Answer:
D H2PO4– + HPO42–
Explanation:
The acid dissociation constant for [tex]\mathbf{H_3PO_4 , H_2PO^{-}_4 , HPO_4^{2-}}[/tex] are [tex]\mathbf{7\times 10^{-3}, \ \ 8\times 10^{-8} ,\ \ 5\times 10^{-13}}[/tex] respectively.
[tex]\mathbf{pka (H_3PO_4) = -log (7\times 10^{-3} )=2.2}[/tex]
[tex]\mathbf{pka (H_2PO_4^-) = -log (8\times 10^{-8} )=7.1}[/tex]
[tex]\mathbf{pka (HPO_4^{2-}) = -log (5\times 10^{-13} )=12.3}[/tex]
The reason while option D is the best answer is that, the value of pKa for both
[tex]\mathbf{H_2PO^{-}_4 ,\ \& \ HPO_4^{2-}}[/tex] lies on either side of the desired pH of the buffer. This implies that one is slightly over and the other is slightly under.
Using Henderson-Hasselbach equation:
[tex]\mathbf{pH = pKa + log \Big( \dfrac{HPO_4^{2-}}{H_2PO_4^-} \Big)}[/tex]
The compounds that are used for the formulation of the pH 9 buffer are [tex]\rm H_2PO_4^-\;and\;HPO_4^+[/tex]. Thus, option D is correct.
The buffers are the solutions of acids and base of appropriate pH, that are able to limit the change in pH in the reaction mixture.
Which compound is used for pH 9 buffer?The buffer pH is adjusted with the compounds that has been able to add base or acid to the solution.
For the formulation of buffer of specific pH, the acid and base solutions are required.
The compounds that are used for the formulation of the pH 9 buffer are [tex]\rm H_2PO_4^-\;and\;HPO_4^+[/tex], as they are able to provide acid and base to the solution.
Thus, option D is correct.
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3. Una piedra que se tira verticalmente hacia arriba se mueve según la
leys = 64y - 8t^2, si "s" se mide en pies (ft) y t en segundos, hallar:
a) SU posición y velocidad después de dos segundos y después de tres
segundos.
b) ¿Qué altura alcanzará?
c) ¿A qué distancia se moverá al cabo del cuarto segundo?
Answer:
Explanation:
Para mejor entendimiento, reeescribiremos la ley que pusiste:
S = 64t - 8t² (1)
De acuerdo al enunciado del problema, S tiene unidades de pie y t en segundos, por lo tanto, S, que se refiere a la posición o altura alcanza de la piedra, puede ser determinado usando esa expresión a tiempos específicos.
Para el calculo de velocidad usamos la siguiente expresión:
V = -g * t (2) g: 32.16 ft/s
Tomando en cuenta estas expresiones, veamos los valores de posición y velocidad:
a) Para t = 2 s
S = 64(2) - 8(2)²
S = 96 ft
V = -32.16 * 2
V = -64.32 ft/s
Para t = 3 s
S = 64(3) - 8(3)²
S = 120 ft
V = -32.16 * 3
V = -96.48 ft/s
b) Para saber la altura que alcanzará, usamos la expresión de altura máxima que es la siguiente:
Smáx = -V₀² / 2g (3)
Para el valor de la velocidad inicial, podemos asumir el valor de la velocidad dada por la formula de la ley S, que es 64. Esto porque al ser multiplicado por el valor del tiempo, queda en unidades de distancia, asi que este valor debe tener unidades de velocidad. Reemplazando este valor en la expresión:
Smáx = -(64)² / 2 * 32.16
Smáx = 63.68 ft
c) Para esta parte, usamos nuevamente la formula de la ley S, usando t = 4 s y listo:
S = 64(4) - 8(16)
S = 128 ft
Espero te sirva
Prokaryotic cell division is a___________process involving onc chromosom.
A. simple
B. complex
C. unusual
Answer:
It’s is a simple
Explanation:the prokaryotic cell involves a simple process which intern involves one chromosom
Excess silver(I) nitrate was added to a 8.500 g mixture containing some amount of barium chloride, and 7.123 g of silver chloride was obtained. The unbalanced equation is
AgNO3 + BaCl2(aq) --> Ba(NO3)2(aq) + AgCl(s).
What is the mass% of BaCl2 in the mixture?
Answer:
60.88%
Explanation:
The balanced equation of the reaction is given as;
2 AgNO3 (aq) + BaCl2 (aq) → 2 AgCl (s) + Ba(NO3)2 (aq)
Since AgNO3 is in excess, the limiting reactant is BaCl2. From the reaction;
1 mol of BaCl2 produces 2 mol of AgCl
Converting to masses;
Mass = Number of mol * Molar mass
BaCl2;
Mass = 1 * 208.23 g/mol = 208.23 g
AgCl;
Mass = 2 * 143.32 g/mol = 286.64 g
208.23 g BaCl2 produces 286.64 g of AgCl
x g BaCl2 produces 7.123 g of AgCl
Solving for x;
x = 7.123 * 208.23 / 286.64 = 5.1745 g
Mass percent = Mass / Total mass of Mixture * 100
Mass Percent = 5.1745 / 8.500 = 0.6088 * 100 = 60.88%
Iron-59 which is used to diagnose anaemia has a half life of 45days, what fraction of it is left in 90 days
Answer:
0.25 of the original
Explanation:
(0.5)^(90/45)
The fraction of iron-59 after 90 days is 0.25.
Iron-59 decays following first-order kinetics. Given the half-life ([tex]t_{1/2}[/tex]) of 45 days, we can calculate the rate constant (k) using the following expression.
[tex]k = \frac{ln2}{t_{1/2}} =\frac{ln2}{45day} = 0.015 d^{-1}[/tex]
For first-order kinetics, we can find the fraction of Fe ([Fe]/[Fe]₀) after and an elapsed time (t) of 90 days, using the following equation.
[tex]\frac{[Fe]}{[Fe]_0} =e^{-k \times t } = e^{-0.015 d^{-1} \times 90 d } \approx 0,25[/tex]
The fraction of iron-59 after 90 days is 0.25.
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which one of the following are pure substances : water,salt water,copper,brass,air,oxygen
Answer:
Copper, Water, and Oxygen
Explanation:
Because they are compounds and compounds are pure substances <3
Answer: copper
Explanation: because all of the atoms that make up copper are copper i.e its not a compound or mixture. not made od molecules
The map shows the average high temperatures in July for two cities in Texas.
Average July High Temperatures
Texas
Del Rio
36°C
Galveston
32°C 12
Answer:
Highest temperature which was recorded in Texas was 40 degrees.
Explanation:
Texas has variating weather. In summer Texas city turns to be very hot and during winters the city of Texas experience fall in temperature. There is very few rainfall in Texas due the climatic conditions.
Determine whether each observation generally corresponds to a physical change or a chemical change. A liquid freezes into a solid. _________ Bubbles are produced upon mixing two solutions. __________ A precipitate is formed from two solutions. _________ A solution heats up upon mixing with another. ____________ A solid dissolves into water. __________ The color of a substance changes over time
Answer:
A liquid freezes into a solid or any other state change is a physical change. Bubbles are produced upon mixing two solutions is a Chemical change as gas formed. a precipitate is formed from two solutions is a Chemical change The conversion of a substance to another compound over time leads to a color change of the substance due to the insolubility of the compound.
It is a chemical change or properties. A solution that heats up upon mixing with another is a Chemical change known as an exothermic reaction. dissolving the substance in a liquid is a physical change physical that can be regained by evaporation or crystalization.
Is snow organic or inorganic?
Answer:
snow is made up of a variety of mostly organic matter, including dead or dying animals and phytoplankton, protists, fecal matter, sand, and other inorganic dust.
Explanation:
I hope I helped!!
Plz mark me brainliest it would really make my day!
Answer:
I think its organic unless we are talking about this snow storm then no
What is the main FUNCTION of the digestive system?
What are some of the main organs of the digestive system?
3. Which state of matter has a defined shape?
HELP FAST
Answer:
Solid state of matter has a definite shapeThe answer to this is solids!
the Rockies and the Appalachians are two major mountain ranges in the United States. Which type of plate movement caused these mountain ranges to form
Answer:
Convergent
Explanation:
I don't know whether this is one of your answers but It is convergent because convergent boundaries are when two plates collide against each other which can create mountains and volcanos.
If the mercury in a manometer raises 30.0 millimeters due to a change in pressure, what is the corresponding change in pressure in atm?
Answer:
0.03947 atm
Explanation:
The relationship between mmHg and atm is given as;
1 atm = 760 mmHg
x atm = 30 mmHg
Upon solving for x;
x * 760 = 30 * 1
x = 30 / 760 = 0.03947 atm
At room temperature, CsF is expected to be:______.
a. a soft solid.
b. a conducting solid.
c. a gas.
d. a brittle solid.
e. a liquid.
Answer:
d. a brittle solid.
Explanation:
Hello!
In this case, since cesium fluoride is widely known as an ionic compound due to the large electronegativity difference, it is possible to discard a. due to its crystalline structure, b. because conducting solids are metals, c. because ionic compounds are not likely to be gases and e. because even when it is soluble in water, the problem is not referring to an aqueous solution; therefore, the answer is d. a brittle solid.
Best regards!
Both amines and amides are derivatives of
acetic acid
sodium hydroxide
ammonia
sodium chloride
Answer:
Ammonia
Explanation:
Both amines and amides are structurally similar to ammonia, the difference is the introduction of a carbon into the structure.
. Which state of matter has a defined volume but no defined shape?
HELPPPP PLEASE FAST
Answer:
liquid
Explanation:
it's not plasma, solid, or gas
so I think liquid
What are the main sources of outdoor air pollution and how do they cause smog?
Answer:
The common sources of outdoor air pollution are emissions caused by combustion processes from motor vehicles, solid fuel burning and industry. Other pollution sources include smoke from bushfires, windblown dust, and biogenic emissions from vegetation (pollen and mold spores).
smog is produced when sunlight reacts with nitrogen oxides in the atmosphere. Nitrogen oxides come from car exhaust, coal power plants, and factory emissions. When sunlight hits these chemicals, they form airborne particles and ground-level ozone—or smog.
Help! I’ll give brainliest if u get it right!
Answer:
That is the Atomic mass
Explanation:
The element symbol is S, Element name is sulfur, and
Atomic number is 16
Titanium(IV) chloride decomposes to form titanium and chlorine, like this:
TiCl4(l) → Ti(s)+ 2Cl2(g)
At a certain temperature, a chemist finds that a reaction vessel containing a mixture of titanium(IV) chloride, titanium, and chlorine at equilibrium has the following composition:
Compound Amount
TiCl4 4.18g
Ti 1.32g
Cl2 1.08g
Required:
Calculate the value of the equilibrium constant for this reaction.
The full question is shown in the image attached to this answer
Answer:
6.2 * 10^-3
Explanation:
The reaction at equilibrium is as follows;
TiCl4(l) → Ti(s)+ 2Cl2(g)
We have to obtain the concentration of chlorine gas as follows;
[Cl2] = 1.08/70.91 g/mol × 5.2 L
[Cl2] = 0.079 M
Kc = [Cl2]^2
Kc = [ 0.079]^2
Kc = 6.2 * 10^-3
Fred is about to order a stack of four pancakes with butter and syrup, but he wonders how much he would need to exercise to burn off the Calories from it. He pulls out his cell phone and finds the nutritional information for the stack of pancakes. He notes that a serving has 181g of carbohydrates, 27g of fat, and 16g of protein. Now, he has to convert these values into Calories.
Running at a pace of 8 minutes per mile burns 14 Calories/minute. How many minutes would he have to run at an 8 minutes per mile pace to bum off the Calories from the stack of pancakes?
Answer:
The correct answer is - 73.64 minutes.
Explanation:
We know that each gram of protein and carbohydrate produces 4 calories of energy whereas fat produces 9 cal energy per gram.
So, the Calories from carbohydrates
= 181 ×4
= 724 Cal
and, 27 g fat produces = 27 × 9 = 243 Cal
and, 16 g protien = 16 × 4 = 64 Cal
so the total energy will be - 243+ 724+ 64 = 1031 Cal
Thus, the time Fred need to run = 1031/14 =73.64 min
Father, I come to you worn and weary from the hard times I have walked through recently. I come to you seeking your shelter where I know I can find security and rest in your shadow. Father, you are mighty. I know my circumstances are no match for Your great power. Father I place a healing of these people that they feel a conviction in there heart that they would turn from there wicked way and turn to you father. IN JESUS NAME AMEN
Answer:
Fact: There’s only one letter that doesn’t appear in any U.S. state name
And that is Q
Explanation:
What is the surface composition of planets in the solar system?
A,. Helium or hydrogen
B,. Rock or gas
C., Rock or water
D,. Water or helium
Answer:
A: Helium or Hydrogen
Explanation:
Terrestrial planets are the 4 inner most planets of the solar system which are mercury, venus, earth, Mars, while the giant planets are the 4 outer most which are Jupiter, Saturn, Uranus and Neptune.
Now, these outer most ones are the surface ones and are surrounded primarily by layers of hydrogen and helium gases.
How many moles are there in 2.30 x 1024 atoms of silver?
Answer:
Step 1 should be convert atoms to moles (n). Step 2 should be convert moles (n) to mass (m).
Step 1
Use dimensional analysis to convert the number of atoms to moles.
1 mole atoms = 6.022 × 10²³ atoms
n(Ag) = 2.3 × 10²⁴ Ag atoms × (1 mol Ag/6.022 × 10²³ Ag atoms) = 3.8193 mol Ag
Step 2
Convert the moles of Ag to mass.
mass (m) = moles (n) × molar mass (M)
n(Ag) = 3.8193 mol Ag
M(Ag) = atomic weight on the periodic table in g/mol = 107.868 g Ag/mol Ag
m(Ag) = 3.8193 mol × 107.868 g/mol = 412 g Ag = 410 g Ag rounded to two significant figures
The mass of 2.3 × 10²⁴ Ag atoms is approximately 410 g.
Explanation:
The number of moles that are present is 2.3 × 10²⁴ atoms of silver are 3.8193 moles that can be determined using Avogadro's law.
The calculation for number of moles:One mole:
A mole is defined as 6.022 × 10²³ of some chemical unit, be it atoms, molecules, ions, or others.
1 mole = 6.022 × 10²³ atoms
n(Ag) = 2.3 × 10²⁴ Ag atoms × (1 mol Ag/6.022 × 10²³ Ag atoms)
n(Ag) = 3.8193 mol Ag
Thus, the number of moles is 3.8193 moles.
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How many CaF are in a 1.7x10^25 please I need help fast!!
28 mol CaF
General Formulas and Concepts:Math
Pre-Algebra
Order of Operations: BPEMDAS
Brackets Parenthesis Exponents Multiplication Division Addition Subtraction Left to RightChemistry
Atomic Structure
Avogadro's Number - 6.022 × 10²³ atoms, molecules, formula units, etc.Stoichiometry
Using Dimensional AnalysisExplanation:Step 1: Define
[Given] 1.7 × 10²⁵ molecules CaF
[Solve] moles CaF
Step 2: Identify Conversions
Avogadro's Number
Step 3: Convert
[DA] Set up: [tex]\displaystyle 1.7 \cdot 10^{25} \ molecules \ CaF(\frac{1 \ mol \ CaF}{6.022 \cdot 10^{23} \ molecules \ CaF})[/tex][DA] Multiply/Divide [Cancel out units]: [tex]\displaystyle 28.2298 \ moles \ CaF[/tex]Step 4: Check
Follow sig fig rules and round. We are given 2 sig figs.
28.2298 mol CaF ≈ 28 mol CaF
Put the following elements in order of increasing atomic number:
1. Strontium
2. Fluorine
3. Terbium
4. Zirconium
5. Iodine
6. Europium
7. Gallium
8. Aluminum
Answer:
Here is the answer ⬆️⬆️⬆️⬆️⬆️⬆️⬆️
The order of the given elements in increasing atomic number is given as F (9), Al (13), Ga (31), Sr (38), Zr (40), I(53) and Terbium (65).
What is atomic number?The atomic number of an element in periodic table is the number of electrons in its neutral atom. Elements are arranged in periodic table in an increasing order of atomic number from left to right.
An atom is composed of electrons, protons and neutrons. Protons are positively charged and electrons are negatively charged particles and they are equal in an atom. Thus, the total negative charge is neutralised by the negative charges.
The order for the given elements in periodic table in an increasing atomic number is F (9), Al (13), Ga (31), Sr (38), Zr (40), I(53) and Terbium (65).
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does a mole of hydrogen have the same mass as a mole of oxygen? explain your answer
What type of reaction
the following chemical reaction?
2C2H4O2 → C4H6O3 + H2O
DNA forms two strands. One of the strands of a piece of a DNA molecule has the bases ATA.
Which bases does the other strand have?
Select one:
A: CAC.
B: TAT.
C: GTG.
D: ATA.
Answer:
b
Explanation:
Combinations between two strands:
T - A
A - T
C - G
G - C
(so if one strand has A for example, then the other strand must have T in the same spot)
Bases which are present on the other strand of DNA are TAT.
What is DNA?DNA or deoxyribonucleic acid is a hereditary material present in humans as well as all living beings. Almost every cell present in the body has DNA. Most DNA are located inside the cell , that is in the nucleus of the cell. But a small portion of DNA can be found in the mitochondria of the cell as well.
The information in DNA is stored as a code which is composed of four chemical bases 1) adenine 2)guanine 3) cytosine 4) thymine . The human DNA consists of 3 billion bases . The order of of these bases determine information which is used for building and maintaining an organism.
The DNA bases can pair with each other .Adenine pairs with thymine and guanine with cytosine to form units which are called as base pairs.Each base apart from other complementary base it also attaches itself to a sugar and a phosphate molecule.
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Indicate whether each structure is aromatic, nonaromatic, or antiaromatic. Assume planarity. Compound A is a 5 membered heterocyclic ring containing two pi bonds. On one of the pi bonds is a sulfur with one lone pair and a positive charge. There is an N H group between the two pi bonds with one lone pair. Compound B is a 6 membered ring with three pi bonds. One of the ring atoms is a protonated oxygen with one lone pair. Compound C is an 8 membered ring with a double bond between carbons 2 and 3, between carbons 5 and 6 and between carbons 7 and 8. There is a positive charge on carbon 4 and a negative charge and lone pair on carbon 1. Compound D is a 7 membered ring with three pi bonds. In between two alkenes is a boron attached to a hydrogen. Comppound E is a 7 membered ring with three pi bonds. In between two alkenes is a negative charge with a lone pair.
Answer:
this some next level stuff homie
Explanation:
imma just guess 7?
The thing being described is shaped like a ring with five parts. Inside the ring, there are two special types of bonds. This has a sulfur that is positively charged and has one unshared pair, also it has an NH group with one unshared pair.
What is the structureCompound B is a substance that is made up of two or more different elements or molecules.
The thing being described has a ring with six members and three pi bonds. It has an oxygen atom with an extra proton and one extra electron. This substance is not aromatic.
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I need help answering number 14 A B and C. Thank you!
Answer:
Explanation:
TiO2 + C + 2 CI2 → TiCI4 + CO2
(a)
(2.16 mol TiO2) x (2 mol CI2 / 1 mol TiO2) x ( 70.9064 g C/mol) = 306 g CI2
(b)
(2.16 mol TIO2) x (1 mol C / 1 mol TiO2) x ( 12.01078 g C/mol)n= 25.9 g C
(c)
Use the law of conservation of mass:
(2.16 mol TiO2) x ( 79.8660 g TiO2/mol) + (306 g CI2 + 25.9 g C = 504 g total.
Hope this help!:)
You dissolve 0.64 g of potassium chloride (KCl) in 725 ml of water.
What is the molarity of the solution?
(From the periodic table: 1 mol K = 39.10 g; 1 mol Cl = 35.453 g)
Enter the value rounded to three decimal places with no units
Will give BRAINLEST
Answer:
0.012 M
Explanation:
Step 1: Given and required data
Mass of KCl (m): 0.64 gVolume of water (V): 725 mL (We will assume it is equal to the volume of the solution)Molar mass of KCl (M): 74.553 g/molStep 2: Calculate the moles (n) of solute (KCl)
We will use the following expression.
n = m/M = 0.64 g / (74.553 g/mol) = 8.6 × 10⁻³ mol
Step 3: Calculate the molar concentration (C) of the solution
The molarity is equal to the moles of solute divided by the liters of solution.
C = 8.6 × 10⁻³ mol/0.725 L = 0.012 M