Answers
Answer:
HEPES.
Explanation:
Hello,
In this case, considering the given options, and the pH requirement of 7.5, considering the Henderson-Hasselbach equation:
[tex]pH=pKa+log(\frac{[base]}{[acid]})[/tex]
The best buffer is that having the closest pKa to the required pH, thus, for the given Ka, we obtain:
[tex]pKa_{MES}=-log(Ka_{MES})=-log(7.9x10^{-7})=6.10\\\\pKa_{HEPES}=-log(Ka_{HEPES})=-log(3.2x10^{-8})=7.49\\\\pKa_{Formic \ acid}=-log(Ka_{Formic \ acid})=-log(1.8x10^{-4})=3.74\\\\pKa_{Acetic\ acid}=-log(Ka_{Acetic\ acid})=-log(1.8x10^{-5})=4.74\\\\pKa_{Tris}=-log(Ka_{Tris})=-log(6.3x10^{-9})=8.2[/tex]
Therefore, the best buffer is the HEPES since its pKa is almost the required pH.
Regards-
Related Questions
A farmer applies 1455 kg of a fertilizer that contains 10.0% nitrogen to his fields each year. Fifteen percent (15.0%) of the fertilizer washes into a river that runs through the farm.If the river flows at an average rate of 0.175 cubic feet per second, what is the additional concentration of nitrogen (expressed in milligrams of nitrogen per liter) in the river water due to the farmer's fertilizer each year?
Answers
Answer:
the additional concentration of nitrogen in the water = 0.1396 mg/L
Explanation:
Given that a farmer uses 1455 kg of fertilizer → 10% nitrogen
15% of the fertilizer is said to be washed into the river,
i.e.
(15/100) × 1455 = 218.25 kg
The amount of nitrogen molecule in the washed fertilizer is :
10% of 218.25 kg
= (10/100) × 218.25 kg
= 0.1 × 218.25 kg
= 21.825 kg in a year.
The river flows at an avg. rate of 0.175 ft³/sec
Then the amount of river water in a year = [tex]0.175 \dfrac{ft^3}{sec}\times 3.155 \times 10^7 \ sec[/tex]
since 1 ft³ = 28.3168 L
the amount of river water in a year = [tex]0.175(28.3168)\times 3.155 \times 10^7 \ L[/tex]
the amount of river water in a year = 156344132
The concentration of nitrogen molecule= mass/volume
= [tex]\dfrac{ 21.825 \times 10^6 \ mg}{ 156344132 \ \ L }[/tex]
= 0.1396 mg/L
Thus, the additional concentration of nitrogen in the water = 0.1396 mg/L
What is most likely to occur when jagged edges of rock plates grind past each other?
Answers
Answer:
The most likely to occur when jagged edges of rock plates grind past each other is the presence of a high degree of frictional force.
This may cause the rocks to be broken down into smaller particles.
It also implies that the energy necessary for further disintegration and movement of rocks is stored up.
Which statements are true about triangle ABC and it’s translated image, ABC? Select two options.
Answers
Which phrase is evidence of the limits of what science can study?
Answers
This question is incomplete; here is the complete question:
Which phrase is evidence of the limits of what science can study?
A. Only a phenomenon that a scientist can observe with instruments
B. Only a phenomenon that a scientist can observe without instruments
C. Only a phenomenon that a scientist will be able to explain with certainty
D. Any phenomenon that a scientist can observe or model
The correct answer is D. Any phenomenon that a scientist can observe or model
Explanation:
Science focuses on phenomena that can be objectively studied or witnessed. This includes any phenomenon a scientist can register using observation, instruments, or that can be represented through models. This is because, through observations or instruments, it is possible to prove the phenomenon occurs and understand how this happens; also, models can represent or recreate the phenomenon itself, which is essential to understand and explain the phenomenon. Moreover, science has an objective focus and due to this, aspects such as personal beliefs that cannot be represented through a model or be observed are not part of science. According to this, the correct answer is D.
[H+] for a solution is 4.59 x 10-6 M.
This solution is
A. acidic
B. basic
C. neutral
Answers
Answer:
A. acidic
Explanation:
Answer:
acidic
Explanation:
. Answer the following: 7 x 2 = 14
1. Find
1. Find
2/3÷4
Answers
Explanation:
2/3 ÷ 4 = 0.166
I think this should be the answer
Explanation:
[tex] \frac{2}{3} \div 4[/tex]
[tex]make \: 4 \: as \: \frac{1}{4} \: since \: is \: divide[/tex]
[tex] \frac{2}{3} \times \frac{1}{4} [/tex]
[tex] \frac{2}{12} = \frac{1}{6} [/tex]
Hope this is correct and helpful
HAVE A GOOD DAY!
Which of the following solutions is basic?a. [H3O+] = 1.0 x 10-10 Mb. [OH-] = 1.0 x 10-10 Mc. [H3O+] > 1.0 x 10-7 Md. [OH-] < 1.0 x 10-10 Me. [OH-] = 1.0 x 10-7 M
Answers
Answer:
[H3O+] = 1.0 x 10-10
Explanation:
A basic solution is any solution whose pH is above 7.0.
If we carefully calculate the pH of each of the species listed among the options, we will discover that it is only [H3O+] = 1.0 x 10-10 that has a pH of 10.0. This pH corresponds to a basic solution. Hence the solution having [H3O+] = 1.0 x 10-10 is a basic solution.
unit processes in charge of smelting
Answers
Answer:
Smelting, process by which a metal is obtained, either as the element or as a simple compound, from its ore by heating beyond the melting point, ordinarily in the presence of oxidizing agents, such as air, or reducing agents, such as coke.
Hope I helped!
Explanation:
why do scientists store oxygen and hydrogen in water?
Answers
Answer:
When molecular hydrogen (H2) and oxygen (O2) are combined and allowed to react together, energy is released and the molecules of hydrogen and oxygen can combine to form either water or hydrogen peroxide. ... For both of the reactions shown, the hydrogen molecules are oxidized and the oxygen atoms are reduced.
Explanation:
Find the density of an empty tissue box with a mass of 345 grams and a volume of 1125 cm3.
Answers
Answer:
The answer is
0.307 g/cm³Explanation:
The density of a substance can be found by using the formula
[tex]density = \frac{mass}{volume} [/tex]
From the question
mass of box is 345 g
volume = 1125 cm³
The density of the object is
[tex]density = \frac{345}{1125} \\ = 0.3066666...[/tex]
We have the final answer as
0.307 g/cm³Hope this helps you
Which element is the
most reactive?
A . Silicon
B. oxygen
C. lithium
D . Aluminum
Answers
Which of the following species is the least nucleophilic?A) (CH3)3NB) BF3C) H2OD) (CH3)3CO-E) CN-
Answers
Answer:
BF3
Explanation:
BF3 possesses an open sextet. This implies that the octet around the central atom is incomplete. As a result of this, BF3 will function as an electrophile rather than as a nucleophile.
Hence of all the compounds listed in the options, BF3 is the least nucleophillic.
Why do astronauts with less on the moon than they do on Earth
Answers
If the atom has a MASS of 127 and 45 NEUTRONS, then it contains how many
PROTONS

Answers
Answer:
53
Explanation:
because minus 3
What is the density of an unknown metal that has a mass of 157.4 g and a volume of 20 mL?
Answers
Answer:
7.87g/mL
Explanation:
density=mass/volume
density=157.4/20
density=7.87g/mL
HURRY PLEASE! True or false: Making an observation is the first step of the scientific method.
Answers
Answer:
True
Explanation:
You must first observe your data then form a hypothesis.
PLEASE HELP WILL MARK BRAINLIEST!!!!!!!!
Answers
Explanation:
1. 4×10^5
2. 6×10^-4
3. 2.1995×10^7
4. 5.050×10^-2
5. 7280
6. 0.00003608
7. 940.9
8. 0.0015
Marks as brainest
Answer:
not sure
Explanation:
general characteristics of coinage metals
Answers
Answer:
Characteristics. They are all relatively inert, corrosion-resistant metals. Copper and gold are colored. These elements have low electrical resistivity so they are used for wiring.
Explanation:
Hope this help u
️️
My barometer is reading 1253 torr. What is the pressure in mmHg?
A. 1.253
B. 1.649
C. 1253
D. 1649
Answers
Answer:
The pressure in mmHg is 1253 (option C)
Explanation:
Two quantities are directly proportional if when multiplying or dividing one of them by a number, the other is multiplied or divided by that number. In other words, the magnitudes are directly proportional when one magnitude increases and so does the other in the same proportion; or when one magnitude decreases and so does the other in the same proportion.
The rule of three or is a way of solving proportionality problems between three known values and an unknown value, which can be applied to directly proportional quantities as follows:
a ⇒ b
c ⇒ x
So [tex]x=\frac{c*b}{a}[/tex]
where a, b and c are data and x is the unknown value to be calculated.
In this case, knowing that 1 Torr = 1 mmHg, the rule of three can be applied as follows: if 1 torr is equal to 1 mmHg, 1253 torr is equal to how many mmHg?
[tex]pressure=\frac{1253 torr*1 mmHg}{1 torr}[/tex]
pressure= 1253 mmHg
The pressure in mmHg is 1253 (option C)
the simplest formula for a compound made from element X(molar mass=79.0g mol) that is 21.0% nitrogen by mass is ___
A. XN
B. XN2
C.X2N2
D.X3N2
Answers
Answer:
C
Explanation:
Compounds are substances that are made of elements linked by chemical bonds. "The simplest formula for a compound made from element X that is 21.0% nitrogen by mass is X₂N₃." Thus, option C is correct.
What is the empirical formula?The empirical formula has been the representation of the ratio of the whole number of atoms involved to make a molecule or compound. It has been calculated by calculating the moles through mass and, molar mass.
The elements involved are X (unknown), and N (known).
Given,
Mass percentage of nitrogen = 21.0% = 21 gms
Mass percentage of X = 100.0 % - 21.0 % = 79.0% = 79 gms
Molar mass of X = 79.0 g /mol
Molar mass of Nitrogen = 14 g/mol
Moles of X is calculated as:
Moles X = 79 ÷ 79
= 1 mol
Moles of N are calculated as:
Moles N = 21 ÷ 14
= 1.5 mol
Now, the moles are divided by the smallest mole as:
X = 1 ÷ 1 = 1
N = 1.5 ÷ 1 = 1.5
The ratios are 1:1.5 or 2:3. 2X and 3N.
The empirical formula for the compound will be X₂N₃.
Therefore, the simplest formula for the compound will be X₂N₃.
Learn more about empirical formula, here:
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Consider the fructose-1,6-bisphosphatase reaction. Calculate the free energy change if the ratio of the concentrations of the products to the concentrations of the reactants is 21.321.3 and the temperature is 37.0°C37.0°C ? ΔG°′ΔG°′ for the reaction is −16.7 kJ/mol−16.7 kJ/mol .
Answers
Answer:
ΔG = -8.812 kJ/mol
Explanation:
To obtain the free energy of a reaction you can use the expression:
ΔG = ΔG° + RT ln Q
Where:
ΔG° is Standard Gibbs Free energy: -16.7kJ/mol = -16700J/mol
R is gas constant: 8.314472 J/molK
T is absolute temperature (37°C + 273.15 = 310.15K)
And Q is reaction quotient: 21.3
Replacing in the formula:
ΔG = ΔG° + RT ln Q
ΔG = -16700J/mol + 8.314472J/molK*310.15K ln 21.3
ΔG = -8812.4J/mol
ΔG = -8.812 kJ/mol
Question 3 of 10
Which of the following is an example of a phase change from liquid to solid?
A. Ice melting
B. Water freezing
C. Water evaporating
D. Water condensing
Answers
Answer:
the answer is B
Explanation:
B is the answer
how many cg are equal to 0.459kg
Answers
1kg = 100000
0.459kg = 0.459*100000
= 45900cg
→ 0.459kg = 45900cg
According to unit conversion and as 1 kg=100,000 cg , there are 45900 cg in 0.459 kg.
What is unit conversion?Unit conversion is defined as a multi-step process which involves multiplication or a division operation by a numerical factor.The process of unit conversion requires selection of appropriate number of significant figures and the rounding off procedure.
It involves a conversion factor which is an expression for expressing the relationship between the two units.A conversion ratio always has value which equals to one which indicates that numerator and denominator have values which are expressed in different units.
It is an easy process which involves unit conversion between the different conversion systems. While unit conversion care needs to be taken regarding accuracy and precision.
Learn more about unit conversion,here:
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Select the numbers that show how the numbers given in scientific notation can be added. 2.00 times 10 to the negative 26th power minus 3.34 time 10 to the negative 27th power. Below that, a math example: 2.00 x 10 to the negative 26th power minus A time 10 to the B power equals C times 10 to the D power. A = B = C = D =
Answers
Answer:
A = 0.334
B = -26
C = 1.666
D = -26
Explanation:
just took quiz
Answer:
A = ✔ 0.334
B = ✔ -26
C = ✔ 1.666
D = ✔ -26
Explanation:
edge 2023
Determine which physical conditions are necessary to support nuclear fusion and formation of stars.
Answers
Answer:
The correct approach will be "Increased gravitational attraction".
Explanation:
The increased gravitational attraction seems to be the natural or physical phenomenon that is required to promote nuclear reactions including star formation. This is much more important to establish stars at different temperatures (lower) and greater magnetic pull as well as nuclear fusion tends to happen.help me ill give brainliest i need help with a b c d and to see if i got propene and methane right please help :(
Answers
Answer:Yes, you got it right
Explanation:
Pls give brainliest
what is the molar mass of PbCO₄
Answers
Answer:
283.211
Explanation:
An automobile tire contains air at 320.×103 Pa at 20.0 ◦C. The stem valve is removed and the air is allowed to expand adiabatically against the constant external pressure of 100.×103 Pa until P = Pexternal. Assume the air is an ideal gas with C¯ V = 5/2 R (diatomic). Calculate the final temperature.
Answers
Answer:
6.15.3 k
Explanation:
From the question we can see that
q = 0, Δu = w
Then,
[tex]T_f = \frac{C_{V,m}+RP_{ext}P_i}{C_{V,m}+RP_{ext}P_f} T_i[/tex]
putting values wet
=[tex]\frac{2.5\times 8.314+8.314\left(10^5\right)\left(3.20\times 10^5\right)}{2.5\times 8.314+\left(8.314\right)\left(10^5\right)\left(10^5\right)}\times \:293[/tex]
T_f = 615.3 K
Which one correctly lists the compound that has the highest boiling point from each group it belongs to? Group I: SiH 4, SnH 4, CH 4, and GeH 4 Group II: HCl, HBr, HF, and HI Group I: SiH4 and Group II: HF Group I: SnH4 and Group II: HF Group I: SnH4 and Group II: HI Group I: CH4 and Group II: HI Group I: CH4 and Group II: HF
Answers
Answer:
Group I: SnH4 and Group II: HF
Explanation:
In the case of group 14 hydrides, we know that the melting and boiling points of compounds increase down the group. Since the melting and boiling points of compounds increase down the group, SnH4 will have the highest boiling point.
In the case of group 17 hydrides, we know that electro negativity decreases down the group. As electro negativity decreases, so does the magnitude of hydrogen bonding among group 17 hydrides. Hence, HF has the highest boiling point among group 17 hydrides since it has the greatest magnitude of hydrogen bonding between its molecules.
Strontium-90 is radioactive and has a half life of 28.8 years. How much of a 2.90mg sample would be left after 137. years?
Round your answer to 2 significant digits. Also, be sure your answer has a unit symbol.
Answers
Answer:
0.11 mg
Explanation:
From the question given above, the following were obtained:
Half life (t½) = 28.8 years
Original amount ((N₀) = 2.90 mg
Time (t) = 137 years
Amount remaining (N) =?
Next, we shall determine the rate of disintegration (K). This can be obtained as follow:
Rate of decay (K) = 0.693/ half life (t½)
K = 0.693 / t½
Half life (t½) = 28.8 years
Rate of decay (K) =?
K = 0.693 / t½
K = 0.693 / 28.8
K = 0.0241 /year
Finally, we shall determine amount remaining after 137 years as follow:
Original amount ((N₀) = 2.90 mg
Time (t) = 137 years
Rate of decay (K) = 0.0241 /year
Amount remaining (N) =?
Log (N₀/N) = kt/2.3
Log (2.9/N) = 0.0241 × 137 / 2.3
Log (2.9/N) = 3.3017 / 2.3
Log (2.9/N) = 1.4355
Take the antilog of 1.4355
2.9/N = antilog (1.4355)
2.9/N = 27.26
Cross multiply
2.9 = N × 27.26
Divide both side by 27.26
N = 2.9/27.26
N = 0.11 mg
Therefore, the amount remaining after 137 years is 0.11 mg
