What mass of precipitate (in g) is formed when 250.0 mL of 0.150 M CuCl₂ is mixed with excess KOH in the following chemical reaction?
CuCl₂(aq) + 2 KOH(aq) → Cu(OH)₂(s) + 2 KCl(aq)

Answer:

Four common types of reactions involving carbonyl reactions: 1) nucleophilic addition; 2) nucleophilic acyl substitution; 3) alpha substitution; 4) carbonyl condensations. The first two were previously discussed and the second two involve the properties of the carbon directly adjacent to the carbonyls, α carbons.

Alpha-substitution reactions results in the replacement of an H attached to the alpha carbon with an electrophile.  

The nucleophile in these reactions are new and called enols and enolates.

Explanation:

The carbon in the carbonyl is the reference point and the alpha carbon is adjacent to the carbonyl carbon.  

Hydrogen atoms attached the these carbons denoted with Greek letters will have the same designation, so an alpha hydrogen is attached to an alpha carbon.  

Aldehyde hydrogens not given Greek leters.  

α hydrogens display unusual acidity, due to the resonance stabilization of the carbanion conjugate base, called an enolate.  

Tautomers are readily interconverted constitutional isomers, usually distinguished by a different location for an atom or a group, which is different than resonance.  

The tautomerization in this chapter focuses on the carbonyl group with alpha hydrogen, which undergo keto-enol tautomerism.  

Keto refers to the tautomer containing the carbonyl while enol implies a double bond and a hydroxyl group present in the tautomer.  

The keto-enol tautomerization equilibrium is dependent on stabilization factors of both the keto tautomer and the enol tautomer, though the keto form is typically favored for simple carbonyl compounds.  

The 1,3 arrangement of two carbonyl groups can work synergistically to stabilize the enol tautomer, increasing the amount present at equilibrium.

The positioning of the carbonyl groups in the 1,3 arrangement allows for the formation of a stabilizing intramolecular hydrogen bond between the hydroxyl group of the enol and the carbonyl oxygen as well as the alkene group of the enol tautomer is also conjugated with the carbonyl double bond which provides additional stabilization.

Aromaticity can also stabilize the enol tautomer over the keto tautomer.

Under neutral conditions, the tautomerization is slow, but both acid and base catalysts can be utilized to speed the reaction up.  

Biological enol forming reactions use isomerase enzymes to catalyze the shifting of a carbonyl group in sugar molecules, often converting between a ketose and an aldose in a process called carbonyl isomerization.

Answer:

Using the Iodoform test, we can differentiate both compounds.

Explanation:

Benzaldehyde (C6H5CHO -an aldehyde) and Acetophenone (C6H5COCH3 - a methyl ketone) can be differentiated by reacting both compounds with iodine in a basic (NaOH) solutions.

The methyl ketone (acetophenone) gives a pale yellow precipitate of triiodomethane (iodoform) while the aldehyde (benzaldehyde) would not react.

This is known as the IODOFORM test and is indicative for methyl ketones

Answer:

Theoretical yield of 1-Phenyl-1-propanol in grams = 0.871 g

Explanation:

A Grignard reagent is any of the numerous organic derivatives of magnesium (Mg) which are commonly represented by the general formula RMgX (where R is a hydrocarbon radical e.g. methyl, ethyl, propyl, etc.; and X is a halogen atom, e.g. chlorine, bromine, or iodine)

A Grignard reaction converts an aldehyde to a secondary alcohol. In the grignard reaction involving benzaldehyde as in this experiment, the grignard reagent used is ethyl magnesium bromide, EtMgBr, and the resulting product is 1-Phenyl-1-propanol, a secondary alcohol. The reaction is shown in the figure attached below.

Mass of benzaldehyde in 0.650 mL = density × volume

Density of Benzaldehyde = 1.044 g/mL

Mass of benzaldehyde = 1.044 g/mL × 0.650 mL = 0.6786 g

Molar mass of benzaldehyde = 106 g/mol

Molar mass of 1-Phenyl-1-propanol = 136 g/mol

Mass of = mass of benzaldehyde × mole ratio of 1-Phenyl-1-propanol and benzaldehyde

Mass of 1-Phenyl-1-propanol = 0.6786 g × (136 g/mol)/(106 g/mol) = 0.871 g

Therefore, the theoretical yield of 1-Phenyl-1-propanol in grams = 0.871 g

Answer:

[tex]d=4.24x10^{-4}\frac{lb}{in^3}[/tex]

Explanation:

Hello there!

In this case, according to the given information, it turns out firstly necessary for us to set the equation for the calculation of density and mass divided by volume:

[tex]d=\frac{m}{V}[/tex]

Thus, we can find the mass of the unknown by subtracting the total mass of the liquid to the mass of the flask and the liquid:

[tex]m=552.4g-464.7g=87.7g[/tex]

So that we are now able to calculate the density in g/mL first:

[tex]d=\frac{87.7g}{27.8mL}=3.15g/mL[/tex]

Now, we proceed to the conversion to lb/in³ by using the following setup:

[tex]d=3.15\frac{g}{mL}*\frac{1lb}{453.6g}*\frac{1in^3}{16.3871mL}\\\\d=4.24x10^{-4}\frac{lb}{in^3}[/tex]

Regards!

Answer:

[tex]\%m/m=76.1\%[/tex]

Explanation:

¡Hola!

En este caso, considerando la información dada, entendemos que se haría primero necesario calcular el volumen del cono en metros cúbicos, teniendo en cuenta que 0.005 km son 5 m y 300 cm son 3 m:

[tex]V=\frac{1}{3} \pi r^2h\\\\V=\frac{1}{3} \pi *(5m)^2(3m)=78.5m^3\\\\[/tex]

Ahora, convertimos esta cantidad a gramos por medio de la densidad para conocer la masa de la solución:

[tex]m_{sol}=78.5m^3*\frac{1.2g}{1m^3} =94.2g[/tex]

Finalmente, aplicamos la definición de %m/m para obtener:

[tex]\%m/m=\frac{300g}{300g+94.2g}*100\%\\\\ \%m/m=76.1\%[/tex]

¡Saludos!

Answer:

[tex]V_2= 736mL[/tex]

Explanation:

Hello there!

In this case, according to the given information, it turns out possible for us to solve this problem by using the combined gas law:

[tex]\frac{P_2V_2}{T_2}= \frac{P_1V_1}{T_1}[/tex]

Thus, we solve for the final volume by solving for V2 as follows:

[tex]V_2= \frac{P_1V_1T_2}{T_1P_2}[/tex]

Now, we plug in the variables to obtain the result in milliliters and making sure we have both temperatures in Kelvins:

[tex]V_2= \frac{1.20atm*735mL*279K}{(112+273)K*660/760atm}\\\\V_2= \frac{1.20atm*735mL*279K}{(112+273)K*660/760atm}=736mL[/tex]

Regards!

Answer:

0.000000000000000969 atm

Explanation:

Based on the reaction:

CO(g) + Cl2(g) ⇄ COCl2(g)

Where equilibrium constant, Kp, is defined as:

Kp = 1.49x10⁻⁸ = PCOCl2 / PCO * PCl2

As PCO = PCl2 = 2.55x10⁻⁴atm:

1.49x10⁻⁸ = PCOCl2 / PCO * PCl2

1.49x10⁻⁸ = PCOCl2 / 2.55x10⁻⁴atm * 2.55x10⁻⁴atm

9,69x10⁻¹⁶atm = PCOCl2

In decimal form:

Answer:

The amount of work done on the system is 18234 J and the final positive sign means that this work corresponds to an increase in internal energy of the gas.

Explanation:

Thermodynamic work is called the transfer of energy between the system and the environment by methods that do not depend on the difference in temperatures between the two. When a system is compressed or expanded, a thermodynamic work is produced which is called pressure-volume work (p - v).

The pressure-volume work done by a system that compresses or expands at constant pressure is given by the expression:

W system= -p*∆V

Where:

In this case:

Replacing:

W system= -1.013*10⁶ Pa* (-0.018 m³)

Solving:

W system= 18234 J

The amount of work done on the system is 18234 J and the final positive sign means that this work corresponds to an increase in internal energy of the gas.

The process of watering the crops is called irrigation.

Any two methods of irrigation are:

This system is used on the uneven land where less water is available. The perpendicular pipes, having rotating nozzles on top, are joined to the main pipeline at regular intervals. Water is allowed to flow through main pipe under pressure, which escapes from the rotating nozzles. In this way water gets sprinkled on the crop.

This system is used to save water as it allows the water to flow drop by drop at the roots of the plants. It is the best technique for watering fruit plants, gardens and trees. Water is not wasted at all.

Answer:

3) About 0.35 grams of hydrogen gas.

4) About 65.2 grams of aluminum oxide.

Explanation:

Question 3)

We are given that 7.9 grams of sodium is dropped into a bathtub of water, and we want to determine how many grams of hydrogen gas is released.

Since sodium is higher than hydrogen on the activity series, sodium will replace hydrogen in a single-replacement reaction for sodium oxide. Hence, our equation is:

[tex]\displaystyle \text{Na} + \text{H$_2$O}\rightarrow \text{Na$_2$O}+\text{H$_2$}[/tex]

To balance it, we can simply add another sodium atom on the left. Hence:

[tex]\displaystyle 2\text{Na} + \text{H$_2$O}\rightarrow \text{Na$_2$O}+\text{H$_2$}[/tex]

To convert from grams of sodium to grams of hydrogen gas, we can convert from sodium to moles of sodium, use the mole ratios to find moles in hydrogen gas, and then use hydrogen's molar mass to find its amount in grams.

The molar mass of sodium is 22.990 g/mol. Hence:

[tex]\displaystyle \frac{1\text{ mol Na}}{22.990 \text{ g Na}}[/tex]

From the chemical equation, we can see that two moles of sodium produce one mole of hydrogen gas. Hence:

[tex]\displaystyle \frac{1\text{ mol H$_2$}}{2\text{ mol Na}}[/tex]

And the molar mass of hydrogen gas is 2.016 g/mol. Hence:

[tex]\displaystyle \frac{2.016\text{ g H$_2$}}{1\text{ mol H$_2$}}[/tex]

Given the initial value and the above ratios, this yields:

[tex]\displaystyle 7.9\text{ g Na}\cdot \displaystyle \frac{1\text{ mol Na}}{22.990 \text{ g Na}}\cdot \displaystyle \frac{1\text{ mol H$_2$}}{2\text{ mol Na}}\cdot \displaystyle \frac{2.016\text{ g H$_2$}}{1\text{ mol H$_2$}}[/tex]

Cancel like units:

[tex]=\displaystyle 7.9\cdot \displaystyle \frac{1}{22.990}\cdot \displaystyle \frac{1}{2}\cdot \displaystyle \frac{2.016\text{ g H$_2$}}{1}[/tex]

Multiply. Hence:

[tex]=0.3463...\text{ g H$_2$}[/tex]

Since we should have two significant values:

[tex]=0.35\text{ g H$_2$}[/tex]

So, about 0.35 grams of hydrogen gas will be released.

Question 4)

Excess oxygen gas is added to 34.5 grams of aluminum and produces aluminum oxide. Hence, our chemical equation is:

[tex]\displaystyle \text{O$_2$} + \text{Al} \rightarrow \text{Al$_2$O$_3$}[/tex]

To balance this, we can place a three in front of the oxygen, four in front of aluminum, and two in front of aluminum oxide. Hence:

[tex]\displaystyle3\text{O$_2$} + 4\text{Al} \rightarrow 2\text{Al$_2$O$_3$}[/tex]

To convert from grams of aluminum to grams of aluminum oxide, we can convert aluminum to moles, use the mole ratios to find the moles of aluminum oxide, and then use its molar mass to determine the amount of grams.

The molar mass of aluminum is 26.982 g/mol. Thus:

[tex]\displaystyle \frac{1\text{ mol Al}}{26.982 \text{ g Al}}[/tex]

According to the equation, four moles of aluminum produces two moles of aluminum oxide. Hence:

[tex]\displaystyle \frac{2\text{ mol Al$_2$O$_3$}}{4\text{ mol Al}}[/tex]

And the molar mass of aluminum oxide is 101.961 g/mol. Hence: [tex]\displaystyle \frac{101.961\text{ g Al$_2$O$_3$}}{1\text{ mol Al$_2$O$_3$}}[/tex]

Using the given value and the above ratios, we acquire:

[tex]\displaystyle 34.5\text{ g Al}\cdot \displaystyle \frac{1\text{ mol Al}}{26.982 \text{ g Al}}\cdot \displaystyle \frac{2\text{ mol Al$_2$O$_3$}}{4\text{ mol Al}}\cdot \displaystyle \frac{101.961\text{ g Al$_2$O$_3$}}{1\text{ mol Al$_2$O$_3$}}[/tex]

Cancel like units:

[tex]\displaystyle= \displaystyle 34.5\cdot \displaystyle \frac{1}{26.982}\cdot \displaystyle \frac{2}{4}\cdot \displaystyle \frac{101.961\text{ g Al$_2$O$_3$}}{1}[/tex]

Multiply:

[tex]\displaystyle = 65.1852... \text{ g Al$_2$O$_3$}[/tex]

Since the resulting value should have three significant figures:

[tex]\displaystyle = 65.2 \text{ g Al$_2$O$_3$}[/tex]

So, approximately 65.2 grams of aluminum oxide is produced.

Answer:

Solution given:

3.

[tex]2Na+H_2O→Na _2O+H_2[/tex]

2Na=2*23g.

2O=18g.

[tex]Na_2O[/tex]=62g

[tex]H_2[/tex]=2 g

we have

2*23g of Na produce 2g of [tex]H_2[/tex]

Now

7.9 g of Na produce 2*7.9/(2*23)

=0.34g of [tex]H_2[/tex]

4.

we have

[tex]3O_2+4Al→2Al_2O_3[/tex]

[tex]3O_2[/tex]=3*16g*2g

4Al=4*27g

[tex]2Al_2O[/tex]= 2*27*2g+2*16*3g

4*27g of Al produces 204g of [tex]Al_2O_3[/tex]

34.5g of Al produces 204g*34.5/(4*27)

Answer:

See explanation

Explanation:

Isomers are molecules which have the same molecular formula but different structural formulas. Sometimes, isomers may even contain different functional groups.

The formula C2H6O may refer to an ether or an alcohol. The compound could be CH3CH2OH(ethanol) or CH3OCH3(methoxymethane).

Hence, the functional isomers of the formula C2H6O are ethanol and methoxymethane.

Answer:

Following are the solution to the given question:

Explanation:

In the aqueous solution of [tex]Hg^{2+}[/tex] ion is used to represent a [tex][Hg(H_2O)_4]^{2+}[/tex].

It is used to form a complex with iodide ions as [tex][Hgl_4]^{2-}[/tex].  

Conversion reaction:

[tex][Hg(H_2O)_4]^{2+} +4I^{-} \to [HgI_4]^{2-}+4H_20[/tex]

Following are the formation constants:

[tex]k_f=\frac{[HgI_4]^{2-}}{[Hg(H_2O)_4]^{2+} [I^{-}]^4}[/tex]

Following are the first step to the conversion:  

[tex][Hg(H_2O)_4]^{2+} +I^{-} \to [HgI(H_2O)_3]^{+}+H_20[/tex]

Answer:

The rate of the forward reaction equals the rate of the reverse reaction.

Explanation:

To know which option is correct, it important that we know what dynamic equilibrium is all about.

We'll begin by defining chemical equilibrium.

A chemical system is said to be in chemical equilibrium when there is no observable change in the properperties of the chemical system.

Dynamic equilibrium on the other hand can be defined as a state in which the forward and backward reaction is occurring at the same time. Thus, in dynamic equilibrium, the rate of the forward reaction is equal to the rate of the backward (i.e reverse) reaction.

Answer:

2.25 M

Explanation:

The reaction that takes place is:

First we calculate how many potassium iodide moles reacted, using the given volume and concentration:

Then we convert 45 mmoles of KI into mmoles of Pb(NO₂)₃, using the stoichiometric coefficients of the balanced reaction:

Finally we calculate the molarity of the Pb(NO₂)₃ solution, using the calculated number of moles and given volume:

Answer:

Cu+(aq)--->Cu2+(aq) + e- : oxidation

reason: there is loss of electrons.

I2(s) + 2e--->2I-(aq) : reduction

reason: There is reduction of electrons.

Answer:

The correct answer is - 83. torr

Explanation:

We know that:

p = X solvent * P pure solvent,

where, X solvent = number of moles of solvent / total number of moles.

in this solution, solute is 10.9 g of C12 H10 and the solvent is 25.3 g C6H6.  

molar mass of C6H6 = 6 * 12 g/mol + 6 * 1g/mol = 78 g/mol ( =>  moles of solvent = mass in grams / molar mass)

moles of solvent = 25.3 g / 78 g/mol = 0.3243 mol

molar mass of C12H10 = 12 * 12g/mol + 10*1g/mol = 154 g/mol

moles of solute = 10.9 g / 154 g/mol = 0.07077 mol

=> X solvent = 0.3243 / (0.3243 + 0.07077) = 0.8208

=> p = 0.8208 * 100.84 torr = 82.77 torr ≈ 83.0 torr

Answer: 83.0 torr

Answer:

725.15 L

Explanation:

The balanced chemical equation for the reaction between Na₂O₂ and CO₂ is the following:

Na₂O₂ + CO₂ → Na₂CO₃ + 1/2 O₂

From the stoichiometry of the reaction, 1 mol of Na₂O₂ reacts with 1 mol CO₂. So, the stoichiometric ratio is 1 mol Na₂O₂/1 CO₂.

Now, we convert the mass of reactants to moles by using the molecular weight (Mw) of each compound:

Mw (Na₂O₂) = (23 g/mol x 2) + (16 g/mol x 2) = 78 g/mol

moles Na₂O₂ = 96.7 g/(78 g/mol) = 1.24 mol Na₂O₂

Mw (CO₂) = 12 g/mol + (16 g/mol x 2) = 44 g/mol

moles CO₂ = 0.0755 g/(44 g/mol) = 1.71 x 10⁻³ mol CO₂

Now, we calculate the number of moles of CO₂ we need to completely react with the mass of Na₂O₂ we have:

1.24 mol Na₂O₂ x 1 mol CO₂/1 mol Na₂O₂ = 1.24 mol CO₂

In 1 L of respired air we have 1.71 x 10⁻³ mol CO₂ (0.0755 g), so we need the following number of liters to have 1.24 mol of CO₂:

1.24 mol CO₂ x 1 L/1.71 x 10⁻³ mol CO₂ = 725.15 L

Answer:

320 L

Explanation:

We'll begin by calculating the number of mole in 80.7 g of C₂SO₄. This can be obtained as follow:

Mass of C₂SO₄ = 80.7 g

Molar mass of C₂SO₄ = (12×2) + 32 + (16×4)

= 24 + 32 + 64

= 120 g/mol

Mole of C₂SO₄ =?

Mole = mass /molar mass

Mole of C₂SO₄ = 80.7 / 120

Mole of C₂SO₄ = 0.6725 mole

Finally, we shall determine the volume. This can be obtained as follow:

Mole of C₂SO₄ = 0.6725 mole

Molarity = 0.0021 M

Volume =?

Molarity = mole / Volume

0.0021 = 0.6725 / Volume

Cross multiply

0.0021 × Volume = 0.6725

Divide both side by 0.0021

Volume = 0.6725 / 0.0021

Volume ≈ 320 L

Thus, the volume that can be prepared is approximately 320 L.

Answer:

The correct approach is "12.25°C".

Explanation:

Given:

Mass of lead,

mc = 245 g

Initial temperature,

tc = 300°C

Mass of Aluminum,

ma = 150 g

Initial temperature,

ta = 12.0°C

Mass of water,

mw = 820 g

Initial temperature,

tw = 12.0°C

Now,

The heat received in equivalent to heat given by copper.

The quantity of heat = [tex]m\times s\times t \ J[/tex]

then,

⇒ [tex]245\times .013\times (300-T) = 150\times .9\times (T-12.0) + 820\times 4.2\times (T-12.0)[/tex]

⇒             [tex]3.185(300-T) = 135(T-12.0) + 3444(T-12.0)[/tex]

⇒             [tex]955.5-3.185T=135T-1620+3444T-41328[/tex]

⇒                         [tex]43903.5 = 3582.185 T[/tex]

⇒                                  [tex]T = 12.25^{\circ} C[/tex]

Answer:

1.27 × 10⁵ L

Explanation:

Step 1: Given data

Step 2: Convert the temperatures to the Kelvin scale

We will use the following expression.

K = °C + 273.15

K = 21 °C + 273.15 = 294 K

K = -48 °C + 273.15 = 225 K

Step 3: Calculate the final volume of the balloon

We will use the combined gas law.

P₁ × V₁ / T₁ = P₂ × V₂ / T₂

V₂ = P₁ × V₁ × T₂/ T₁ × P₂

V₂ = 745 Torr × 1.41 × 10⁴ L × 225 K/ 294 K × 63.1 Torr

V₂ = 1.27 × 10⁵ L

Answer:

London dispersion forces (LDF)

Explanation:

I had a test about this, so it should be right. Good Luck :D

Answer:

Measure liquid by aligning the meniscus with the volume line.

Explanation:

A pipette is an instrument specially made for measuring a small volume of liquid.

The pipette comes in various sizes to be used in measuring various volumes of liquid. Generally, the pipette has a volume line which helps us to measure a liquid.

A liquid is measured by aligning the meniscus with the volume line.

Answer:

The correct solution is "3.28 m".

Explanation:

According to the question,

Mol fraction of solvent,

= 0.0558

Molar mass of water,

= 18 g/mol

Mol of H₂O in 1000 g water,

= 55.55 mol

Now,

Let the mol of solute will be "x mol".

Total mol in solution will be "55.55 + x".

As we know,

⇒ The mol fraction of solvent = [tex]\frac{x}{55.55+x}[/tex]

                                        [tex]0.0558=\frac{x}{55.55+x}[/tex]

                                                [tex]x=0.0558[55.55+x][/tex]

                                                [tex]x=3.09969+0.0558x[/tex]

                               [tex]x-0.0558x=3.09969[/tex]

                                               [tex]x=\frac{3.09969}{0.9442}[/tex]

                                                  [tex]=3.38 \ m[/tex]

Answer:

Following are the response to the given question:

Explanation:

The number of shells

n = 4

Calculating the spectral line:

[tex]= \frac{n(n-1)}{2}\\\\ = \frac{4(4-1)}{2} \\\\= \frac{4\times 3}{2}\\\\ = \frac{12}{2}\\\\ = 6[/tex]

Answer:

1. 26.30 g C.

2. 4.42 g H.

3. 35.04 g O.

Explanation:

Hello there!

In this case, according to the given information, it turns out possible for us to calculate the required as follows:

1. Here, the only source of carbon is in CO2, and thus, we calculate the grams of carbon from the produced grams of this substance:

[tex]m_C=96.38gCO_2*\frac{1molCO_2}{44.01gCO_2} *\frac{1molC}{1molO_2} *\frac{12.01gC}{1molC} =26.30g[/tex]

2. Here, the only source of hydrogen is in H2O, and thus, we calculate the grams of hydrogen from the produced grams of this substance:

[tex]m_H=39.46gH_2O*\frac{1molH_2O}{18.02gH_2O} *\frac{2molH}{1molH_2O} *\frac{1.01gH}{1molH} =4.42gH[/tex]

3. Here, we subtract the mass of H and C from the mass of the sample, to obtain the mass of oxygen:

[tex]m_O=65.76g-26.30g-4.42g\\\\m_O=35.04g[/tex]

Regards!

Answer:

no

Explanation:

Fluoride is not nucleophilic (having the tendency to donate electrons) enough to allow for the use of HF to cleave ethers in protic media(protic solvents are polar liquid compounds that have dissociable hydrogen atoms). The rate of reaction is comparably low, so that heating of the reaction mixture is required.

Answer:

Pressure, P = 67.57 atm

Explanation:

Given the following data;

Conversion:

We would convert the value of the temperature in Celsius to Kelvin.

T = 273 + °C

T = 273 + 159

T = 432 Kelvin

To find the pressure of the gas, we would use the ideal gas law;

PV = nRT

Where;

Making P the subject of formula, we have;

[tex] P = \frac {nRT}{V} [/tex]

Substituting into the formula, we have;

[tex] P = \frac {0.467*0.08206*432}{0.245} [/tex]

[tex] P = \frac {16.5551}{0.245} [/tex]

Pressure, P = 67.57 atm

Answer:

Physical and psychological dependence is high, and withdrawal symptoms include watery eyes, runny nose, loss of appetite, irritability, tremors, panic, abdominal cramps and diarrhea, nausea, chills, and sweating. Use of contaminated syringes/needles to inject drugs may result in serious blood borne infections such as HIV-AIDS and hepatitis.

Answer:

a. +0.40 V

Explanation:

Reduction of O2 in acid medium is +1.23 V. The reduction of O2 in basic medium will be calculated by subtracting equation of acidic medium from equation in base medium.

Kw^4 = [10^-14 ] ^ 4

solving we get -0.8274

Subtracting the value from oxygen reduction in acidic medium;

+ 1.23 - 0.8274 = +0.4026