Which of these changes is an example of a chemical change?

A. ice cream solidifying
B. a tree decomposing in a forest
C. a figure made from a block of modeling clay D. polishing a gemstone​

The pH of the 0.15 M [tex]CH_3COOH[/tex] solution is approximately 2.38. and around 2.9% of the [tex]CH_3COOH[/tex] molecules in the 0.15 M solution are deprotonated.

Acetic acid ([tex]CH_3COOH[/tex]) is a weak acid that only partially dissociates in water to form [tex]H^+[/tex] ions and [tex]CH_3COO^-[/tex] ions. To estimate the pH and fraction of [tex]CH_3COOH[/tex]molecules deprotonated in a 0.15 M [tex]CH_3COOH[/tex]solution, we can use the following equations and approximations:

The dissociation constant for acetic acid (Ka) is 1.8 x 10^-5.

The initial concentration of [tex]CH_3COOH[/tex] is equal to its concentration at equilibrium, since it only partially dissociates.

The concentration of [tex]H^+[/tex] ions is equal to the concentration of [tex]CH_3COO^-[/tex] ions at equilibrium, since the dissociation reaction involves a 1:1 ratio of [tex]H^+[/tex] ions to [tex]CH_3COO^-[/tex] ions.

Using these approximations, we can set up an equilibrium expression for the dissociation of [tex]CH_3COOH[/tex] :

[tex]Ka = [H^+][CH_3COO^-]/[CH_3COOH][/tex]

We also know that the initial concentration of [tex]CH_3COOH[/tex] is 0.15 M. Let x be the concentration of [tex]H^+[/tex] ions and [tex]CH_3COO^-[/tex] ions at equilibrium. Then:

[[tex]H^+[/tex]] = x

[[tex]CH_3COO^-[/tex]] = x

[[tex]CH_3COOH[/tex]] = 0.15 - x

Substituting these values into the equilibrium expression and solving for x, we get:

Ka = x^2 / (0.15 - x)

1.8 x 10^-5 = x^2 / (0.15 - x)

x = 0.0042 M

The pH can be calculated using the formula:

pH = -log[[tex]H^+[/tex]]

pH = -log(0.0042)

pH = 2.38

Therefore, the pH of the 0.15 M [tex]CH_3COOH[/tex] solution is approximately 2.38.

To estimate the fraction of [tex]CH_3COOH[/tex] molecules that are deprotonated, we can use the equation:

Fraction deprotonated = [tex][CH_3COO^-] / [CH_3COOH][/tex] x 100%

At equilibrium, the concentration of [tex]CH_3COO^-[/tex] ions is equal to the concentration of [tex]H^+[/tex] ions, which we calculated to be 0.0042 M. The concentration of [tex]CH_3COOH[/tex] at equilibrium is 0.15 - 0.0042 = 0.1458 M. Substituting these values into the equation, we get:

Fraction deprotonated = 0.0042 / 0.1458 x 100%

Fraction deprotonated = 2.9%

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The chemical elements involved are; hydrogen, fluorine, boron and lithium

There are two hydrogen atoms, five fluorine atoms, one boron atom and one lithium atom.

Chemical compounds are represented symbolically by chemical formulas, which reveal the types and amounts of atoms that make up the compound. It is a succinct approach to explain a substance's makeup.

The components of a compound are identified in a chemical formula by their corresponding chemical symbols, which are typically derived from their English or Latin names. The number of atoms of each element in a single compound molecule is indicated by the subscripts that follow each element.

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It is significant to remember that the order of a reaction affects how a reaction's half-life is calculated. It is commonly expressed in seconds and is represented by the sign "t 1/2." The amount which is left after 172.8 years is 0.8 g.

The time it takes for the concentration of a particular reactant to reach 50% of its initial concentration, or the time it takes for the reactant concentration to reach half of its initial value, is known as the half-life of a chemical reaction.

To calculate the remaining amount:

N₀ / N = 2ⁿ

n = time / t1/2

172.8 / 57.6 = 3

N = 2ⁿ / N₀

N = 2³ / 10 = 0.8 g

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The synthesis of N-methyl-4-(p-tolyldiazenyl)aniline can be accomplished in a few steps, as outlined below:

Step 1: Nitration of toluene

Step 2: Reduction of p-nitrotoluene

Step 3: Diazotization of p-toluidine

Step 4: Coupling with N-methylaniline

Toluene is first nitrated to form p-nitrotoluene. This can be done by treating toluene with a mixture of nitric acid and sulfuric acid under controlled conditions. The reaction can be represented as follows:

Toluene + HNO3 → p-nitrotoluene + H2O

The p-nitrotoluene is then reduced to form p-toluidine, using a reducing agent such as iron and hydrochloric acid. The reaction can be represented as follows:

p-nitrotoluene + 6HCl + Fe → p-toluidine + 3H2O + FeCl3

The p-toluidine is then diazotized using nitrous acid to form the diazonium salt. The reaction can be represented as follows:

p-toluidine + HNO2 → p-tolyldiazonium chloride + H2O

The diazonium salt is then coupled with N-methylaniline to form N-methyl-4-(p-tolyldiazenyl)aniline. The reaction can be represented as follows:

p-tolyldiazonium chloride + N-methylaniline → N-methyl-4-(p-tolyldiazenyl)aniline + HCl

Overall reaction:

Toluene + HNO3 → p-nitrotoluene + H2O

p-nitrotoluene + 6HCl + Fe → p-toluidine + 3H2O + FeCl3

p-toluidine + HNO2 → p-tolyldiazonium chloride + H2O

p-tolyldiazonium chloride + N-methylaniline → N-methyl-4-(p-tolyldiazenyl)aniline + HCl

It is important to note that these reactions require careful handling and should only be attempted by individuals with proper training and experience in organic chemistry.

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Here is the balanced chemical equation for the reaction involving [tex][Cu(OH_2)_6]^{2+}:[/tex]

[tex][Cu(OH_2)_6]^{2+} + 4Cl^- = [CuCl_4]^{2-} + 6H_2O[/tex]

In this reaction, [tex][Cu(OH_2)_6]^{2+}[/tex] is a complex ion of copper(II) that reacts with chloride ions to form the complex ion [tex][CuCl_4]^{2-}[/tex] and water molecules.

The balanced equation indicates that for every one mole of [tex][Cu(OH_2)_6]^{2+[/tex] that reacts, four moles of chloride ions are required and two moles of [tex][CuCl_4]^{2-[/tex] and six moles of water are produced.

A balanced chemical equation is a written representation of a chemical reaction that shows the same number of atoms of each element on both the reactant and product sides of the equation.

In other words, the law of conservation of mass is obeyed in a balanced chemical equation, which states that the total mass of the reactants must equal the total mass of the products.

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The heat capacity of a system is defined as the amount of heat required to raise the temperature through 1°C. It is denoted by c. It is an extensive property. The mass of steel bar is 47.93 g.

Here the amount of heat taken by the steel rod is equal to the amount of heat lost by water. The heat required to raise the temperature of the sample of mass 'm' having specific heat 'c' is:

Q = c (T - T₀) m

Cs (Ts - T0s) ms = -Cw (Tw - T0w) mw

ms = - Cw (Tw - T0w) mw / Cs (Ts - T0s)

Mass of water = 110 mL × 1.00 g / mL = 110.00 g

ms = -4.18 J / g°C × (21 .10 - 22.00) 110.00 g / 0.452 J / g°C (21.10 - 2.00) = 47.93 g

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1. Using your knowledge of the Brønsted-Lowry theory of acids and bases, complete the following acid-base reactions and indicate each conjugate acid-base pair.

i. OH + HPO₂ → H₂O + H₂PO₄²⁻

The conjugate acid-base pair is OH/H₂O, HPO₂²⁻/H₂PO₄²⁻

2) Identify the conjugate acid-base pairs in the following reactions. Write A, B, CA, and CB below the appropriate substance.

i. HCO₃⁻ + NH₃ → NH₄⁺ + CO₃²⁻

The conjugate acid-base pair is HCO₃⁻/CO₃²⁻, NH₃/NH₄⁺

ii. HCI + H₂O → H₃O⁺ + Cl⁻

The conjugate acid-base pair is H₂O/OH⁻, HCI/Cl⁻, H₃O⁺/H₂O, Cl⁻/HCI

iii. CH₃COOH + H₂O → H₃O⁺ + CH₃COO⁻

The conjugate acid-base pair is CH₃COOH/CH₃COO⁻, H₂O/OH⁻, H₃O⁺/H₂O

iv. HOCI + NH₃ → NH₄⁺ + ClO⁻

The conjugate acid-base pair is HOCI/ClO⁻, NH₃/NH₄⁺

3. Write the formula for conjugate bases formed by the following acids.

i. HPO₄²⁻ → PO₄³⁻

ii. H₂O → OH⁻

iii. CN⁻ → HCN

iv. HOOC-COO⁻ → HOOCCOOH

4) Write the formula for conjugate acids formed by each of the following bases.

i. H₃O⁺ → H₂O

ii. HCN → H₂CN⁺

iii. NH₃ → NH₄⁺

5. Classify each of the following pH values as acidic, basic, or neutral.

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The amount of heat absorbed by 400 grams of water from 20°C to 99°C is 132,214.4 J.

The amount of heat absorbed or released by a substance can be calculated using the following equation;

Q = mc∆T

Where;

According to this question, 400.0 grams of water is heated in a pot on the stove from 20ºC to 99°C. The amount of heat absorbed can be calculated as follows:

Q = 400 × 4.184 × {99 - 20}

Q = 132,214.4 J

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The velocity of the tomato when it hits the ground is approximately 13.49 meters per second.

The potential energy of the tomato is at the height of 10 meters. When the tomato hits the ground, most of the potential energy is E1 = 0.909*mgh.

By the conservation of energy principle, the kinetic energy [tex]E_1[/tex] is equal to the kinetic energy [tex]E_2[/tex] of the tomato just before it hits the ground.

The kinetic energy [tex]E_2[/tex] is given by[tex]1/2mv^2[/tex], where v is the velocity of the tomato just before it hits the ground. Equating [tex]E_1[/tex] and [tex]E_2[/tex] solving for v, we get:

[tex]v = \sqrt{(20.909gh)[/tex]

Substituting the values of [tex]g = 9.81 m/s^2[/tex]and h = 10 m, we get:

v = [tex]\sqrt{(20.9099.81*10)}[/tex] = 13.49 m/s

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--The complete Question is, Suppose a tomato is dropped from a height of 10 meters. If 90.9% of the work done on the tomato is converted to kinetic energy by the time it hits the ground, what is the velocity (in meters per second) of the tomato when it hits the ground? --

The quantity of protons, neutrons, and electrons that each element has makes it unique.

Each chemical element's atoms has the same number of protons and electrons, which is important because neutrons' quantities are variable.

Isotopes are atoms with the same number of protons but differing numbers of neutrons.

They differ in mass, which affects their physical characteristics even if they have nearly identical chemical properties. There are unstable isotopes that emit radiation as well as stable isotopes that do not. These are referred to as radioisotopes.

Thus, The quantity of protons, neutrons, and electrons that each element has makes it unique.

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27 grams of water are produced from the given amounts of hydrogen and oxygen.

To determine the amount of water produced from the reaction between hydrogen and oxygen, we need to compare the amounts of reactants (hydrogen and oxygen) to the stoichiometry of the balanced chemical equation.

The balanced equation is:

2H₂ + O₂ → 2H₂O

The molar mass of hydrogen (H₂) is 2 g/mol, and the molar mass of oxygen (O₂) is 32 g/mol.

Given:

Mass of hydrogen = 3 grams

Mass of oxygen = 24 grams

We can calculate the number of moles of each reactant by dividing their respective masses by their molar masses:

Number of moles of hydrogen = 3 grams / 2 g/mol = 1.5 moles

Number of moles of oxygen = 24 grams / 32 g/mol = 0.75 moles

According to the balanced equation, the ratio of hydrogen to water is 2:2, and the ratio of oxygen to water is 1:2. Therefore, the limiting reactant in this reaction is oxygen, as it is consumed in a smaller quantity compared to the stoichiometry of the reaction.

From the reaction, we can see that 1 mole of oxygen produces 2 moles of water. Thus, the number of moles of water produced is twice the number of moles of oxygen:

Number of moles of water = 2 * 0.75 moles = 1.5 moles

To determine the amount of water produced in grams, we multiply the number of moles by the molar mass of water (H₂O), which is approximately 18 g/mol:

Mass of water produced = 1.5 moles * 18 g/mol = 27 grams

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Answer is Answer

Explanation:

The three correct answers about the reactants they used for a successful reaction are:

The collision theory states that successful chemical reactions occur when reactant particles collide with each other with sufficient energy and proper orientation.

Based on the collision theory,  for a successful reaction to occur, the reactants must collide with each other with sufficient energy (activation energy) and in the correct orientation.

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Complete question:

For this question, choose THREE answers. A student adds two chemicals together in lab and observes a successful reaction. Which of the following can be assumed about the reactants they used?

They had the minimum activation energy.

They did not have the minimum activation energy.

They were not oriented in the correct direction.

They were oriented in the correct direction.

They did not successfully collide with each other.

They successfully collided with each other.

Answer:

Explanation:

The matching of each decimal number to the correct scientific notation is as follows:

3.07 x 10^-6 -> D) 3.07 x 10^-6

3.07 x 10^6 -> B) 3.07 x 10^6

3.07 x 10^-4 -> A) 3.07 x 10^-4

3.07 x 10^4 -> C) 3.07 x 10^4

So, the correct matching is:

D) 3.07 x 10^-6

B) 3.07 x 10^6

A) 3.07 x 10^-4

C) 3.07 x 10^4

The north pole of one magnet is near the South pole of the other magnet.

The ends of a magnet are called its poles. One end is called the north pole, the other is called the south pole. If you line up two magnets so that the south pole of one faces the north pole of the other, the magnets will pull toward each other.

The energy associated with the formation of 2.55 g of 4He by the fusion of 3H and 1H is approximately -[tex]2.57 * 10^{-12 }.[/tex] Joules

The balanced nuclear equation for the fusion of 3H and 1H to form 4He is shown below:

3H + 1H → 4He

We find that the difference in mass between the reactants and products is: (3 × 3.01605 u) + (1 × 1.00783 u) - (1 × 4.00260 u) = -0.01854 u

Einstein's energy equation is E = mc².

E = (-0.01854 u) × (1.66054 × 10^-27 kg/u) × (2.998 × 10^8 m/s)^2

E = [tex]-4.03 * 10^{-12}[/tex] J

The number of reactions  =  2.55 g / 4.00260 g/mol = 0.637 mol

The total energy is =  [tex]-4.03 * {10^-12} J[/tex]× 0.637 mol

total energy = [tex]2.57 * 10^{-12} J[/tex]

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The difference between q for the two-step process and q for the one-step process is 220.38 joules.

To solve this problem, we use the first law of thermodynamics, which states that change in internal energy (ΔU) of system will be equal to the heat (q) added or removed from the system, minus the work (w) done by or on the system;

[tex]Δ_{U}[/tex] = q - w

For an ideal gas, the internal energy depends only on the temperature, so [tex]Δ_{U}[/tex] is zero if the final temperature is the same for both processes. Therefore, we can set [tex]Δ_{U}[/tex] to zero and solve for the difference in heat (q) between the two processes;

q(two-step) - q(one-step) = w(two-step) - w(one-step)

The work done by or on the gas can be calculated using the equation;

w = -P[tex]Δ_{V}[/tex]

where P is the external pressure, and [tex]Δ_{U}[/tex] is the change in volume. The negative sign indicates that work is done on the gas when it is compressed ([tex]Δ_{U}[/tex] < 0), and work is done by the gas when it expands ([tex]Δ_{U}[/tex] > 0).

For the two-step process, we can calculate the work done in two stages;

w(two-step) = -2.00 atm × (4.40 L - 2.20 L) - 2.50 atm × (2.20 L - 1.76 L)

= -3.32 atm L - 0.605 atm L

= -3.925 atm L

For the one-step process, we can calculate the work done in one step;

w(one-step) = -2.50 atm × (4.40 L - 1.76 L)

= -6.10 atm L

Substituting these values into the equation for the difference in heat, we get;

q(two-step) - q(one-step) = -3.925 atm L - (-6.10 atm L)

= 2.175 atm L

To convert this to joules, we need to multiply by the conversion factor for atm L to joules;

1 atm L = 101.3 J

Therefore; q(two-step) - q(one-step) = 2.175 atm L × 101.3 J/atm L

= 220.38 J

Therefore, the difference in heat between the two processes is 220.38 joules.

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Answer:

0.625g/mL

Explanation:

D=mass (grams) / Volume (mL or cm^3)

m=125g
V=200mL

D= 125g/200mL= 0.625g/mL

Answer:

A

Explanation:

If Hydrogen is H₂  There will be two silver

and is Carbon is C There will only be one gray

and if Oxygen is O₃ There will be three red

Based on the information regarding the titration, as the pH of the solution decreases, phenolphthalein will change color to pink.

The best indicator to use for a titration where you start out with a basic solution of around 8.0 and you expect to keep adding an acid until the mixture has a pH of 3.0 is phenolphthalein.

Phenolphthalein is an indicator that changes color in the pH range of 8.3 to 10.0. In basic solutions, phenolphthalein is colorless. As the pH of the solution decreases, phenolphthalein will change color to pink. The color change will be observed at the equivalence point of the titration, which is the point at which the amount of acid added is equal to the amount of base present. At the equivalence point, the pH of the solution will be 7.0.

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The change in temperature (ΔT) when a 25 g block of aluminum absorbs 10,000 J of heat is approximately 44.32°C.

To calculate the change in temperature (T) that occurs when an aluminium block absorbs a certain quantity of heat, we must utilise the specific heat capacity of aluminium (c) and the equation:

Q = mcΔT

Where Q is the heat absorbed or released, m is the substance's mass, c is the substance's specific heat capacity, and T is the temperature change.

The specific heat capacity of aluminium is approximately 0.897 J/g°C.

Given that the aluminium block weighs 25 g and absorbs 10,000 J of heat, we can plug the following values into the equation:

(25 g) * (0.897 J/g°C) * T = 10,000 J

We can now solve for T:

T = 10,000 joules / [(25 g) * (0.897 J/g°C)]

ΔT ≈ 44.32°C

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a)The molarity of this solution is 0.07 M.

b)The hydronium ion concentration is 0.07 M, and the hydroxide ion concentration is approximately 1.43 x 10^(-13) M.

c)The pH ≈ 1.15 & pOH ≈ 12.85

d)This solution is an acid.

e)HNO₃ + NaOH → NaNO₃ + H₂O

f)HNO₃ is the acid.

NaOH is the base.

NaNO₃ is the conjugate acid of the base NaOH.

H₂O is the conjugate base of the acid HNO₃.

To find the molarity (M) of the solution, we need to calculate the number of moles of solute (hydrogen nitrate) and divide it by the volume of the solution in liters.

a.The molar mass of hydrogen nitrate (HNO3) is 63.01 g/mol.Moles of HNO3 = 3.31 g / 63.01 g/mol = 0.0526 mol

Volume of solution in liters = 750.0 mL / 1000 mL/L = 0.750 L

Molarity (M) = Moles of solute / Volume of solution in liters

M = 0.0526 mol / 0.750 L ≈ 0.070 M

b. Hydrogen nitrate (HNO3) dissociates in water to form hydronium ions (H3O+) and nitrate ions (NO3-). Since the compound is a strong acid, it fully dissociates. Thus, the concentration of hydronium ions and nitrate ions is the same as the molarity of the solution, which is 0.070 M.

c. The pH and pOH can be calculated using the formulas: pH = -log[H3O+] and pOH = -log[OH-]. Since the solution is acidic, [H3O+] = 0.070 M.

pH = -log(0.070) ≈ 1.155

pOH = 14 - pH ≈ 14 - 1.155 ≈ 12.845

d. This solution is an acid since it contains hydronium ions (H3O+), which are characteristic of acidic solutions.

e. The balanced chemical equation for the reaction between hydrogen nitrate (HNO3) and sodium hydroxide (NaOH) is:

HNO3 + NaOH -> NaNO3 + H2O

f. In this reaction, HNO3 acts as the acid (donates a proton, H+), NaOH acts as the base (accepts a proton, OH-), NaNO3 is the conjugate base of HNO3, and H2O is the conjugate acid of OH-.

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The balanced equation for the reaction between sulfur (S₈) and oxygen (O₂) to form sulfur trioxide (SO₃) is 2S₈ + 16O₂ → 16SO₃.

Balancing chemical equations involves the addition of stoichiometric coefficients to the reactants and products.

The balanced equation for the reaction between sulfur (S₈) and oxygen (O₂) to form sulfur trioxide (SO₃) is determined as;

2S₈ + 16O₂ → 16SO₃

From the reactants side we can see that sulfur is 16 and also 16 in the product side. The number of oxygen in the reactant side is 32 and also 32 in the product side.

Thus, the balanced equation for the reaction between sulfur (S₈) and oxygen (O₂) to form sulfur trioxide (SO₃) is 2S₈ + 16O₂ → 16SO₃.

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The reactions that result in the emission of light involve the ruthenium label and tripropylamine (TPA), two electrochemically active molecules.

Thus, The electrode surface inside the measurement cell is where the reactions take place.

The ruthenium label is oxidized at the electrode surface as an electrical potential is applied, and TPA is oxidized into a radical cation that spontaneously loses a proton.

When the resultant TPA radical interacts with oxidized ruthenium, the ruthenium label enters an excited state and emits a photon (620 nm) before decaying. The ruthenium label is renewed and ready to carry out numerous light-generating cycles as it goes back to its ground state.

Thus, The reactions that result in the emission of light involve the ruthenium label and tripropylamine (TPA), two electrochemically active molecules.

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The half-life of the radioactive isotope is 8 days.

Mass at 8 days = 8000 g

Number of half-lives in 4000 g = 8000 / 4000 = 2 half life

Time needed for 1000g to remain is 32 days.

The half life of a chemical reaction is the time required by the substance to reach half of its concentration. It is a characteristic property of the  unstable atomic nuclei and the way in which they decay.

For a given reaction the half life of a reactant is the time required for its concentration to reach a value that is the arithmetic mean of its initial and final value. For a reactant that is entirely consumed it is the time taken for the reactant concentration to fall to one half of its initial value.

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The gas would occupy approximately 3.00 L at 24.0 °C and 670 torr.

To solve this problem, we can use the combined gas law, which relates the pressure, volume, and temperature of a gas at different conditions. The combined gas law is expressed as:

(P1 × V1) / (T1) = (P2 × V2) / (T2)

where P1, V1, and T1 are the initial pressure, volume, and temperature, respectively, and P2, V2, and T2 are the final pressure, volume, and temperature, respectively.

Using the given values, we can plug them into the equation and solve for V2:

(P1 × V1) / (T1) = (P2 × V2) / (T2)

(934 torr × 4.76 L) / (279.25 K) = (670 torr × V2) / (297.15 K)

Simplifying and solving for V2, we get:

V2 = [(934 torr × 4.76 L) / (279.25 K)] × (297.15 K / 670 torr)

V2 ≈ 3.00 L

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