Answer:
8.279
Explanation:
The pH can be determined by hydrolysis of a conjugate base of weak acid at the equivalence point.
At the equivalence point, we have
[tex]$n_{NaOH}=n_{HNO_2}$[/tex]
= 25.00 x 0.200
= 5.00 m-mol
= 0.005 mol
Volume of the base that is added to reach the equivalence point is
[tex]$\frac{0.005}{1.00} \times 1000= 5.00 \ mL$[/tex]
Number of moles of [tex]$NO^-_{2}=n_{HNO_2}$[/tex]
= 0.005 mol
Volume at the equivalence point is 25 + 5 = 30.00 mL
Therefore, concentration of [tex]$NO^-_{2}= \frac{5}{30}$[/tex]
= 0.167 M
Now the ICE table :
[tex]$NO^-_2 + H_2O \rightarrow HNO_3 + OH^-$[/tex]
I (M) 0.167 0 0
C (M) -x +x +x
E (M) 0.167-x x x
Now, the value of the base dissociation constant is ,
[tex]$K_w=K_a \times K_b$[/tex] [tex]$(K_w \text{ is the ionic product of water })$[/tex]
[tex]$K_b =\frac{K_w}{K_a}$[/tex]
[tex]$K_b =\frac{1 \times 10^{-14}}{4.6 \times 10^{-4}}$[/tex]
= [tex]$2.174 \times 10^{-11}$[/tex]
Base ionization constant, [tex]$K_b = \frac{\left[HNO_2\right] \left[OH^- \right]}{\left[NO^-_2 \right]}$[/tex]
[tex]$2.174 \times 10^{-11}=\frac{x^2}{0.167 -x}$[/tex]
[tex]$x= 1.9054 \times 10^{-6}$[/tex]
So, [tex]$[OH^-]=1.9054 \times 10^{-6 } \ M$[/tex]
pOH =- [tex]$\log[OH^-]$[/tex]
= [tex]$- \log(1.9054 \times 10^{-6} \ M)$[/tex]
=5.72
Now, since pH + pOH = 14
pH = 14.00 - 5.72
= 8.279
Therefore the ph is 8.279 at the end of the titration.
Titration is a chemical process used to determine the concentration of an unknown sample from the known sample. At the equivalence point, the pH is 8.279.
What is the equivalence point?In titration, the point at which the titrant neutralizes the unknown analyte solution is called the equivalence point.
The moles of equivalence point of sodium hydroxide and nitrous acid are:
[tex]\begin{aligned}\rm n_{NaOH} &= \rm n _{HNO_{2}}\\\\&= 25.00 \times 0.200\\\\&= 0.005 \;\rm mol\end{aligned}[/tex]
The volume of the added base is 5.00 mL.
The moles of nitrogen dioxide are 0.005 moles and the volume at the equivalence point is 30 mL.
The molar concentration of nitrogen dioxide will be, 0.167 M.
From the ICE table, the base dissociation constant is calculated as:
[tex]\begin{aligned}\rm K_{w} &= \rm K_{a} \times K_{b}\\\\\rm K_{b} &= \dfrac{1 \times 10^{-14}}{4.6 \times 10^{-14}}\\\\&= 2.174 \times 10^{-11}\end{aligned}[/tex]
The ionization constant of the base is given as,
[tex]\begin{aligned}\rm K_{b} &= \rm \dfrac{[HNO_{2}][OH^{-}]}{[NO_{2}^{-}]}\\\\2.174 \times 10^{-11} &= \rm \dfrac{x^{2}}{0.167- x}\\\\&= 1.905 \times 10^{-6} \end{aligned}[/tex]
Now, pOH is calculated as:
[tex]\begin{aligned} \rm pOH &=\rm - log [OH^{-}]\\\\&= \rm -log (1.905 \times 10^{-6})\\\\&= 5.72\end{aligned}[/tex]
The pH of the titration is calculated as:
[tex]\begin{aligned} \rm pH + pOH &= 14\\\\\rm pH &= 14.00 - 5.72\\\\&= 8.279\end{aligned}[/tex]
Therefore the pH is 8.27.
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Resonance structures differ by ________.
A. placement of atoms only
B. placement of electrons only
C. number of atoms only
D. number of electrons only
E. number and placement of electrons
Answer:
b)
Explanation:
Resonance structure differ by placement of electrons only.
I hope you got the answer
♂️
During a tug of war competition neither team was able to gain an advantage which of the following explains the force is this situation
A. The forces are balanced
B.the forces are overcome by air friction
C.the mass of the rope cancels is the forces being exerted on it
D.the forces are unbalanced
Answer:
b i did the test
Explanation:
A solution of transferrin was titrated with a standard solution of Fe3+. The blank absorbance was 0.04, and the absorbance of 10.00 mL of the transferrin solution measured after adding 6.00 mL of titrant was 0.65. Calculate the corrected absorbance that should be plotted.
Answer:
The correct answer is 0.61.
Explanation:
Based on the given information, a transferrin solution was titrated with a standard ferric solution. The blank absorbance was 0.04 and the absorbance of 10 ml solution of transferrin post supplementation of 6 ml titrant came out to be 0.65. The corrected optical density or absorbance can be determined by using the formula,
Corrected OD = Measured OD - Blank or Reference OD
Now putting the values we get,
Corrected OD = 0.65 - 0.04
Corrected OD = 0.61
At higher temperatures, air can hold __vapor as compared to air at lower?
Answer:
water vapor
Explanation:
the the answer is water vapor
What is the pH of an aqueous solution made by combining 35.01 mL of a 0.3791 M ammonium chloride with 40.07 mL of a 0.3542 M solution of ammonia to which 3.112 mL of a 0.0896 M solution of HCI was added?
Answer:
pH = 9.25
Explanation:
Using H-H equation:
pH = pKa + log [A⁻] / [HA]
Where pH is pH of the buffer
pKa is pKa of the weak acid: 9.24
[A⁻] could be taken as moles of the conjugate base: Moles NH₃
[HA] moles of the weak acid: NH₄⁺
Initial moles of NH₃:
40.07mL = 0.04007L * (0.3542mol / L) = 0.01419mol
Initial moles NH₄⁺:
0.03501L * (0.3791mol / L) = 0.01327 mol
The HCl added reacts with NH₃ producing NH₄⁺:
HCl + NH₃ → NH₄⁺ + Cl⁻
Moles of HCl:
3.112x10⁻³L * (0.0896mol / L) = 0.00028 moles
That means moles of NH₃ and NH₄⁺ after the addition of HCl are:
NH₄⁺: 0.01327moles + 0.00028moles = 0.01355 moles
NH₃: 0.01419mol - 0.00028 moles = 0.01391 moles
pH of the buffer is:
pH = pKa + log [A⁻] / [HA]
pH = 9.24 + log [0.01391 moles] / [0.01355 moles]
pH = 9.25I have a buddy who recycles electronics, and isolates metals from the connector pins electrical boards. He isolates gold, for example, and purifies it the best he can, then sells it along with his other scrap metal. This last go around he was able to isolate 3.00 g of Au with a process he claims results in a 80.0% yield. If he is correct, what is his theoretical yield? In other words, he got 3.00 g, but what should he have been able to get?
Solution :
In the process to isolate gold that has a 80 percent yield, a 3.00 g of Au is being isolated.
That is, the actual yield of Au is 3. 00 g
Therefore, we need to find the theoretical yield.
As we know,
[tex]$\text{percent yield}=\frac{\text{actual yield}}{\text{theoretical yield}} \times 100$[/tex]
[tex]$\text{theoretical yield}=\frac{\text{actual yield}}{\text{present yield}} \times 100$[/tex]
As actual yield = 3.00 g
percent yield = 80 %
So, theoretical yield = [tex]$\frac{3.00}{80} \times 100$[/tex]
= 3.75 g
Thus he should be able to get 3.75 g which is the theoretical yield of Au.
A story to describe the motion on the graph
Question 20
Review
Which solution is the most concentrated?
1. 1 mole of solute dissolved in 1 liter of solution
2. 2 moles of solute dissolved in 3 liters of solution
3. 6 moles of solute dissolved in 4 liters of solution
4. 4 moles of solute dissolved in 8 liters of solution
Calculate the mass (in kg) of 4.87 x 10 25 atoms of Zn
Answer:
5.29kg
Explanation:
5.29kg
The mass of 4.87×10²⁵ atoms of Zn is 5.29 Kg
From Avogadro's hypothesis,
6.02×10²³ atoms = 1 mole of ZnRecall,
1 mole of Zn = 65.38 g
Converting 65.38 g to Kilogram (Kg), we have:
1000 g = 1 Kg
Therefore,
65.38 g = 65.38 / 1000
65.38 g = 0.06538 KgThus, we can say that,
6.02×10²³ atoms = 0.06538 Kg of ZnFinally, we shall determine the mass of Zn that contains 4.87×10²⁵ atoms. This can be obtained as follow:
6.02×10²³ atoms = 0.06538 Kg of Zn
4.87×10²⁵ atoms = [tex]\frac{4.87*10^{25} * 0.06538}{6.02*10^{23} } \\\\[/tex]
4.87×10²⁵ atoms = 5.29 Kg of ZnTherefore, the mass of 4.87×10²⁵ atoms of Zn is 5.29 Kg
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Na2CO3 + H2SO4 Na2SO4 + CO2 + H2O
=
Write the word equation for this reaction.
Answer:
that is an invalid question
The word equation for this reaction is:
Sodium carbonate + Sulfuric acid → Sodium sulfate + Carbon dioxide + Water.
The given chemical equation represents a chemical reaction between sodium carbonate (Na₂CO₃) and sulfuric acid (H₂SO₄). When these two substances react, they undergo a chemical change and produce different compounds. The reaction results in the formation of sodium sulfate (Na₂SO₄), carbon dioxide (CO₂), and water (H₂O).
In a word equation, the chemical reaction is described using the names of the substances involved rather than their chemical formulas. Hence, the word equation for this reaction would be:
Sodium carbonate + Sulfuric acid → Sodium sulfate + Carbon dioxide + Water.
This word equation provides a simple and concise description of the reactants and products involved in the chemical reaction, allowing for a better understanding of the overall transformation of substances that occurs during the reaction.
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which of the following elements has the smallest atomic radius?
Answer:
helium is the smallest element and francium is the largest
Answer:
K+ is the right answer
Explanation:
Calculate the work (w) and ΔEo, in kJ, at 298 K and 1 atm pressure, for the combustion of one mole of C4H10 (g). First write and balance the equation. The products will be CO2 (g) and H2O (g)
The value of ΔHo for this reaction is -2658.3 kJ/mol
Answer:
Explanation:
2C₄H₁₀ + 13O₂ = 8 CO₂ + 10H₂O
Change in number of moles Δn = 18 - 15 = + 3 moles .
ΔHo = -2658.3 kJ/mol.
ΔHo = ΔEo+ Δn RT
Δn = 3
For one mole Δn = 1.5
ΔHo = ΔEo+ W
W = Δn RT
= 1.5 x 8.31 x 298
= 3714.5 J
= 3.7 kJ /mole
ΔHo = ΔEo+ W
ΔEo = ΔHo - W
= -2658.3 - 3.7 kJ
= - 2662 kJ .
(a) The work done for the combustion of 1 mole of methane is 3,714.5 J.
(b) The change in the energy of the given system is -3,991.2 kJ.
The balanced chemical reaction of the given compounds is written as follows;
[tex]2C_4H_{10} \ + \ 13O_2 \ -->\ 8CO_2 \ + \ 10H_2 O[/tex]
The change in number of moles;
[tex]\Delta n = 18 - 15 = 3[/tex]
The work done for the combustion of 1 mole of methane is calculated as follows;
[tex]W = \frac{\Delta n}{2} RT\\\\W = \frac{3}{2} \times 8.31 \times 298\\\\W = 3,714.6 \ J[/tex]
The energy change is calculated as follows;
[tex]\Delta E_0 = \Delta H_o - W\\\\\Delta E_0 = (\frac{3 \ mole}{2} \times-2658.3 \ kJ/mol) - 3.715 \ kJ\\\\\Delta E_0 = -3,991.2 \ kJ[/tex]
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Joints in train tracks are designed with extra space to allow for __________________ in hot weather.
Join in tracks are designed with extra space to allow for friction in hot weather
Answer:
Joints in train tracks are designed with extra space to allow for expansion and contraction of the track material in hot weather.
how does fire start
The reaction of 11.9 g of CHCl3 with excess chlorine produced 11 grams of CCl4, carbon tetrachloride. What is the percent yield
Which of these is purposefully changed during a scientific investigation?
Answer:
The independent variable is the variable that is deliberately changed by the scientist. The dependent variable is the one observed during the experiment. The dependent variable is the data we collect during the experiment.
Which of these describes a chemical property? A. the color of the substance B. the hardness of the substance C.how the substance behaves in the presence of an acid D. how the substance behaves in the presence of a magnet
Answer:
C. How the substance behaves in the presence of an acid.
Explanation:
Have a great day
Chemical properties can be defined as the ones that describe a substance's ability to undergo chemical changes.
Physical properties can be defined as the ones that are measured and observed without actually changing the substance's identity.
Among the given options, the color, the hardness, and the behavior of a substance in the presence of a magnet are all examples of physical properties.
However, the behavior of a substance in the presence of an acid is an example of chemical property.
Hence, the correct answer is option c.
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Find the mass of benzene (C6H6) required to produce 2.66 g of carbon dioxide gas from the reaction described by the following equation:
2C6H6 + 15O2 → 6H2O + 12CO2
Answer:
Mass of benzene required = 0.78 g
Explanation:
Given data:
Mass of CO₂ produced = 2.66 g
Mass of benzene required = ?
Solution:
Chemical equation:
2C₆H₆ + 15O₂ → 6H₂O + 12CO₂
Number of moles of CO₂:
Number of moles = mass/molar mass
Number of moles = 2.66 g/ 44 g/mol
Number of moles = 0.06 mol
Now we will compare the moles of CO₂ with C₆H₆.
CO₂ : C₆H₆
12 : 2
0.06 : 2/12×0.06=0.01 mol
Mass of benzene required:
Mass = number of moles × molar mass
Mass = 0.01 mol × 78.11 g/mol
Mass = 0.78 g
The transition metals are all group together on the periodic table all the following explains this grouping except?
A) They all have good conductivity
B) they are not found in nature as pure elements
C)they are used in construction and electrical applications
D) they are less reactive than elements in groups 1 and 2
HELPP ANSWERSSS!!!!
Which of the following elements in Group 13 would most likely have a physical and chemical properties of brittle, shiny, semiconductor, and is silver?
A.
Indium
B.
Gallium
C.
Aluminum
D.
Boron
Answer:
answer is
Explanation:
Gallium because it has the properties which you have mentioned
The element of Group 13 would most likely have a physical and chemical properties of brittle, shiny, semiconductor, and is silver is gallium. The correct option is B.
What is gallium?Gallium is a chemical substance with the atomic number 31 and indeed the emblem Ga.
Gallium belongs to periodic table group 13 and is chemically similar to the other metals in the group. In standard temperature and pressure, gallium is a soft, silvery metal.
It finds widespread application in Blu-ray technology, mobile phones, blue and green LEDs, and pressure sensors for touch switches. Gallium readily alloys with the majority of metals.
It is especially useful in low-melting alloys. Because of its high boiling point, it is ideal for recording temperatures that would vaporize a thermometer.
Gallium is a rare element on Earth, but its abundance is comparable to that of lithium and lead, with a content of 19 ppm in the continental crust.
Thus, the correct option is B.
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Which of the following is NOT something that electromagnetic waves and mechanical waves have in common?
A.Both can transmit energy through a medium.
B.Both involve the repeated vibrations of particles
.C.Neither of the waves can move matter.
D.In both, vibrations occur in a parallel direction to the direction of the wave.
Answer:
D. In both, vibrations occur in a parallel direction to the direction of the wave.
Explanation:
It is not true that in both mechanical and electromagnetic waves, vibrations occur in parallel direction to the direction of the wave.
As with all waves, they are disturbances that transfers energy without moving the materials of the medium.
Electromagnetic waves have only one way of propagation which is a vibration in both parallel and longitudinal direction.Mechanical waves can be propagated either in a parallel direction or longitudinal direction and not both.A 31.4 mL sample of nitrogen gas was collected over water at 23.7°C and a total pressure of 706 torr. What mass of nitrogen gas was collected
Answer:
[tex]m=0.0325g[/tex]
Explanation:
Hello!
In this case, since the collection of gases over at certain conditions implies the usage of the ideal gas equation and computation of the pressure of the gas by subtracting the vapor pressure of water (21.7 torr at 23.7 °C) to the total pressure as shown below:
[tex]p_N=706-21.7=684.3torr =0.900atm[/tex]
Next step is to compute the moles of nitrogen at the given conditions:
[tex]n=\frac{PV}{RT}=\frac{0.900atm*0.0314L}{0.08206\frac{atm*L}{mol*K}*296.85K} \\\\n=0.00116mol[/tex]
Final step is to compute the mass by knowing that gaseous nitrogen has a molar mass of 28.02 g/mol:
[tex]m=0.00116mol*\frac{28.02g}{1mol} \\\\m=0.0325g[/tex]
Regards!
The mass of nitrogen gas that was collected is 0.0336 grams.
Given the following data:
Volume of nitrogen gas = 31.4 mLTemperature = 23.7°C to K = 296.7 KelvinPressure = 706 torr to atm = 0.93 atm.Scientific data:
Ideal gas constant, R = 0.0821 L⋅atm/mol⋅KMolar mass of nitrogen gas = 28.02 g/molTo determine the mass of nitrogen gas that was collected:
First of all, we would calculate the number of moles of nitrogen gas used by using the ideal gas law equation:
[tex]n = \frac{PV}{RT}[/tex]
Where;
P is the pressure. V is the volume. n is the number of moles of gas. R is the ideal gas constant. T is the temperature.Substituting the given parameters into the formula, we have;
[tex]n = \frac{0.93 \times 0.0314}{0.0821 \times 296.7}\\\\n=\frac{0.0292}{24.36}[/tex]
n = 0.001199 moles
For the mass of nitrogen gas:
[tex]Mass = n \times molar \;mass\\\\Mass = 0.001199 \times 28.02[/tex]
Mass = 0.0336 grams
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Discuss the differences expected in the IR spectra of methyl benzoate vs methyl m-nitrobenzoate.
Answer:
im sorry but i havent reached that topic as of yet
Explanation:
What is the carbon cycle? ASAP
Answer:
The carbon cycle is the biogeochemical cycle by which carbon is exchanged among the biosphere, pedosphere, geosphere, hydrosphere, and atmosphere of the Earth. Carbon is the main component of biological compounds as well as a major component of many minerals such as limestone
What do the flames below the pot
represent
Answer:
That it is cooking the food or whatever you have in the pot.
Explanation:
We are learning this in science.
Which of the following would lose heat the fastest?
15 grams of water
200 grams of water
1000 grams of water
500 grams of water
Answer:
15 grams of water
Explanation:
15 grams of water of water would lose heat the faster compared to higher masses of water.
Water generally is a poor conductor heat.
To heat up a unit of water, significant amount of energy must be added to the body of water. With time, the body continues to increase in temperature. A 500g mass of water will take more time to lose heat.As the thermal energy of matter increases, its particles usually spread out, causing
Answer:
As the thermal energy of matter increases, its particles usually spread out, causing the substance to expand.
Explanation:
i have a book about this stuff
As the thermal energy of matter increases, its particles usually spread out,
causing the substance to expand.
What is Thermal energy?Thermal energy is the energy which is measured as a result of its heat
content. This is usually as a result of the increase in temperature of the
substance involved.
Increase in temperature leads to an increase in thermal energy. This leads
to the particles spreading out and the substance expanding as a result of
the atoms being loosely held together.
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What is the numerical value for the standard cell potential of the following reaction?
2Cr2(aq) + 3Cu(s) → 2Cro) + 3Cu2+ (aq)
a) -1.25 V
b) -0.57 V
c) +0.57 V
d) +1.25 V
What is the concentration (M) of a NaCl solution prepared by dissolving 9.1 g of NaCl in sufficient water to give 375 mL of solution?
Answer:
d
Explanation:
Formula for cesium iodide
Answer:
Csl
Explanation:
Caesium iodide or cesium iodide is the ionic compound of caesium and iodine. It is often used as the input phosphor of an X-ray image intensifier tube found in fluoroscopy equipment. Caesium iodide photocathodes are highly efficient at extreme ultraviolet wavelengths.
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