calculate the ph of a buffer solution that is 0.250 m in hcn and 0.170 m in kcn . for hcn , ka=4.9×10−10 (pka=9.31) . use both the equilibrium approach and the henderson-hasselbalch approach.
Answers
The pH of the buffer solution is approximately 4.51
To calculate the pH of this buffer solution, we can use both the equilibrium approach and the Henderson-Hasselbalch approach.
Equilibrium Approach:
The equation for the dissociation of HCN is:
HCN + H2O ⇌ H3O+ + CN-
The Ka expression for this dissociation is:
Ka = [H3O+][CN-] / [HCN]
At equilibrium, the concentrations of HCN and CN- are:
[HCN] = 0.250 M
[CN-] = 0.170 M
Substituting these values into the Ka expression and solving for [H3O+] gives:
Ka = 4.9×10−10 = [H3O+]^2 / 0.250
[H3O+] = 7.0×10^-6 M
The pH of the buffer solution can be calculated as:
pH = -log[H3O+]
pH = -log(7.0×10^-6)
pH = 5.15
Henderson-Hasselbalch Approach:
The Henderson-Hasselbalch equation is:
pH = pKa + log([A-] / [HA])
In this case, the acid is HCN and its conjugate base is CN-.
The pKa of HCN is given as 9.31, which means:
pKa = -log(Ka)
9.31 = -log(4.9×10−10)
The concentrations of HCN and CN- are:
[HA] = [HCN] = 0.250 M
[A-] = [CN-] = 0.170 M
Substituting these values into the Henderson-Hasselbalch equation gives:
pH = 9.31 + log(0.170 / 0.250)
pH = 5.15
Both approaches give the same pH value of 5.15.
To calculate the pH of the buffer solution using both the equilibrium approach and the Henderson-Hasselbalch approach, we will use the given values of HCN and KCN concentrations and the Ka value of HCN.
Equilibrium Approach:
1. Write the equilibrium expression: Ka = [H+][CN-]/[HCN]
2. Ka = 4.9 × 10^(-10), [HCN] = 0.250 M, [CN-] = 0.170 M (KCN dissociates completely)
3. Solve for [H+]: [H+] = Ka × [HCN] / [CN-] = (4.9 × 10^(-10)) × (0.250) / (0.170)
4. [H+] ≈ 7.21 × 10^(-11) M
5. Calculate pH: pH = -log([H+]) ≈ 10.14
Henderson-Hasselbalch Approach:
1. Calculate pOH using pKa: pOH = pKa - log([CN-]/[HCN]) = 9.31 - log(0.170/0.250)
2. pOH ≈ 9.31 - (-0.176) = 9.49
3. Calculate pH: pH = 14 - pOH = 14 - 9.49 ≈ 4.51
There is a discrepancy between the two approaches due to approximations made in the equilibrium approach, which assumes that the change in [HCN] and [CN-] is negligible. The Henderson-Hasselbalch approach provides a more accurate result. In this case, the pH of the buffer solution is approximately 4.51.
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Related Questions
The __________ is the part of the solution that is in the greater quantity, and the __________ is the smaller portion of the solution.
solvent/solute
solute/solvent
mixture/compound
compound/mixture
Answers
Answer:
solvent/solute
Explanation:
because the solvent is what dissolves or what the solute is placed in e.g solvent =water and the solute is e.g =salt
6. ( i’ll award the brainliest and any “links” will be reported)
sodium metal reacts with water and produces aqueous sodium hydroxide and hydrogen gas
a. Translate the word equation, and write the complete and balanced chemical equation.
b. What volume of hydrogen gas can be produced from reacting 5.67 grams of sodium metal with excess
water?
C. What is the percent yield if 964.00 mL of H, are collected through experimentation?
Answers
Answer: 2Na+2H2O------>2NaOH+H2
b) From the equation two moles of sodium gave one mole of hydrogen.
At stp the volume of hydrogen is 22400cm3.
The molar mass of sodium is 23
So we have
2molesNa--->1moleH2
5.76moles--->? mole H2
Meaning
2(23)Na----> 22400cm3 ofH2
5.67Na---->?H2
22400×5.67÷ 2(23)
127008÷46=2761.04cm3
Sorry I can't do the last one.
Which of the following have the thickest layer of peptidoglycan in the cell wall?
mycoplasma
gram-positive bacteria
gram-negative bacteria
L-forms
Answers
The following have thickest layer of peptidoglycan in the cell wall : gram-positive bacteria
What is the thick layer of peptidoglycan?Thickened peptidoglycan layer in Gram positive cells allows them to retain the stain ( and hence remaining 'stain positive' or 'Gram positive) where as thin layer seen in Gram negative cells cannot prevent the stain from leeching out (and hence stain and Gram negative).
Gram-positive organisms have thicker peptidoglycan cell wall as compared to gram-negative bacteria. It is 20 to 80 nm thick polymer whereas peptidoglycan layer of the gram-negative cell wall is 2 to 3 nm thick and covered with outer lipid bilayer membrane.
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At a football stadium, 5% of the fans in attendance were teenagers. If there were 160 teenagers at the football stadium, what was the total number of people at the stadium?
Answers
Answer:
yes
Explanation:
bc god exist
Answer:
3200
Explanation:
Describe the formation of ions by electron loss or gain
Answers
Explanation:
Ions form when atoms gain or lose electrons. This is so that they form a full outer shell of electrons. When an atom gains electrons it becomes a negative ion, because electrons are negatively charged. For example, all halogens (group 7 or 17) form negative ions as they gain an electron forming a 1- charge. When an atom loses electrons it becomes a positive ion, as it is losing some negative charge from the electrons. This would be for example, alkali metals (group 1) which lose an electron to form a positive ion with a 1+ charge, (ALL metals form positive ions).
4. The equation for the decomposition of hydrogen peroxide is shown. 2H₂O₂(aq) → 2H₂O(l) + O₂(g) 48.0 25.0 cm³ of aqueous hydrogen peroxide forms 48.0 cm³ of oxygen at room temperature and pressure (r.t.p.). Calculate the concentration i aqueous hydrogen peroxide at the start of the experiment using the following steps ● Calculate the number of moles of oxygen formed. • Deduce the number of moles of hydrogen peroxide that decomposed. • Calculate the concentration of hydrogen peroxide in mol/dm³.
Answers
Answer:
Just add what they equal to hope this helps :)
Explanation:
What is the limiting reactant if 10 moles of NH3 react with 30.0 moles of NO? 4NH3+6NO → 5N2 + 6H2O
Answers
Explanation:
M
r
N
H
3
=
17
;
M
r
O
2
=
32
;
M
r
N
O
=
26
;
M
r
H
2
O
=
18
Using the equation:
Number of Moles = Mass / Mr
Number of Moles
N
H
3
=
175
17
=
10.3
Number of Moles
O
2
=
310
32
=
9.69
O
2
is the limiting reagent because the least moles of this are used in the reaction.
From the balanced equation, we can see that
O
2
and
N
O
are in a 5:4 ratio
5
4
=
0.8
9.69
×
0.8
=
7.75
7.75 moles of
N
O
is the maximum that can be produced from 310g of
O
2
. To convert this to mass we use the same equation as in the first step.
Mass = Moles x Mr
7.75
×
26
=
202
g
202g is the theoretical yield of
N
O
To calculate the percentage yield, you just divide the actual yield by the theoretical yield and multiply by 100:
197
202
×
100
=
98
%
The limiting reactant for the reaction between 10 moles of NH₃ and 30 moles of NO is NH₃.
The balanced equation for the reaction is given below:
4NH₃ + 6NO → 5N₂ + 6H₂O
From the balanced equation above,
4 moles of NH₃ reacted with 6 moles of NO.
With the above information, we can obtain the limiting reactant as follow:
From the balanced equation above,
4 moles of NH₃ reacted with 6 moles of NO.
Therefore,
10 moles of NH₃ will react with = \(\frac{10 * 6}{4}\\\\\) = 15 moles of NO.
From the calculation made above, we can see clearly that only 15 moles of NO out of 30 moles reacted completely with 10 moles of NH₃.
Therefore, NH₃ is the limiting reactant and NO is the excess reactant.
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write in the coefficients to balance the following reaction: febr3 h2so4→fe2(so4)3 hbr
Answers
The coefficients to balance the following reaction: febr3 h2so4 = fe2(so4)3 hbr are FeBr3, H2SO4, Fe2(SO4)3 and HBr.
The balanced chemical reaction is given as: FeBr3 + H2SO4 → Fe2(SO4)3 + 6HBr
The coefficients are given below:
FeBr3 (1) + H2SO4 (1) = Fe2(SO4)3 (1) + 6HBr (1)
The above-given equation is balanced by including the coefficients such that the number of atoms of the elements remains the same on both sides of the reaction.
To balance the given reaction, we need to add the coefficients to the reactants and products.
Therefore, the coefficients of FeBr3, H2SO4, Fe2(SO4)3 and HBr are 1, 1, 1, and 6, respectively.
The balanced chemical reaction is shown below:
FeBr3 (s) + H2SO4 (aq) → Fe2(SO4)3 (aq) + 6HBr (aq)
The balanced reaction states that 1 mole of FeBr3 reacts with 1 mole of H2SO4 to produce 1 mole of Fe2(SO4)3 and 6 moles of HBr.
Hence, the balanced chemical reaction can be achieved by adding the coefficients in the above-given equation. The number of atoms on both sides of the equation should be the same.
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the process of breathing involves exchanging oxygen for which other gas?
Answers
The process of breathing involves exchanging oxygen for carbon dioxide gas.
The process of breathing involves inhalation and exhalation.
Inhalation is the process of taking in oxygen and Exhalation is the process of taking out carbon dioxide. Air contains 21 % oxygen and 71 % nitrogen and 8 % other gases.
When we breathe in(inhalation) our diaphragm contracts downward while during breath out(exhalation) our diaphragm contracts upward. As food and water are important for us in similar way breathing is also essential for life.
So during the process of breathing, we take in oxygen and take out carbon dioxide.
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Which sequence of coal rank is ordered from lowest to highest, based on the amount of organic carbon contained within:
Answers
The sequence of coal from lowest to highest based on organic carbon contained within is peat, lignite, sub-bituminous, bituminous, anthracite.
What is Coal?This is a fossil fuel which is usually black in color and a combustible sedimentary rock.
There are different types of coal with the amount of organic carbon contained within from lowest to highest being shown above.
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Please answer both
The heat of vaporization for water is 2260 J/g. How much heat in J would be needed to evaporate 8.66g of water?
An unknown salt was dissolved to make a total 1.25g of solution. The temperature of the water decreased from 25.1C to 20.4C when 8mol were dissolved. What is the heat of solution in J/mol?
Answers
(a) We would need 19595.6 J of heat to evaporate 8.66 g of water.
(b) The heat of solution is -3.1 J/mol.
What is the heat needed to evaporate the water?To evaporate 8.66 g of water, we need to use the heat of vaporization for water, which is 2260 J/g.
Therefore, the total amount of heat required to evaporate 8.66 g of water is:
2260 J/g x 8.66 g = 19595.6 J
Therefore,
To find the heat of solution in J/mol, we need to use the formula:
ΔH_solution = -q_solution / n
where;
ΔH_solution is the heat of solution, q_solution is the heat released or absorbed during the solution process, n is the number of moles of solute dissolved.First, we need to calculate the heat released or absorbed during the solution process, which can be found using the formula:
q_solution = m_solution x C_solution x ΔT
We know that 8 mol of the unknown salt were dissolved in 1.25 g of solution, so the mass of the solute is:
m_solute = n x M
We also know that the temperature of the solution decreased from 25.1 ⁰C to 20.4 ⁰C, so ΔT = 4.7 K.
The specific heat capacity of water is 4.184 J/g·K, so we can assume that the specific heat capacity of the solution is also 4.184 J/g·K.
Therefore, the heat released or absorbed during the solution process is:
q_solution = 1.25 g x 4.184 J/g·K x 4.7 K = 24.8 J
Now we can use this value to calculate the heat of solution:
ΔH_solution = -q_solution / n
= -24.8 J / 8 mol
= -3.1 J/mol
Therefore, Note that the negative sign indicates that the solution process is exothermic, i.e., heat is released during the process.
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What is the mass of 0.850 mole of SO2?
Answers
Answer:
\(1 \: mole \: of \: sulphurdioxide \: weighs \: 64 \: g \\ 0.850 \: moles \: will \: weigh \: (0.850 \times 64) \: g \\ = 544 \: g\)
The mass of 0.85 mol of sulfur dioxide has been 54.4 grams.
Moles can be calculated as the ratio of the mass to the compound to the molecular mass. The moles can be expressed as:
Moles = \(\rm \dfrac{mass}{molecular\;mass}\)
Mass = moles \(\times\) molecular mass
The molecular mass of sulfur dioxide = Mass of sulfur + 2 \(\times\) mass of oxygen
= 32 + 2 \(\times\) 16
= 32 + 32
= 64 g/mol
The given moles of sulfur dioxide = 0.850 mol
The mass of sulfur dioxide = 0.850 \(\times\) 64
The mass of sulfur dioxide = 54.4 grams.
The mass of 0.85 mol of sulfur dioxide has been 54.4 grams.
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What is the total number of moles of hydrogen atoms contained in 1 mole of (NH4)2C2O4
Answers
Simplified formula
\(\\ \rm\Rrightarrow N_2H_8C_2O_4\)
Let's count atoms of all
N=2H=8C=2O_2In 1 mol of compound hydrogen is of
\(\\ \rm\Rrightarrow 8mols\)
Formula =>\( \sf N_2H_8C_2O_4\)
Now, Look at the number of hydrogen atoms..The number of hydrogen atoms is the number next to the symbol of Hydrogen i.e. H the number is H8.Thus, There are 8 moles of hydrogen in the compound!!~organic matter that has formed solid carbon structures while under high compression
Answers
The formation of these solid carbon structures from organic matter requires specific geological processes and conditions. High pressure, often in combination with high temperature.
Coal: Coal is a sedimentary rock composed primarily of carbonaceous material derived from the remains of plants. Over millions of years, layers of organic matter, such as dead plants and peat, undergo burial and are subjected to high pressure and heat. This process, known as coalification, results in the formation of solid carbon structures in the form of different coal ranks, ranging from lignite to bituminous and anthracite.
Graphite: Graphite is a crystalline form of carbon that occurs naturally. It is formed through the metamorphism of organic material, such as carbon-rich sediments or coal, at high temperatures and pressures. The process involves the rearrangement of carbon atoms into layered structures, resulting in the formation of graphite crystals with strong carbon-carbon bonds.
Diamonds: Diamonds are another example of solid carbon structures formed under high compression and temperature. They are derived from carbonaceous material located deep within the Earth's mantle. The intense pressure and temperature conditions cause the carbon atoms to arrange in a specific crystal lattice structure, resulting in the formation of diamond.
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given the cooling curve of one gram of a pure liquid, the length of the line bc depends on heating curve select one: a. the specific heat of the pure solid. b. the specific heat of the pure liquid. c. the heat of melting (or heat of fusion) of the pure substance. d. the melting point of the pure substance.
Answers
To answer this question, it is important to understand what a cooling curve represents. A cooling curve is a graphical representation of the temperature changes that occur in a pure liquid as it cools and solidifies. The curve shows the relationship between temperature and time, and it consists of several segments.
The length of the line bc on a cooling curve depends on the heating curve of the substance. The heating curve represents the relationship between temperature and heat energy required to raise the temperature of the substance from its solid state to its liquid state. Therefore, the correct answer is c. the heat of melting (or heat of fusion) of the pure substance.
The heat of melting is the amount of heat energy required to change a solid substance to a liquid state without changing its temperature. When a substance is heated, it absorbs heat energy, causing its temperature to increase until it reaches its melting point. At this point, the heat energy is used to overcome the attractive forces between the molecules of the substance, causing it to change from a solid to a liquid state. The length of line bc on a cooling curve represents the release of the heat of fusion as the substance solidifies.
In conclusion, the length of line bc on a cooling curve depends on the heat of melting of the pure substance, and the correct answer to the question is c. the heat of melting (or heat of fusion) of the pure substance. Answering this question requires a clear understanding of cooling curves and their relationship to heating curves.
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Esterification of propane 1,2,3-triol and unsaturated higher carboxylic acids will produce
Answers
Propan-1-ol and ethanoate are esterified Ethanoic acid and propan-1-ol combine to generate an ester. Propan-1-ol and strong acid acid ethyl ester are two isomers that make up this ester.
What byproducts of esterification are there?Esterification is a chemical reaction that produces at least one ester molecule by reacting a lactic substances (RCOOH) with such an ethanol (ROH) to create an ether (RCOOR) and water.
How is esterification rate determined?Up to around 1 moldm3, redox reactions are linked to [H+] concentration. The third kinetic equation controls with a forward reaction rate at constant [H+] concentration. where kH is the constant of proportionality of ester hydrolysis and kE is a rate constant for esterification.
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Maximum s-character is observed in
a) Triple bonded carbon atom b) Double bonded carbon atom
c) Single bonded carbon atom d) Carbon atom of benzene
Answers
\(\huge{\underline{\underline{\boxed{\sf{\purple{ǫᴜᴇsᴛɪᴏɴ}}}}}}\)
Maximum s-character is observed ina) Triple bonded carbon atom b) Double bonded carbon atomc) Single bonded carbon atomd) Carbon atom of benzene\(\huge{\underline{\underline{\boxed{\sf{\red{Answer}}}}}}\)
Maximum s-character is observed ina) Triple bonded carbon atomwhat 3 molecules are made from the process of cellular respiration?
Answers
Answer:
Hydrogen (H20), Carbon Dioxide (CO2), ATP
Which characteristic of a substance is considered a chemical property?
a.its boiling point
b.its reactivity
c.its density
d.its conductivity
Answers
Polyelectrolytes are typically used to separate oil and water in industrial applications. The separation process is dependent on controlling the pH. Fifteen (15) pH readings of wastewater following these processes were recorded. Is it reasonable to model these data using a normal distribution? 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 10.0 10.5 7.6 11.4 11.4 10.0 Yes, it passes the "fat pencil" test. Therefore, a normal distribution is a reasonable model. No, it does not pass the "fat pencil" test. Therefore, a normal distribution is not a reasonable model. O Yes, it passes the "fat pencil" test. Therefore, a normal distribution is not a reasonable model. O No, it does not pass the "fat pencil" test. Therefore, a normal distribution is a reasonable model.
Answers
No, it does not pass the "fat pencil" test. Therefore, a normal distribution is not a reasonable model. Option B is the correct answer.
The "fat pencil" test is a quick visual check to determine if a dataset can be reasonably approximated by a normal distribution. In this case, the pH readings of wastewater show a significant deviation from a normal distribution. The presence of several low pH values (1.0) and a few high pH values (10.0, 10.5, 11.4) indicate a non-normal distribution with skewness and potential outliers. Therefore, it is not reasonable to model these data using a normal distribution.
Option B is the correct answer.
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Why is a pyramid shape used to represent the energy in an Ecosystem?
Answers
Answer:
An energy pyramid shows the flow of energy at each trophic level in an ecosystem. A pyramid shape is used because energy is lost at each trophic level when organisms use it up.
Explanation:
Which of these elements is this group?
- Shiny & Solid at Room Temperature
- Atoms have 2 valence electrons
Lithium ,
Strontium
Silicon
Aluminum
Answers
Answer:
Strontium
Explanation:
In the periodic table, an element with two (2) valence electrons is found on group 2. Group 2 is a group of the periodic table that harbors element called ALKALINE EARTH METALS. As the name implies, they are metals that possess shiny and solid characteristics at room temperature.
Group 2 elements include the following: Beryllium (Be), Magnesium (Mg), Calcium (Ca), Strontium (Sr), barium (Ba), and radium (Ra). Based on the descriptive information in this question, the element being described is a GROUP 2 element. Based on the elements in the option, only STRONTIUM (Sr) is a group 2 element.
Which statement is true about matter?
a: all matter has volume
b: all matter has mass
c: both A and B.
d: all mater has either volume or mass but not both
Answers
Answer:
C
Explanation:
This is because matter is anything that has mass and occupies space.Therefore the space occupied by matter is volume
Can someone help
Me out pls if your good at chemistry
Answers
which pair of elements, when combined together, do not form covalent compound.
Answers
The two non metals
Which statement describes the periodic law?
Help please now!
Answers
Answer:
Answer is: elements in the same group have similar chemical properties. Periodic law is the arrangement of the elements in order of increasing atomic number.
Thermodynamics
How much energy does it take to melt 56.70g of water?
Answers
Answer:
18,937.8 J
Explanation:
A total of 334 J of energy are required to melt 1 g of ice at 0°C, which is called the latent heat of melting. At 0°C, liquid water has 334 J g−1 more energy than ice at the same temperature. This energy is released when the liquid water subsequently freezes, and it is called the latent heat of fusion.
A local hamburger shop sold a combined total of 620 hamburgers and cheeseburgers on Wednesday. There were 70 more cheeseburgers sold than hamburgers. How many hamburgers were sold on Wednesday?
Answers
The number of hamburgers sold on Wednesday is 275.
Let's assume the number of hamburgers sold is x.
According to the given information, the number of cheeseburgers sold is 70 more than the number of hamburgers. So, the number of cheeseburgers sold can be expressed as x + 70.
The total number of hamburgers and cheeseburgers sold is given as 620, so we can set up the following equation:
x + (x + 70) = 620
Combining like terms, we get:
2x + 70 = 620
Subtracting 70 from both sides of the equation:
2x = 550
Dividing both sides by 2:
x = 275
Therefore, the number of hamburgers sold on Wednesday is 275.
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The chemicals that are present before a reaction occurs are called _____, and the chemicals produced from the reaction are called _____.
Answers
Answer: Reactants-Products
Determine the molarity of a solution with a volume of 435. mL and 0.550 mol of solute dissolved.
Answers
Answer:
M = 1.26
Explanation:
Molarity = mole of solution/liters of solution
435mL/1000 = .435L
Plugging in the numbers into the formula, we get:
Molarity = .550 mol/.435L = 1.26 M