Answer:
Formic acid and Acetic acid is the best buffer at pH 3.7.
Explanation:
Given that,
The Ka values for several weak acids are given,
[tex]K_{a}\ of\ MES=7.9\times10^{-7}[/tex]
[tex]K_{a}\ of\ HEPES = 3.2\times10^{-3}[/tex]
[tex]K_{a}\ of\ Tris=6.3\times10^{-9}[/tex]
[tex]K_{a}\ of\ formic\ acid = 1.8\times10^{-4}[/tex]
[tex]K_{a}\ of\ Acetic\ acid = 1.8\times10^{-5}[/tex]
We need to calculate the pH of the weak acids with their [tex]pK_{a}[/tex] values
Using formula of [tex]pK_{a}[/tex]
For MES,
[tex]pK_{a}=-log K_{a}[/tex]
Put the value into the formula
[tex]pK_{a}=-log(7.9\times10^{-7})[/tex]
[tex]pK_{a}=7.0-log7.9[/tex]
[tex]pK_{a}=6.1[/tex]
pH range for best buffer,
[tex]pH=pK_{a}\pm 1[/tex]
Put the value into the formula
[tex]pH=6.1\pm 1[/tex]
[tex]pH=7.1, 5.1[/tex]
The pH value of the solution between 7.1 to 5.1.
This is not best buffer.
For HEPES,
[tex]pK_{a}=-log K_{a}[/tex]
Put the value into the formula
[tex]pK_{a}=-log(3.2\times10^{-3})[/tex]
[tex]pK_{a}=3.0-log3.2[/tex]
[tex]pK_{a}=2.5[/tex]
pH range for best buffer,
[tex]pH=pK_{a}\pm 1[/tex]
Put the value into the formula
[tex]pH=2.5\pm 1[/tex]
[tex]pH=3.5, 1.5[/tex]
The pH value of the solution between 3.5 to 1.5.
This is not best buffer.
For Tris,
[tex]pK_{a}=-log K_{a}[/tex]
Put the value into the formula
[tex]pK_{a}=-log(6.3\times10^{-9})[/tex]
[tex]pK_{a}=9.0-log6.3[/tex]
[tex]pK_{a}=8.2[/tex]
pH range for best buffer,
[tex]pH=pK_{a}\pm 1[/tex]
Put the value into the formula
[tex]pH=8.2\pm 1[/tex]
[tex]pH=9.2, 7.2[/tex]
The pH value of the solution between 9.2 to 7.2.
This is not best buffer.
For formic acid,
[tex]pK_{a}=-log K_{a}[/tex]
Put the value into the formula
[tex]pK_{a}=-log(1.8\times10^{-4})[/tex]
[tex]pK_{a}=4.0-log1.8[/tex]
[tex]pK_{a}=3.7[/tex]
pH range for best buffer,
[tex]pH=pK_{a}\pm 1[/tex]
Put the value into the formula
[tex]pH=3.7\pm 1[/tex]
[tex]pH=4.7, 2.7[/tex]
The pH value of the solution between 4.7 to 2.7.
This is best buffer.
For acetic acid,
[tex]pK_{a}=-log K_{a}[/tex]
Put the value into the formula
[tex]pK_{a}=-log(1.8\times10^{-5})[/tex]
[tex]pK_{a}=5.0-log1.8[/tex]
[tex]pK_{a}=4.7[/tex]
pH range for best buffer,
[tex]pH=pK_{a}\pm 1[/tex]
Put the value into the formula
[tex]pH=4.7\pm 1[/tex]
[tex]pH=5.7, 3.7[/tex]
The pH value of the solution between 5.7 to 3.7.
This is best buffer
Hence, Formic acid and Acetic acid is the best buffer at pH 3.7.
What is 0.75140000 in scientific notation?
Answer:
i need help too
Explanation:
helppp
In what two ways can an object possess energy?
Explanation:
An object can possess energy in tow ways by it's motion or position
What is the half-life of polonium-210 if it takes 828 days for a sample to be reduced to 1.6% of its original mass?
Answer:
The half-life of polonium-210 is approximately 138.792 days.
Explanation:
We must remember that the decay of a radioisotope is modelled by this ordinary differential equation:
[tex]\frac{dm}{dt} = -\frac{m(t)}{\tau}[/tex]
Where:
[tex]m(t)[/tex] - Current mass of the isotope, measured in grams.
[tex]\tau[/tex] - Time constant, measured in days.
Whose solution is:
[tex]m(t) = m_{o}\cdot e^{-\frac{t}{\tau} }[/tex]
Where [tex]m_{o}[/tex] is the initial mass of the isotope, measured in grams.
Our first step is to determine the value of the time constant:
[tex]-\frac{t}{\tau} = \ln \frac{m(t)}{m_{o}}[/tex]
[tex]\tau = -\frac{t}{\ln \frac{m(t)}{m_{o}} }[/tex]
If we know that [tex]\frac{m(t)}{m_{o}} = 0.016[/tex] and [tex]t = 828\,days[/tex], then the time constant of the radioisotope is:
[tex]\tau = -\frac{828\,days}{\ln 0.016}[/tex]
[tex]\tau \approx 200.234\,days[/tex]
And lastly we find the half-life of polonium-210 ([tex]t_{1/2}[/tex]), measured in days, by using this expression:
[tex]t_{1/2} = \tau \cdot \ln 2[/tex]
[tex]t_{1/2} = (200.234\,days)\cdot \ln 2[/tex]
[tex]t_{1/2}\approx 138.792\,days[/tex]
The half-life of polonium-210 is approximately 138.792 days.
At room temperature 20 Celsius and object had a mass of 25g and displaces 15 mL water in a cylinder. what is it’s density? If the object was cooled to point where it had only half of its original thermal energy. What would be it’s temperature in Kelvin and Celsius?
Answer:
Density = 1.67 g/cm³
New Temperature = 10°C ⇔ 283K
Explanation:
a. Density of a substance can be described as the mass (in grams) of a substance per litre (in mL or cm³) of liquid displaced.
Hence: Density = mass ÷ volume
Density = 25 ÷ 15
Density = 1.67 g/cm³
b. If the object is cooled to half of its original temperature, the new temperature is assumed to be half of the room temperature
Hence, the substance's new temperature will be = 20÷2
=10°C ⇔ 283K (i.e 10 + 273)
Suppose that 10.0 mol C2H6(g) is confined to 4.860 dm3 at 27 °C. Predict the pressure exerted by the ethane from (i) the perfect gas and (ii) the van der Waals equations of state. Calculate the compression factor based on these calculations. For ethane, a = 5.507 dm6 atm mol−2, b = 0.0651 dm3 mol−1.
Answer:
[tex]P=35.16[/tex]
[tex]Z=4.6[/tex]
Explanation:
Hello,
In this case, since the VdW equation is:
[tex]P=\frac{nRT}{V-n*b}-a(\frac{n}{V} )^2[/tex]
Since the moles are 10.0 moles, the temperature in K is 300.15 K and the volume is liters is also 4.860 L (1 dm³= 1L), the pressure exerted by the ethane is:
[tex]P=\frac{10.0mol*0.082\frac{atm*L}{mol*K}*300.15K}{4.860mol-10.0mol*0.0651\frac{L}{mol} }-5.507\frac{atm*L^2}{mol^2}(\frac{10.0mol}{4.86L} )^2\\\\P=58.48atm-23.3atm\\\\P=35.16[/tex]
Thus the compression factor turns out:
[tex]Z=\frac{PV}{RT}=\frac{23.3atm*4.86L}{ 0.082\frac{atm*L}{mol*K}*300.15K}\\\\Z=4.6[/tex]
Regards.
What are the effects of inhalation of acetone vapor?
Answer:
it can cause irritation in eyes throat and lungs and u can become lightheaded, or possibly fall in a coma
17. SiH3P
How do you create a Lewis structure for this formula?
Answer:
See attached picture.
Explanation:
Hello,
In this case, considering that Lewis structures are drawn in order to show up the bonding among equal or different atoms via their valence electrons, since hydrogen has one valence electron, silicon four and phosphorous five, the most suitable way to draw and attain the octet for both silicon and phosphorous is by bonding them via a double bond, one hydrogen bonded to the phosphorous and two hydrogen atoms bonded to the silicon as shown on the attached picture, wherein you can count eight electrons for both phosphorous and silicon.
Best regards.
Calculate the [OH-] and the pH for a solution of 0.24M methylamine, CH3NH2. Kb = 3.7 X 10-4.
Answer:
[tex][OH^-]=9.24x10^{-3}M[/tex].
[tex]pH=11.97[/tex].
Explanation:
Hello,
In this case, since the ionization of methylamine is:
[tex]CH_3NH_2(aq)+H_2O(l)\rightleftharpoons CH_3NH_3^+(aq)+OH^-(aq)[/tex]
The equilibrium expression is:
[tex]Kb=\frac{[CH_3NH_3^+][OH^-]}{[CH_3NH_2]}[/tex]
And in terms of the reaction extent [tex]x[/tex] which is equal to the concentration of OH⁻ as well as that of CH₃NH₃⁺ via ice procedure we can write:
[tex]3.7x10^{-4}=\frac{x*x}{024-x}[/tex]
Whose solution for [tex]x[/tex] via quadratic equation is 9.24x10⁻³ M since the other solution is negative so it is avoided. Therefore, the concentration of OH⁻ is:
[tex][OH^-]=x=9.24x10^{-3}M[/tex]
With which we can compute the pOH at first:
[tex]pOH=-log([OH^-])=-log(9.24x10^{-3})=2.034[/tex]
Then, since pH and pOH are related via:
[tex]pH+pOH=14[/tex]
The pH turns out:
[tex]pH=14-pOH=14-2.034\\\\pH=11.97[/tex]
Best regards.
Dogs can be acutely poisoned if they eat very small amounts of , a sweetener commonly found in sugar-free gum.
Answer:
Xylitol
Please give me the brainliest if you found this helpful
What is the period number in which helium is found
Answer:
Helium is the second element on the periodic table. It is located in period 1 and group 18 or 8A on the righthand side of the table. This group contains the noble gases, which are the most chemically inert elements on the periodic table. Each He atom has two protons and usually two neutrons and two electrons.
Explanation:
thoughtco.com
Answer:
period 1 and group 18 or 8A on the righthand side of the table.
Explanation:
A plate moves 200 m in 10,000 years. What is its rate in cm/year?
Answer:
The answer is
2 cm/yearExplanation:
To find the rate in cm/year we must first convert 200 m into cm
1 m = 100 cm
if 1 m = 100 cm
Then 200 m = 200 × 100 = 20 ,000 cm
So the rate is
[tex] \frac{20000}{10000} [/tex]Reduce the fraction with 10,000
We have the final answer as
2 cm/yearHope this helps you
Answer:
2 CM/year just now got 100 Edge.
Explanation:
Number of electrons absorbed by the main energy level (n = 4):
a)8
b)18
c)32
d)56
Answer:
C
Explanation:
Because 2 x n square gives the total energy level been absorbed = 2 x16
=32
What did Aristotle believe?
Calculate the molar solubility of CaF2 in a 0.25 m solution of NaF(aq).
(Ksp (CaF2) = 4.0 x 10-11)
Answer:
6.4 × 10^-10 M
Explanation:
The molar solubility of the ions in a compound can be calculated from the Ksp (solubility constant).
CaF2 will dissociate as follows:
CaF2 ⇌Ca2+ + 2F-
1 mole of Calcium ion (x)
2 moles of fluorine ion (2x)
NaF will also dissociate as follows:
NaF ⇌ Na+ + F-
Where Na+ = 0.25M
F- = 0.25M
The total concentration of fluoride ion in the solution is (2x + 0.25M), however, due to common ion effect i.e. 2x<0.25, 2x can be neglected. This means that concentration of fluoride ion will be 0.25M
Ksp = {Ca2+}{F-}^2
Ksp = {x}{0.25}^2
4.0 × 10^-11 = 0.25^2 × x
4.0 × 10^-11 = 0.0625x
x = 4.0 × 10^-11 ÷ 6.25 × 10^-2
x = 4/6.25 × 10^ (-11+2)
x = 0.64 × 10^-9
x = 6.4 × 10^-10
Therefore, the molar solubility of CaF2 in NaF solution is 6.4 × 10^-10M
The molar solubility should be 6.4 × 10^-10 M
Calculation of the molar solubility:Here
CaF2 will dissociate should be
CaF2 ⇌Ca2+ + 2F-
where,
1 mole of Calcium ion (x)
2 moles of fluorine ion (2x)
Now
NaF will also dissociate like
NaF ⇌ Na+ + F-
Here
Na+ = 0.25M
F- = 0.25M
Now
Ksp = {Ca2+}{F-}^2
Ksp = {x}{0.25}^2
4.0 × 10^-11 = 0.25^2 × x
4.0 × 10^-11 = 0.0625x
x = 4.0 × 10^-11 ÷ 6.25 × 10^-2
x = 4/6.25 × 10^ (-11+2)
x = 0.64 × 10^-9
x = 6.4 × 10^-10
Therefore, the molar solubility of CaF2 in NaF solution is 6.4 × 10^-10M
Learn more about solution here: https://brainly.com/question/14619461
a non-aqueous solution has a solvent that is not water. which is an example of a non aqueous solution?
paint
steel
orange juice
shaving cream
i’m confused because normally paint would be classified as a heterogenous mixture (not a solution) but the only other logical answer is orange juice but that is aqueous since it’s a solution based off the natural waters found in the orange. :/
Answer:
It is B. Steel
Explanation:
Answer:
Defenitly B !!
( Steel )
Explanation:
Which of the following elements is among the alkali metals?
Answer:
Alkali metals are: Lithium(Li), Sodium(Na), Potassium(K), Rubidium(Rb), Cesium(Cs) and Francium(Fr).
Explanation:
I cant understand your question mate, but these are all the alkali metals, because they are in the first group. Note that Hydrogen(H) is not an alkali metal. Hope that helps. God bless you.
The alkali metals are lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr).
What is the periodic table?The periodic table has been the arrangement of the elements based on the reactivity and the electrons in the valence shell.
The left side of the periodic table has been consisted of the metals, while moving from left to right the metallic character decreases and the nonmetallic character increase.
The group 1 of the periodic table has been consisted of the metals with 1 valence electrons. The group has been termed as alkali metals, as the reaction of the elements of this group with water forms alkali.
The elements belonging to group 1 of the periodic table are lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr).
Learn more about periodic table, here:
https://brainly.com/question/11155928
This is for my Science assignment: A molecule is made up of at least (blank) different atoms. Fill in the blank, please. Best answer gets Brainliest!
Answer:
2 differet atoms.
Explanation:
Molecule: group of two or more atoms held together by chemical bonds. So, minimum 2 atoms are required to form a molecule.
Which of the following describes the formation of an ionic bond
Explanation:
loosing or gaining one or more electrons
how are the troposphere and the thermosphere alike
What is the potential energy of the ball when it gets to its maximum height just before falling back to the ground?J
Answer:
9.8 joules
Explanation:
due to acceleration due to gravity
An air conditioning unit turns off once it reaches its goal temperature. The house warms up and the air conditioning unit turns on again.
When the air conditioning unit turns on, it is an example of:
A) input
B) process
C) output
D) feedback
Answer:
D) feedback.
Explanation:
An air condtioning unit consists of the following elements according to available choices:
Inputs: Refrigerant, air from surroundings, electricity.
Process: Refrigeration cycle.
Output: Conditioned air at goal temperature.
Feedback: Activation and deactivation of the air conditioning unit depending on indoor temperature.
When the air conditioning turns on and off to keep goal temperature indoors, a control stage consisting in a controller and a action element is acting to reverse the behavior of the process with a view to keep goal temperature.
Hence, correct answer is D.
Amoeba eat by using. What method
Answer:
Amoebas use their pseudopods to ingest food by a method called phagocytosis (Greek: phagein, to eat). The streaming of protoplasm inside the pseudopods moves the amoeba forward.
Explanation:
Write the net ionic equation for the reaction that takes places between aqueous copper and nitrate.
Answer:
Cu+HNO3
Explanation:
Several properties of the element magnesium are shown. Which one is a chemical property?
O A. has a density of 1.7 g/cm3
B. melts at 650°C
C. conducts electricity
D. has a silvery-white color
E. burns when exposed to heat
Answer:
E
Explanation:
burning a substance changes it chemically.
A gas cylinder is filled with silane (SiH4), used in semiconductor processes. The cylinder’s internal volume is 2.40 L, and it contains 542 g of the compound. Estimate the pressure inside the cylinder at 21oC. The properties of silane: Tc = 269.7 K, Pc = 48.4 bar, and ω = 0.094.
Answer:
The value is [tex]P = 7.8 *10^{6} \ Pa [/tex]
Explanation:
From the question we are told that
The internal volume is [tex]V_i = 2.40 \ L = 2.40 *10^{-3} \ m^3[/tex]
The mass of the compound contained is [tex]m = 542 \ g[/tex]
The temperature is [tex]T = 21^o C = 21 + 273 = 294 \ K[/tex]
The critical temperature of silane is [tex]T_c = 269.7 \ K[/tex]
The critical pressure of silane is [tex]P_c = 48.4 bar = 48.4 *10^{5} \ Pa[/tex]
Generally the number of moles of silane inside the cylinder is mathematically represented as
[tex]n = \frac{m}{M}[/tex]
here M is the molar mass of silane with value [tex]M = 32 g/mol[/tex]
So
[tex]n = \frac{542}{32}[/tex]
=> [tex]n = 16.4 \ mol[/tex]
Generally the molar volume of silane in the cylinder is mathematically represented as
[tex]Vn = \frac{V_i}{n}[/tex]
=> [tex]Vn = \frac{2.40 *10^{-3}}{16.4}[/tex]
=> [tex]Vn = 1.42*10^{-4} \ m^3 / mol[/tex]
Generally from Soave-Redlich-Kwon we have that
[tex]P = \frac{RT}{V_n - b} - \frac{a}{V_n (V_n + b)}[/tex]
Here b is a constant which is mathematically represented as
[tex]b = 0.08664 * \frac{R T_c }{P_c}[/tex]
substituting [tex]8.314 J/mol\cdot K[/tex] for R we have \
[tex]b = 0.08664 * \frac {8.314* 269.7}{48.4*10^{5}}[/tex]
[tex]b = 4.0139 *10^{-5} m^3/mol[/tex]
a is also a constant which is mathematically represented as
[tex]a = 0.42748 * \frac{(R * T_c)^2}{P_c} * (1 + m [1-\sqrt{T_r} ])^2[/tex]
Here [tex]T_r[/tex] is the reduced temperature which is mathematically represented as
[tex]T_r = \frac{T}{T_c}[/tex]
=> [tex]T_r = 1.09[/tex]
m is a constant which is mathematically represented as
[tex]m = 0.480 + 1.574w - 0.176w^2[/tex]
=> [tex]m = 0.480 + 1.574 (0.094) - 0.176(0.094)^2[/tex]
=> [tex]m = 0.626[/tex]
So
[tex]a = 0.42748 * \frac{(8.314 * 269.7)^2}{48.4*10^{5}} * (1 + 0.626 [1-\sqrt{1.09} ])^2[/tex]
[tex]a = 0.4198[/tex]
From [tex]P = \frac{RT}{V_n - b} - \frac{a}{V_n (V_n + b)}[/tex] we have
[tex]P = \frac{8.314 * 294}{1.42*10^{-4} - 4.0139 *10^{-5} } - \frac{0.626}{1.42*10^{-4} (1.42*10^{-4} + 4.0139 *10^{-5} )}[/tex]
[tex]P = 7.8 *10^{6} \ Pa [/tex]
What is the difference between dehydration and hydrolysis?
Answer:
Some differences between the given particular topics are described below.
Explanation:
Hydrolysis occurs as the water is absorbed in some kind of a response to breaking up the polymer through its corresponding monomers while Dehydration synthesis happens whenever water has been formed as a formation of the polymerization of the latter's corresponding monomers.Hydrolysis seems to be a method during which a chemical bond becomes dissolved by a water molecule while Dehydration would be a state of consuming less liquid than that of the natural rate.Two separate pure samples of carbon dioxide were analyzed. Both samples were found to contain 27.29% carbon by mass. Justify these findings on the basis of atomic molecular theory.
Answer:
Atoms of the same element are exactly alike in all respects and are different from atoms of other elements.
Explanation:
One of the postulates of the Dalton's atomic theory is that 'Atoms of the same element are exactly alike in all respects and are different from atoms of other elements.'
Hence, if carbon dioxide from two sources are obtained and analysed, the mass percentage of carbon in both samples should be exactly the same since they both contain atoms of carbon. The atoms of carbon in the both samples are exactly the same in all respects in accordance with the Dalton's atomic theory, hence the observation.
what have you learned about the four subsystem?
Calculate the [H+] and pH of a 0.000185 M acetic acid solution. Keep in mind that the Ka of acetic acid is 1.76×10−5. This is a problem that will require you to use the quadratic. Start by setting up the quadratic equation before using the quadratic formula and find the coefficients. Then, solve the quadratic. Quadratic formula: ax2+bx+c=0; enter the values of a, b, and c
Answer:
[H⁺] = 0.000048936M
pH = 4.31
Explanation:
Acetic acid, CH₃COOH, dissociates in water as follows:
CH₃COOH(aq) ⇄ H⁺(aq) + CH₃COO⁻(aq)
And Ka is defined as:
Ka = 1.76x10⁻⁵ = [H⁺] [CH₃COO⁻] / [CH₃COOH]
Where [] are equilibrium concentrations of the species.
The 0.000185M of acetic acid will decreases X, and X of [H⁺] and [CH₃COO⁻] will be produced. That means Ka is:
1.76x10⁻⁵ = [X] [X] / [0.000185 - X]
3.256x10⁻⁹ - 1.76x10⁻⁵X = X²
3.256x10⁻⁹ - 1.76x10⁻⁵X - X² = 0
Solving for X:
X = -0.000066M → False solution. There is no negative concentrations.
X = 0.000048936
As [H⁺] = X,
[H⁺] = 0.000048936M
And pH = -log [H⁺]
pH = 4.31The reason a theory may be changed or thrown out is
Answer:
If it is not proven and if it isn't backed up by any facts or has been proven to be false.
