Is the reaction between hydrochloric acid and sodium hydroxide an exothermic or endothermic reaction? (1 mark)​

Answer:Sodium

Explanation:Sodium has 11 protons, 11 nuetrons, and 12 electrons

When exposed to lead at high levels, the brain and central nervous system are attacked, resulting in unconsciousness, convulsions, and even death.

Lead poisoning affects up to 800 million children worldwide, or close to one third of all children. Lead has a negative impact on a child's developing brain, leading to diminished IQ, behavioral difficulties, and learning issues that can lower potential earnings as an adult.

The Safe Drinking Water Act (SDWA) reduced the maximum permitted lead level, or "lead-free" content, to a weighted average of 0.25 percent measured throughout the wetted surfaces of pipes, pipe fittings, plumbing fixtures, and fixtures, and 0.2 percent for solder and flux.

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What are the toxic effects of lead? How can it affect the human body?

Answer:

Explanation:

Average Atomic Mass

In order to find the identity of the element, we must first find the average mass of all isotopes.

To do this, we multiply each mass by its percent abundance and add them together.

[tex](0.0435*49.9461)+(0.8379*51.9405)+(0.0950*52.9407)+(0.0236*53.9389)=51.9959[/tex]

51.9959 is the calculated average of the mass of each isotope.

Identity

Looking at a periodic table, this value for atomic mass most closely resembles the atomic mass of Chromium, which is 51.9961

Answer:

The balanced chemical equation for the reaction is:

CS2 + 3 Cl2 ➡️ CCl4 + S2Cl2

According to the equation, one mole of CS2 reacts with three moles of Cl2 to produce one mole of CCl4. The molar mass of CS2 is 76.14 g/mol, and the molar mass of CCl4 is 153.82 g/mol.

Theoretical yield of CCl4:

125 g CS2 × (1 mol CS2/76.14 g) × (1 mol CCl4/1 mol CS2) × (153.82 g CCl4/1 mol CCl4) = 318.3 g CCl4

This means that 318.3 g of CCl4 should have been produced according to the balanced equation.

Actual yield of CCl4 = 60.4 g

Percent yield = (actual yield / theoretical yield) × 100%

Percent yield = (60.4 g / 318.3 g) × 100%

Percent yield = 19%

Therefore, the percent yield of CCl4 is 19%.

Answer:

Activation Energy

Explanation:

Activation energy is the minimum amount of energy that reactant molecules must possess in order to undergo a chemical reaction. as it is necessary to break the bonds of between the molecules of the reactants.


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Answer:

22.24°C.

Explanation:

The change in temperature of the iron can be calculated using the formula: ΔT = Q / (m * c), where ΔT is the change in temperature, Q is the heat added, m is the mass of the substance and c is the specific heat capacity.

Substituting the given values into the formula: ΔT = 115 cal / (47.0 g * 0.11 cal/g⋅°C) ≈ 22.24°C

So, the change in temperature of the iron is 22.24°C.

The alcohol and water molecules sharing the same space leads to a more compact arrangement of the molecules in the combination, which is the best explanation for the observed drop in volume.

In this illustration, adding water to alcohol results in a final volume that is roughly 10% lower than the combined volumes of the two liquids. The "vanishing volume" results from variations in how the solvent molecules are packed in the mixture compared to the pure components.

Alcohol molecules slide into the spaces between the water molecules as it dissolves, reducing the volume.

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If 50cm³ of alcohol is mixed with 50cm³ of water. The volume of the mixture is 97cm³. What is the best explanation for this observation?

A. Water evaporates leading to decrease in volume of the mixture

B. Water and alcohol molecules react and form a compact solution

C. Alcohol being volatile evaporates and decreases the volume of the mixture

D. The alcohol and water molecules sharing the same space leads to the decrease in volume of the mixture

Restate original Claim here. This claim was supported by the claim because the evidence showed that acidic substances have a pH value less than 7 and cause the pH paper to turn a certain color.

What is pH?

pH is a measure of the acidity or basicity of a solution. It is defined as the negative logarithm of the concentration of hydrogen ions (H+) in a solution. pH values range from 0 to 14, where 0 is the most acidic, 7 is neutral, and 14 is the most basic. A change of one unit in pH represents a tenfold change in the concentration of hydrogen ions.

For example, from the evidence, fruit juices such as lemon juice have a pH value of around 2-3 and turn the pH paper a red color, which indicates acidity. Beverages such as coffee and soda also have a low pH value, around 4-5, and turn the pH paper a slightly red color. Cleaning products such as vinegar have a pH value of around 2-3 and turn the pH paper a red color as well.

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The value of the equilibrium constant, Kc is 0.33.

The correct option is A.

The balanced chemical equation for the oxidation of NO by O2 is:

2 NO (g) + O2 (g) → 2 NO2 (g)

From the stoichiometry of the equation, we see that the mole ratio of NO to O2 consumed is 2:1. Therefore, if 3 moles of O2 are present at equilibrium, then 1.5 moles of NO have been consumed:

1.5 moles NO = 15.0 moles NO (initial) - 3.0 moles NO2 - 3.0 moles O2

Using the law of mass action, we can express the equilibrium constant (Kc) for the reaction as:

Ke = ([NO2]^2 / [NO]^2 [O2])

We know that at equilibrium, [O2] = 3.0 moles / 1.0 L = 3.0 M. To calculate [NO2], we need to use the stoichiometry of the equation and the fact that 1.5 moles of NO are consumed at equilibrium:

2 mol NO → 2 mol NO2

1.5 mol NO → 1.5 mol NO2

Therefore, [NO2] = 1.5 mol NO2 / 1.0 L = 1.5 M. Substituting the values into the equilibrium constant expression, we get:

Ke = ([NO2]^2 / [NO]^2 [O2])

Ke = (1.5 M)^2 / (1.5 M)^2 (3.0 M)

Ke = 0.333

Therefore, the answer is (a) 0.33.

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The chemist's percent yield for this reaction is approximately 92.27%.

The percent yield for a chemical reaction is the ratio of the actual yield to the theoretical yield, expressed as a percentage. The theoretical yield is the amount of product that is expected to be obtained based on the stoichiometry of the reaction and the amounts of starting materials used. The actual yield is the amount of product that is actually obtained after the reaction is carried out and the product is purified.

To calculate the percent yield, we can use the formula:

Percent yield = (actual yield / theoretical yield) x 100%

In this case, the chemist calculated a theoretical yield of 216.4 g based on the amounts of starting materials used. However, she obtained an actual yield of 199.6 g after isolating and purifying the product.

So we can substitute these values into the formula and solve for the percent yield:

Percent yield = (199.6 g / 216.4 g) x 100%

Percent yield = 0.9227 x 100%

Percent yield = 92.27%

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Answer:

The base conjugate acid pair is NH3 and NH4+.

The molarity of the sodium hydroxide solution is 0.0911 M.

We must figure out how many molecules of potassium hydrogen phthalate there are.

moles of KHP = mass / molar mass = 0.600 g / 204.22 g/mol = 0.00294 mol

We know that 0.00294 moles of NaOH were used in the titration because one mole of KHP interacts with one mole of NaOH. This data can be used to determine the molarity of the NaOH solution:

molarity of NaOH = moles of NaOH / volume of NaOH used in liters

volume of NaOH = 32.21 mL = 0.03221 L

calculation of  the molarity of NaOH:

molarity of NaOH = 0.00294 mol / 0.03221 L = 0.0911 M

The molarity of the sodium hydroxide solution is 0.0911 M.

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Explanation:

To calculate the molarity of the vinegar solution, we first need to calculate the number of moles of acetic acid present in one liter of the solution.

Since the density of the solution is 1.01 g/mL, one liter of the solution will have a mass of 1.01 kg.

The mass of acetic acid in one liter of the solution can be calculated as follows:

mass of acetic acid = 5% × 1.01 kg = 0.0505 kg

The number of moles of acetic acid can be calculated using its molar mass:

moles of acetic acid = mass of acetic acid / molar mass of acetic acid

moles of acetic acid = 0.0505 kg / 60.052 g/mol

moles of acetic acid = 0.000841 mol

Therefore, the molarity of the vinegar solution is:

molarity = moles of acetic acid / volume of solution in liters

molarity = 0.000841 mol / 1 L

molarity = 0.000841 M

So, the molarity of a 5% vinegar solution is approximately 0.000841 M.

The reaction's per cent yield is  69.5%.

We must compare the actual yield of the reaction to the theoretical yield of the reaction to get the per cent yield of the reaction.

First, we need to calculate the amount of Pb reacted using the given mass of Pb:

mass of Pb = 451.4 g

The molar mass of Pb is 207.2 g/mol, so the number of moles of Pb reacted is:

moles of Pb = mass of Pb / molar mass of Pb

moles of Pb = 451.4 g / 207.2 g/mol

moles of Pb = 2.179 mol

The theoretical yield of PbO can be calculated using the molar mass of PbO:

mass of PbO = moles of PbO × molar mass of PbO

mass of PbO = 2.179 mol × 223.2 g/mol

mass of PbO = 486.6 g

Therefore, the theoretical yield of PbO is 486.6 g.

The per cent yield of the reaction is:

per cent yield = (actual yield / theoretical yield) × 100%

per cent yield = (338.4 g / 486.6 g) × 100%

percent yield = 69.5%

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One mole of glucose burns to produce several gases. [tex]6600kJ[/tex] of power. Another way to put it is that the burning of glucose releases  [tex]6600KJ/mol[/tex]  thermal energy.

A chemical reaction between two or more substances, typically containing oxygen, is called combustion. It results in the production of light and heat in the form of a flame.

The correct chemical formula for the burning of glucose

[tex]C6H12O6 + 6O2 \rightarrow  6CO2 + 6H2O[/tex]

We can determine the change in enthalpy for this reaction by using the values provided for the enthalpies of formation of the reactants and products:

Reactants:

[tex]C_6H_1_2O_6[/tex] : not given

[tex]O2: -498 kJ/mol \times 6 = -2988 kJ/mol[/tex]

Products:

[tex]CO_2[/tex]: not given

[tex]H2O -1598 kJ/mol \times 6 = -9588 kJ/mol[/tex]

[tex]\Delta H = (\epsilon products) - (\epsilon reactants)[/tex]

[tex]\Delta H = (-9588 kJ/mol + 0) - (0 + -2988 kJ/mol)[/tex]

[tex]\Delta H = -6600 kJ/mol[/tex]

Therefore, One mole of glucose burns to produce several gases. [tex]6600kJ[/tex] of power. Another way to put it is that the burning of glucose releases  [tex]6600KJ/mol[/tex]  thermal energy.

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The 37.2g of water must be heated from -15C to 135C using 23,447.04 joules of energy.

Heat transfer between two things is a result of their different masses. Heat transfer between two things is a result of their different densities. Heat transfer is a result of the temperature difference between two systems. Heat transmission between two objects is a result of pressure differences.

For calculating the heat:

Q = m × c × ΔT

Where:

Q = amount of heat (in joules)

m = mass of the substance (in grams)

c = specific heat capacity of the substance (in J/g·°C)

ΔT = change in temperature (in °C)

The specific heat capacity of water is approximately 4.184 J/g·°C.

Now, we have to calculate the change in temperature:

ΔT = final temperature - initial temperature

ΔT = 135⁰C - (-15⁰C)

ΔT = 150⁰C

Now, we can substitute the values,

Q = 37.2g × 4.184 J/g·°C × 150⁰C

Q = 23,447.04 J

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The order of the arrangement of the wavelengths from strongest to weakest is;

447 > 492 > 588 > 668

The wavelength is a fundamental property of a wave and is related to its frequency and speed through the equation:

wavelength = speed of light / frequency

where the speed of light is approximately 299,792,458 meters per second (m/s) and the frequency is measured in Hertz (Hz), which represents the number of cycles per second.

The wavelength is an important concept in many areas of physics, including optics, acoustics, and electromagnetic radiation.

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Answer:

time = 1.92 min

Explanation:

By knowing that

[tex]R_R = K_R [A]^{1} = \frac{[A]}{time}[/tex]  

Where: RR: rate of forward reaction, KR: rate constant, [A]: A concentration

in the previous equation, [A] is cancelled, then:

[tex]K_R = \frac{1}{time} \\ \\[/tex]


[tex]8.70\times10^{-3} = \frac{1}{time}[/tex]


Then, time = 114.94 seconds = 1.92 minutes


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Introduction: The formation of the solar system has been a subject of scientific inquiry for centuries. One of the most significant forces at play in the formation of the solar system is the law of universal gravitation.

This law states that every object in the universe attracts every other object with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them. In this virtual lab, we will investigate the law of universal gravitation by manipulating the size of the star and the positions of planets within Solar System X.

Hypothesis:

As the size of the star in Solar System X increases, the gravitational force experienced by the planets will increase, causing them to move closer to the star. Additionally, as the distance between the planets and the star decreases, the gravitational force experienced by the planets will also increase, causing them to move faster around the star.

Materials

Computer with internet connection

Virtual lab software

Solar System X simulation

Procedure:

Open the virtual lab software and access the Solar System X simulation.

Set the size of the star to the smallest setting and record the positions of the planets.

Increase the size of the star to the next setting and record the new positions of the planets.

Repeat step 3 until the largest size of the star is reached.

Analyze the data and record observations.

Results:

As the size of the star in Solar System X increased, the gravitational force experienced by the planets also increased. This caused the planets to move closer to the star and move faster around it. Additionally, as the distance between the planets and the star decreased, the gravitational force experienced by the planets also increased, causing them to move faster around the star. These observations support the hypothesis that the law of universal gravitation plays a significant role in the formation and movement of planets in a solar system.

Conclusion:

The law of universal gravitation is a fundamental force that plays a significant role in the formation and movement of planets in a solar system. This virtual lab demonstrated the effects of manipulating the size of the star and the positions of planets within Solar System X on the gravitational force experienced by the planets. The results of the experiment supported the hypothesis that increasing the size of the star and decreasing the distance between the planets and the star increased the gravitational force experienced by the planets, causing them to move faster and closer to the star. These observations provide valuable insight into the forces at play in the formation and movement of our own solar system and those found throughout the universe.

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10.0 mL of 0.115 M [tex]H_2SO_4[/tex] needs to be neutralised with 0.370 mL of a 0.310 M NaOH solution.

Calculate how much 0.310 M NaOH is required to neutralise 10.0 mL of 0.115 M [tex]H_2SO_4[/tex] in millilitres, we can apply the following formula:

Moles of [tex]H_2SO_4[/tex] = (Concentration of [tex]H_2SO_4[/tex])(Volume of [tex]H_2SO_4[/tex])

Moles of [tex]H_2SO_4[/tex] = (0.115 M)(10.0 mL) = 0.00115 moles

Since the reaction is 1 mole of [tex]H_2SO_4[/tex] to 2 moles of NaOH, we must have 0.00115 moles of NaOH to neutralize the [tex]H_2SO_4[/tex].

Moles of NaOH = (Concentration of NaOH)(Volume of NaOH)

0.00115 moles = (0.310 M)(Volume of NaOH)

Volume of NaOH =[tex]\frac{ 0.00115 moles}{0.310 M } = 0.370 mL[/tex]

Therefore, 0.370 mL of a 0.310 M NaOH solution are needed to neutralize 10.0 mL of 0.115 M [tex]H_2SO_4[/tex].

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The difference between the energy needed to break the bonds in the reactants and the energy released when new bonds are created in the products is what essentially determines the enthalpy change.

In general, a bond must be broken by a positive change in enthalpy, whereas a bond must be formed by a negative change in enthalpy. In other words, the process of breaking a bond is endothermic, whereas the process of forming a bond is exothermic.

The energy needed to break the links between the reactants less the energy released during the formation of new bonds in the products is the enthalpy of reaction.

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In terms of bonds breaking and forming, what's responsible for the enthalpy change?

the normality of the solution that results when 4.0g of Al(NO₃)₃ (MW = 213.0) is dissolved in enough water to give 250mL of solution the molarity of the solution is 0.0751 M.

To calculate the normality and molarity of the solution, we need to know the number of moles of Al(NO₃)₃ in the solution.

The number of moles can be calculated as:

moles = mass / molar mass

where mass is the mass of Al(NO₃)₃ and molar mass is the molecular weight of Al(NO₃)₃

Substituting the given values, we get:

moles = 4.0 g / 213.0 g/mol = 0.01878 mol

The volume of the solution is given as 250 mL, which is equivalent to 0.25 L.

The normality of the solution is defined as the number of equivalents of solute per liter of solution. For Al(NO₃)₃, each mole of the compound produces 3 moles of ions, so the number of equivalents of Al(NO₃)₃ is:

equivalents = moles x 3

Substituting the value of moles, we get:

equivalents = 0.01878 mol x 3 = 0.05634 eq

The normality can now be calculated as:

normality = equivalents / volume

Substituting the given values, we get:

normality = 0.05634 eq / 0.25 L = 0.225 N

Therefore, the normality of the solution is 0.225 N.

The molarity of the solution is defined as the number of moles of solute per liter of solution. The number of moles of Al(NO₃)₃ in 250 mL of solution is the same as the number of moles in 1 L of solution, which is 0.01878 mol. Therefore, the molarity of the solution is:

molarity = moles / volume

Substituting the given values, we get:

molarity = 0.01878 mol / 0.25 L = 0.0751 M

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Gay-Lussac's Law-

[tex] \:\:\:\:\:\:\star\longrightarrow \underline{\sf \boxed{\sf \dfrac{P_1}{T_1}=\dfrac{P_2}{T_2}}}[/tex]

[tex] \:\:\:\:\:\:\star\longrightarrow \sf \underline{P_2=\dfrac{P_1 \:T_2}{T_1}}[/tex]

Where-

As per question, we are given -

Now that we are given all the required values, so we can put them into the formula and solve for P₂:-

[tex] \:\:\:\:\:\:\:\:\:\:\:\:\longrightarrow \sf P_2=\dfrac{P_1 \:T_2}{T_1}\\[/tex]

[tex] \:\:\:\:\:\:\:\:\:\:\:\:\longrightarrow \sf P_2=\dfrac{6.8\times 211}{539}\\[/tex]

[tex]\:\:\:\:\:\: \:\:\:\:\:\:\longrightarrow \sf P_2 = \dfrac{1434.8}{539}\\[/tex]

[tex] \:\:\:\:\:\:\:\:\:\:\:\:\longrightarrow \sf P_2 = 2.661966.........\\[/tex]

[tex]\:\:\:\:\:\: \:\:\:\:\:\:\longrightarrow \sf\underline{ P_2 = 2.7 \:KPa}\\[/tex]

Therefore, If the temperature decreases to 211K, then the new pressure will become 2.7 KPa.

The volume of oxygen produced in the decomposition of 5 moles of KCIO3 at STP is 168 L. The balanced chemical equation for the decomposition of KCIO3 is:

2KClO3(s) → 2KCl(s) + 3O2(g)

From the equation, we can see that for every 2 moles of KCIO3, 3 moles of O2 are produced. Therefore, for 5 moles of KCIO3, the number of moles of O2 produced can be calculated as follows:

5 moles KCIO3 x (3 moles O2/2 moles KCIO3) = 7.5 moles O2

Since the conditions are given as STP (standard temperature and pressure), we can use the molar volume of a gas at STP (22.4 L/mol) to calculate the volume of O2 produced:

7.5 moles O2 x 22.4 L/mol = 168 L O2

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It is the least reactive of the three elements listed.  The correct order of elements from most to least reactive is:

sodium, carbon, krypton.

Sodium is a highly reactive metal and readily forms compounds with many other elements. It reacts vigorously with water and air, which is why it is stored in oil to prevent contact with moisture or oxygen.

Carbon is less reactive than sodium but can still undergo reactions, such as combustion or oxidation. Krypton, on the other hand, is a noble gas and is chemically inert, meaning it does not react with other elements under normal conditions. Therefore, it is the least reactive of the three elements listed.

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Explanation:

The process is called bleaching. Chlorine gas (Cl2) reacts with water to form hypochlorous acid (HOCl) and hydrochloric acid (HCl). Hypochlorous acid acts as a powerful oxidizing agent and removes electrons from the red litmus paper, causing it to turn white.

Answer:

0.0924 mol Al₂O₃ = 9.42 g

0.0165 mol Be₃Al₂(SiO₃)₆ = 8.87 g

0.0380 mol MgAl₂(SiO₄)₃ = 13.5 g

Explanation:

mass = number of moles * molar mass

(PART A) The molar mass of Al₂O₃ is 101.96 g/mol. To find the mass in grams of Al₂O₃ that are in 0.0924 moles:

0.0924 mol * 101.96 g/mol = 9.42 g

(PART B) The molar mass of Be₃Al₂(SiO₃)₆ is 537.51 g/mol. To calculate the mass in grams of 0.0165 moles of Be₃Al₂(SiO₃)₆:

0.0165 mol * 537.51 g/mol = 8.87 g

(PART C) The molar mass of MgAl₂(SiO₄)₃ is 354.52 g/mol. To calculate the mass in grams of 0.0380 moles of MgAl₂(SiO₄)₃:

0.0380 mol * 354.52 g/mol = 13.5 g

The mass of ruby in grams is 9.43 g.
The mass of emerald in grams is 8.87 g.
The mass of garnet in grams is 16.56 g.

To calculate the mass of a compound in grams, we need to know the molar mass of the compound, which is the sum of the atomic masses of all the atoms in the formula. Once we know the molar mass, we can use the formula:

mass in grams = number of moles x molar mass

where the number of moles is given and the molar mass is calculated from the formula. In each case, we plug in the numbers and perform the calculation to obtain the mass in grams.

PART A: molar mass of Al₂O₃ is 101.96 g/mol (2 x 26.98 g/mol for Al and 3 x 16.00 g/mol for O).

As a result, the ruby mass in grammes is:

0.0924 moles x 101.96 g/mol = 9.43 g

PART B: The molar mass of Be₃Al₂(SiO₃)₆ is 537.54 g/mol (3 x 9.01 g/mol for Be, 2 x 26.98 g/mol for Al, 6 x 28.09 g/mol for SiO₃).

Therefore, The mass of an emerald in gram is :

0.0165 moles x 537.54 g/mol = 8.87 g

PART C: The molar mass of MgAl₂(SiO₄)₃ is 435.52 g/mol (1 x 24.31 g/mol for Mg, 2 x 26.98 g/mol for Al, 3 x 60.08 g/mol for SiO₄).

Therefore, the garnet mass in grams is :

0.0380 moles x 435.52 g/mol = 16.56 g

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1.02 mol of carbon monoxide gas will occupy a volume of approximately 22.8 liters at STP.

At STP (standard temperature and pressure), the temperature is 273.15 K (0°C) and the pressure is 1 atmosphere (atm). The molar volume of a gas at STP is 22.4 L/mol.

Using the ideal gas law, we can calculate the volume of 1.02 mol of carbon monoxide gas at STP: PV = nRT

where:

P = pressure = 1 atm

V = volume (unknown)

n = moles = 1.02 mol

R = gas constant = 0.0821 L·atm/(mol·K)

T = temperature = 273.15 K

V = (nRT)/P

putting the values,

V = (1.02 mol)(0.0821 L·atm/(mol·K))(273.15 K) / (1 atm)

V = 22.4 L/mol

V = 22.8 L

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