used to prevent dental caries and 0.30% by mass triclosan, C12H7Cl3O2, a preservative and antigingivitis agent. One tube contains 119 g of toothpaste. (6.4, 6.5) Components in toothpaste include triclosan and NaF.a. How many moles of NaF are in the tube of toothpaste?b. How many fluoride ions (F?) are in the tube of toothpaste?c. How many grams of sodium ion (Na+) are in 1.50 g of toothpaste?d. How many molecules of triclosan are in the tube of toothpaste?Solution 124CQStep 1 of 4:Given:Mass of toothpaste = 119 g. Mass percent of sodium fluoride (NaF) = 0.24%Mass percent of triclosan (C12H7Cl3O2) = 0.30%a. Here, we are asked to find the number of moles of NaF in the tube of toothpaste.Mass percent of sodium fluoride (NaF) = 0.24%First, let’s find the mass of NaF in the tube: = 119 g = 0.2856 grams Molar mass of NaF = 41.98 g/mol This means, 1 mol NaF = 41.98 g. So, the mole-mass factor is: and Therefore, number of moles of NaF will be: = 0.2856 g NaF = 0.00680 mol NaFHence, the number of moles of NaF in 119g toothpaste is 0.00680 moles. ________________

According to mole concept, there are 41.988 grams   in 1 mole NaF that is sodium fluoride.

What is a mole?

Mole is defined as the unit of amount of substance . It is the quantity measure of amount of substance of how many elementary particles are present in a given substance.

It is defined as exactly 6.022×10²³ elementary entities. The elementary entity can be a molecule, atom ion depending on the type of substance. Amount of elementary entities in a mole is called as Avogadro's number.

It is widely used in chemistry as a suitable way for expressing amounts of reactants and products.For the practical purposes, mass of one mole of compound in grams is approximately equal to mass of one molecule of compound measured in Daltons. Molar mass has units of gram per mole . In case of molecules, where molar mass  in grams present in one mole  of atoms is its atomic mass.

Number of moles is given by the formula, mass/molar mass and hence mass= 1×41.988= 41.988 g.

Thus, there are 41.988 g in 1 mole NaF.

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One atom of lithium, Li, reacts with fluorine, F, to produce lithium fluoride, LiF2. The atomic mass of lithium is 7 amu. The mass of one atom of lithium fluoride is 45 amu. Which statement about the reaction is correct?

Answers

Lithium reacts with one atom of fluorine, and the atomic mass of fluorine is 38 amu.

What is atomic mass?

The atomic mass of an element is the average mass of the atoms of an element measured in atomic mass unit.

One lithium (Li) atom can combine with one fluorine (F) atom. Together, they make the formula LiF.

Fluorine has seven electrons of it's own. Lithium gives up its one electron to make both atoms happy.

Hence, lithium reacts with one atom of fluorine, and the atomic mass of fluorine is 38 amu.

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Bromine has two naturally occurring isotopes (br-79 and br-81) and has an atomic mass of
79.904 amu. the mass of br-81 is 80.9163 amu, and its natural abundance is 49.310%. what is
the mass of br-79?

Answers

Answer: 78.919 amu

Explanation:

If the natural abundance of Br-81 is 49.310%, then the natural abundance of Br-79 must be 100%-49.310%=50.690%

Substituting into the atomic mass formula,

[tex]79.904=(0.49310)(80.9163)+(0.50690)(x)\\79.904=39.89982753+(0.50690)(x)\\40.00417247=(0.50690)(x)\\x=\frac{40.00417247}{0.50690}=\boxed{78.919 \text{ amu}}[/tex]

Organic compounds differ from inorganic compounds in that organic compounds generally have.

Answers

Answer:

carbon and hydrogen atoms

Does anyone know what 5.7365 x 10^-5 + 3.4891 x 10^-8 is? in scientific notation preferably?

Answers

Answer:

5.7400 × 10⁻⁵

Explanation:

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