CHEMISTRY HIGH SCHOOL

A new potential heart medicine, code-named X-281, is being tested by a pharmaceutical company, Pharma-pill. As a research technician at Pharma-pill, you are told that X-281 is a monoprotic weak acid, but because of security concerns, the actual chemical formula must remain top secret. The company is interested in the drug's Ka value because only the dissociated form of the chemical is active in preventing cholesterol buildup in arteries.To find the pKa of X-281, you prepare a 0.089 M test solution of X-281 at 25.0 ∘C. The pH of the solution is determined to be 2.40.
a. What is the pKa of X-281? Express your answer numerically.
At 25∘C, for any conjugate acid-base pair
pKa + pKb = 14.00
b. What is pKb of the conjugate base of X-281? (Assume 25 ∘C.) Express your answer numerically.

Answers

Answer 1

Answer:

Answer:

a. pka = 3,73.

b. pkb = 10,27.

Explanation:

a. Supposing the chemical formula of X-281 is HX, the dissociation in water is:

HX + H₂O ⇄ H₃O⁺ + X⁻

Where ka is defined as:

$ka = ([H_3O^+][X^-])/([HX])$

In equilibrium, molar concentrations are:

[HX] = 0,089M - x

[H₃O⁺] = x

[X⁻] = x

pH is defined as -log[H₃O⁺]], thus, [H₃O⁺] is:

$[H_3O^+]} = 10^(-2,40)$

[H₃O⁺] = 0,004M

Thus:

[X⁻] = 0,004M

And:

[HX] = 0,089M - 0,004M = 0,085M

$ka = ([0,004][0,004])/([0,085])$

ka = 1,88x10⁻⁴

And pka = 3,73

b. As pka + pkb = 14,00

pkb = 14,00 - 3,73

pkb = 10,27

I hope it helps!

Related Questions

Gold has a density of 19.3 g/cm3. What is the mass, in kilograms, of one cubic meter of gold?
How do you find the name of the chemical formula Pb3N4 (the 3 and 4 are subscripts)
Near the surface of a liquid, fast-moving particles can break free and become a gas. a. True b. False
A certain reaction has an activation energy of 66.41 kJ/mol. At what Kelvin temperature will the reaction proceed 3.00 times faster than it did at 293 K?
If you travel from the Earth to the moon, which of the following measurements would change? Mass Weight Density Size

Simple chem question - please help!Given the equation: N2 +2O2 → 2NO2, what mass of oxygen is required to react completely with 7g of nitrogen?

A) 8 g
B) 16 g
C) 32 g
D) 64 g

Answers

Molar mass O₂ = 32.0 g/mol and N₂ = 28.0 g/mol

N₂ +2 O₂ → 2 NO₂

28.0 g -------> 32.0 * 2
7 g ----------> ?

Mass of O₂ = 7 * 32.0 * 2 / 28.0

Mass of O₂ = 448 / 28.0

= 16 g of O₂

Answer B

hope this helps!

Answer:

guy above is right

Explanation:

The muscles in your body make up about percent of your body weight.

Answers

The muscles in our body make up for 38% - 54% in males and 28% - 39% in females.

Answer:

The answer is 40-50 percent I did it and it was correct.

Explanation:

I would not mind Brainliest pls.

A.) Thermal Decomposition of 2.765 g NaHCO3 yields 1.234g of a solid Na2CO3 . Calculate the theoreticial yield and percent yield of Na2CO3.B) Thermal decomposition of 2.968 g of a mixture containing NaHCO3 lost 0.453 g . Calculate the percentage of NaHCO3 in this unknown mixture

Answers

Answer:

For A: The percent yield of sodium carbonate is 70.5 %

For B: The percent of sodium hydrogen carbonate in the unknown mixture is 15.26 %

Explanation:

For A:

To calculate the number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$ .....(1)

Given mass of sodium hydrogen carbonate = 2.765 g

Molar mass of sodium hydrogen carbonate = 84 g/mol

Putting values in equation 1, we get:

$\text{Moles of sodium hydrogen carbonate}=(2.765g)/(84g/mol)=0.033mol$

The chemical equation for the thermal decomposition of sodium hydrogen carbonate follows:

$2NaHCO_3(s)\rightarrow Na_2CO_3(s)+CO_2(g)+H_2O(g)$

By Stoichiometry of the reaction:

2 moles of sodium hydrogen carbonate produces 1 mole of sodium carbonate

So, 0.033 moles of sodium hydrogen carbonate will produce = $(1)/(2)* 0.033=0.0165mol$ of sodium carbonate

Now, calculating the mass of sodium carbonate from equation 1, we get:

Molar mass of sodium carbonate = 106 g/mol

Moles of sodium carbonate = 0.0165 moles

Putting values in equation 1, we get:

$0.0165mol=\frac{\text{Mass of sodium carbonate}}{106g/mol}\n\n\text{Mass of sodium carbonate}=(0.0165mol* 106g/mol)=1.75g$

To calculate the percentage yield of sodium carbonate, we use the equation:

$\%\text{ yield}=\frac{\text{Experimental yield}}{\text{Theoretical yield}}* 100$

Experimental yield of sodium carbonate = 1.234 g

Theoretical yield of sodium carbonate = 1.75 g

Putting values in above equation, we get:

$\%\text{ yield of sodium carbonate}=(1.234g)/(1.75g)* 100\n\n\% \text{yield of sodium carbonate}=70.5\%$

Hence, the percent yield of sodium carbonate is 70.5 %

For B:

To calculate the percentage composition of sodium hydrogen carbonate in mixture, we use the equation:

$\%\text{ composition of sodium hydrogen carbonate}=\frac{\text{Mass of sodium hydrogen carbonate}}{\text{Mass of mixture}}* 100$

Mass of mixture = 2.968 g

Mass of sodium hydrogen carbonate = 0.453 g

Putting values in above equation, we get:

$\%\text{ composition of sodium hydrogen carbonate}=(0.453g)/(2.968g)* 100=15.26\%$

Hence, the percent of sodium hydrogen carbonate in the unknown mixture is 15.26 %

2NaHCO3 -> Na2CO3 + H2O + CO2
2.765g NaHCO3/MM = moles NaHCO3
moles NaHCO3 x (1 mole Na2CO3 / 2 moles NaHCO3) x MM Na2CO3 = theoretical yield of Na2CO3

Percent yield is simply the actual yield/theoretical yield (x100 to put it into percentage).

MM = Molar mass (grams of substance per mol)

Compounds have similar properties to the elements of which they are made.For example, FeS is magnetic and smelly, since iron (Fe) and sulfur (S) are attracted to a magnet, and possess an odor of eggs,
respectively

True
False

Answers

Answer:

false

Explanation:

The properties of compounds are often very different from the properties of the elements that make them. For example, water is made from two atoms of hydrogen bonded to one atom of oxygen. ... The elements calcium and chlorine combine to form the compound calcium chloride. Calcium is a soft, silvery metallic solid.

Answer:

the answer is False

Explanation:

False

Hope this helps

Please help :)1: Catalysts lower the activation energy of chemical reactions. How does this benefit the environment?

2: Chlorine free radicals are produced in the upper atmosphere when ultraviolet radiation interacts with chlorofluorocarbons (CHCs). The free radicals catalyze the conversion of ozone to oxygen. How is this catalysis harmful to humans

Answers

1. By using less energy, reactions that are catalysed are also more sustainable, and therefore better for the environment.

2. By catalysing the conversion of ozone into oxygen, the ozone layer sees a reduction, also reducing the amount of protection from direct UV rays given to humans and other forms of life by the ozone layer.

As the air temperature increases, with no addition of water vapor to the air, the dew point will ____. a. remain the same b. increase c. decrease d. become equal to the air temperature

Answers

Answer:

Option (A)

Explanation:

A dew point is usually defined as the specific temperature at which the air gets cooled in order to undergo complete saturation with water vapor. This refers to the condition when the relative humidity becomes 100%, and with progressive cooling, it results in the process of condensation, thereby giving rise to the formation of dew.

In a condition, where there is increasing air temperature and no addition of water vapor, the dew point will eventually remain the same. It is because there is not enough water vapor present in the air for the condensation process to take place and form dew.

Thus, the correct answer is option (A).

Final answer:

The dew point would remain the same when air temperature increases without any additional water vapor. The dew point is dependent on humidity and not on the air temperature. Hence, increase in air temperature with no extra water vapor will leave the dew point unchanged.

Explanation:

Dew Point and Air Temperature

The dew point is the temperature at which air becomes saturated with water vapor after cooling without changing its pressure or moisture content. It's significant in understanding weather and climate patterns. If the air temperature increases with no additional water vapor introduced to it, the dew point would remain the same.

This is because the dew point depends on the humidity or water vapor content of the air, not the air temperature. Thus, without the addition of more water vapor, the amount of water the air can hold at saturation stays the same, therefore the dew point remains the same.

Learn more about Dew Point here:

brainly.com/question/33345309

#SPJ3

Other Questions

Calculate the amount of energy released in the formation of one mole of BaSe bonds (not lattice energy). The radius of the barium ion is 1.35 Å, and the radius of the selenide ion is 1.98 Å. Note that 1Å=10−10m.

Does a solution have to involve a liquid? Explain your answer

Which is true about the dissolving process in water?

The pH of a .1 M solution is 11. What is the concentration of H3O ions, in miles per liter