A mass of 100 g of NaNO3 is dissolved in 100 g of water. At what temperature should solid crystals form?

Answer:

To calculate the frequency of a photon with energy of 5.27 × 10⁻¹⁹ J, we can use the equation E = hf, where E is the energy of the photon, h is Planck's constant (6.626 × 10⁻³⁴ J • s), and f is the frequency of the photon. Solving for f, we get:

f = E/h = (5.27 × 10⁻¹⁹ J)/(6.626 × 10⁻³⁴ J • s) = 7.95 × 10¹⁴ Hz

Therefore, the frequency of the photon is 7.95 × 10¹⁴ Hz.

Explanation:

The structural formula for 6-Ethyl-4,7-dimethyl-non-1-ene can be represented as follows:

[tex]CH_{3} CH_{3} CH_{3}[/tex]

| | |

[tex]CH_{2} CH_{2} CH_{2} CH_{2} CH_{2} CH_{2} CH_{2} CH_{2} CH_{2} CH_{3}[/tex]

| | | | | | |

[tex]CH CH CH CH CH CH CH[/tex]

|

[tex]CH_{2}[/tex]

In this structural formula, the main chain contains nine carbon atoms (non-1-ene) with a double bond (ene) located at the first carbon atom. Starting from the first carbon atom, we have:

At the sixth carbon atom, there is an ethyl group (CH3CH2-), which means an ethyl group is attached to it.

At the fourth and seventh carbon atoms, there are methyl groups (CH3-), which means a methyl group is attached to each of them.

The remaining carbon atoms in the main chain have a single hydrogen atom (H) attached to them.

This structural formula represents the arrangement of atoms and bonds in the molecule and provides information about the connectivity of the atoms in the compound. It helps visualize the spatial arrangement of the atoms and functional groups, enabling a better understanding of the compound's chemical properties and reactions.

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The ice is used to regulate and control the temperature during the dehydration of [tex]hydrated copper(II) sulfate[/tex], ensuring a safer and more controlled process.

When [tex]hydrated copper(II) sulfate[/tex] [tex](CuSO_ {4} .H_{4} O)[/tex] is heated, the purpose of the ice is to provide a cooling effect during the process. The hydrated copper(II) sulfate contains water molecules (H2O) that are chemically bonded to the copper sulfate compound. The formula [tex]CuSO_{4} .H_{2} O[/tex] indicates that there are x moles of water molecules per mole of copper(II) sulfate.

As the [tex]hydrated copper(II) sulfate[/tex] is heated, the heat energy causes the water molecules to undergo a physical change and turn into steam. This process is known as dehydration. The water molecules break their chemical bonds with the copper sulfate compound and are released in the form of steam.

The presence of ice during the heating process helps maintain a lower temperature in the reaction vessel. The ice absorbs the heat energy from the surroundings, allowing for a controlled and gradual increase in temperature. This controlled heating prevents sudden temperature changes and potential hazards, such as splattering or overheating.

In summary, the ice is used to regulate and control the temperature during the dehydration of [tex]hydrated copper(II) sulfate[/tex], ensuring a safer and more controlled process.

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The molar mass of ZnI2 is approximately 319.18 grams per mole.

To determine the molar mass of ZnI2 (zinc iodide), we need to know the atomic masses of zinc (Zn) and iodine (I) and their respective subscripts in the chemical formula.

The atomic mass of zinc (Zn) is approximately 65.38 grams per mole (g/mol), as found on the periodic table. The atomic mass of iodine (I) is approximately 126.90 g/mol.

Since the chemical formula of zinc iodide is ZnI2, it means there are two iodine atoms for every one zinc atom. Therefore, we multiply the atomic mass of iodine by 2.

Molar mass of ZnI2 = (atomic mass of Zn) + 2 × (atomic mass of I)

                 = 65.38 g/mol + 2 × 126.90 g/mol

                 = 65.38 g/mol + 253.80 g/mol

                 = 319.18 g/mol

Hence, the molar mass of ZnI2 is approximately 319.18 grams per mole.

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Atoms of different substances differ by weight. Option D

A) Atoms are real even though they're invisible: Dalton proposed that atoms are fundamental, indivisible particles that make up all matter. While atoms themselves cannot be observed directly, their existence and behavior can be inferred through their effects on matter.

B) The atom could be divided into smaller parts: Initially, Dalton believed that atoms were indivisible and the ultimate building blocks of matter. However, subsequent scientific discoveries, such as the discovery of subatomic particles like protons, neutrons, and electrons, revealed that atoms could be further divided into smaller components.

C) All atoms of a single substance are identical: Dalton postulated that atoms of the same element are identical in size, mass, and chemical properties. According to his atomic theory, different elements are composed of unique atoms, and atoms of the same element are identical to one another.

D) Atoms of different substances differ by weight: Dalton recognized that atoms have different masses and proposed that the differences in atomic weight account for the distinct properties of different elements. He formulated the law of multiple proportions, which states that elements combine in fixed ratios of masses to form compounds.

Option D

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Answer:105.99 g/mol

Explanation:

Sodium carbonate is the inorganic compound with the formula Na₂CO₃ and its various hydrates. All forms are white, odourless, water-soluble salts that yield alkaline solutions in water.

Answer:

Percent composition tells you the relative amounts of each element in a molecule by mass. It can be used to determine the empirical formula of a compound, as well as to compare the composition of different molecules.

For example, the percent composition of water (H2O) is 11.19% hydrogen and 88.81% oxygen by mass. This tells us that there are two hydrogen atoms for every one oxygen atom in the molecule.

Explanation:

Brainliest Plsss

The latent heat of fusion measures " The energy required to melt a substance" option (A).

The latent heat of fusion refers to the amount of energy required to change a substance from a solid state to a liquid state at its melting point while keeping the temperature constant. It is a specific type of latent heat that measures the energy needed for the phase transition of a substance.

When a substance is in a solid state, its particles are tightly packed and have a regular arrangement. As heat is added to the substance, its temperature gradually rises until it reaches the melting point. At this point, further addition of heat does not increase the temperature but instead causes the substance to undergo a phase change and transform into a liquid state. The energy absorbed during this process is known as the latent heat of fusion.

This energy is used to overcome the attractive forces between the particles in the solid and allow them to break free and move more freely in the liquid state. The latent heat of fusion is crucial in various practical applications, such as melting ice, changing solid metals into liquid form for casting, or utilizing phase change materials for thermal energy storage.

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Answer:

HI is the formula of hydroiodic acid

Explanation:

hope it helps you

Electrolysis of nitric acid produces hydrogen gas at the cathode and nitrogen dioxide, oxygen gas, and hydrogen ions at the anode.

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Taking 1500 mg of vitamin C daily amounts to approximately 1.2045 pounds per year.

Dr. Linus Pauling suggested that taking 1500 mg of vitamin C daily could result in milder and fewer colds. To determine the weight in pounds per year, we'll first convert milligrams to pounds and then multiply by the number of days in a year.

To convert milligrams to pounds, we need to know that there are 453,592.37 milligrams in a pound. Therefore, 1500 mg is equal to 0.0033 pounds (1500 mg / 453,592.37 mg/lb).

Now, to calculate the weight in pounds per year, we'll multiply 0.0033 pounds by the number of days in a year (365).

Weight in pounds per year = 0.0033 pounds/day * 365 days/year = 1.2045 pounds/year.

Therefore, taking 1500 mg of vitamin C daily amounts to approximately 1.2045 pounds per year.

It's important to note that while this calculation provides the weight equivalent, the effectiveness and recommended dosage of vitamin C for preventing colds should be discussed with a healthcare professional, as individual needs may vary.

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A precipitation reaction is a chemical reaction in which a solid forms when two aqueous solutions are mixed. The correct answer is option B: [tex]K_2CO_3 + PbCl_2 \rightarrow 2KCl + PbCO_3.[/tex]

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To make advances in the way skin cancer patients are treated, a scientist should first conduct thorough research and gather relevant information.

Review existing literature: The scientist should study the current scientific literature on skin cancer treatment, including the latest research, clinical trials, and treatment options. This will provide a foundation of knowledge and help identify gaps or areas that need improvement.

Understand the current challenges: It is important for the scientist to have a comprehensive understanding of the challenges faced by skin cancer patients and healthcare providers in existing treatment methods. This can involve analyzing the limitations of current therapies, side effects, recurrence rates, and patient outcomes.

Identify unmet needs: Through research and engagement with dermatologists, oncologists, and patients, the scientist should identify specific unmet needs in skin cancer treatment. This can include areas such as early detection methods, personalized therapies, targeted drug delivery, or improving the effectiveness of existing treatments.

Collaborate with multidisciplinary teams: Skin cancer treatment often requires collaboration between various specialists, including dermatologists, oncologists, surgeons, and researchers. The scientist should establish collaborations with experts from different disciplines to gain diverse perspectives and insights.

Conduct preclinical and clinical research: Once the specific objectives are identified, the scientist should design and conduct preclinical studies to explore potential treatment approaches. This can involve laboratory experiments, animal models, and in vitro studies.

Evaluate safety and efficacy: During clinical trials, the scientist should rigorously evaluate the safety and efficacy of the new treatment approach. This includes monitoring patient responses, side effects, and overall outcomes.

Analyze and disseminate results: The scientist should carefully analyze the data collected during the research and communicate the findings through scientific publications, conferences, and collaborations.

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The wavelength of 1212.7 Å corresponds to an electronic transition from n=1 to n=2, while the wavelength of 6562.8 Å does not have enough information to determine the value of n.

In atomic spectra, the wavelength of spectral lines corresponds to specific electronic transitions within an atom. Each line is associated with a particular energy level transition, which is characterized by the principal quantum number (n) of the electronic orbitals involved.

Let's analyze the given wavelengths:

Wavelength of 1212.7 Å: This wavelength corresponds to a transition involving the principal quantum numbers n and n-2. We need to find the values of n for this transition.

We know that the Balmer series in the hydrogen atom is defined by transitions from higher energy levels to the n=2 level. Therefore, the wavelength of 1212.7 Å corresponds to an electronic transition within the Balmer series. From the Balmer series formula,

1/λ = R_H * [tex](1/2^2 - 1/n^2[/tex]), where R_H is the Rydberg constant for hydrogen, we can solve for n. Rearranging the formula, we get:

1/λ = R_H * (1/4 - 1/[tex]n^2[/tex])

1/λ = R_H/n^2 - R_H/4

1/λ + R_H/4 = R_H[tex]/n^2[/tex]

1/λ + 109677 cm^-1 = 109677 cm^-1/n^2

Substituting the value of the wavelength (1212.7 Å = 121270 nm = 12127000 Å) into the equation, we can solve for n:

1/12127000 + 109677 cm^-1 = 109677 cm^-1/n^2

[tex]n^2[/tex] = 109677 cm^-1 / (1/12127000 + 109677 cm^-1)

[tex]n^2[/tex]≈ 109677 cm^-1 / 109678 cm^-1

n ≈ sqrt(1) ≈ 1

Therefore, the electronic transition corresponding to the wavelength of 1212.7 Å is from n=1 to n=2.

Wavelength of 6562.8 Å: This wavelength corresponds to a transition involving the principal quantum numbers n and n-2. To determine the value of n for this transition, we can use a similar approach as before. However, since the wavelength is not specified further, we cannot determine the exact series or atom.

Different atoms or series can have transitions that produce the same wavelength. Without additional information, we cannot pinpoint the specific value of n for this wavelength.

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The original pressure[P₁] is approximately 0.0848 atm

We can use the combined gas law equation, which relates the initial and final conditions of a gas sample. The combined gas law equation is as follows:

(P₁ × V₁) / (T₁) = (P₂ × V₂) / (T₂)

Given:

V₁ = 33 liters

T₁ = 24 °C = 24 + 273.15 = 297.15 K (converted to Kelvin)

V₂ = 41,000 milliliters = 41 liters (converted to liters)

T₂ = 13 °C = 13 + 273.15 = 286.15 K (converted to Kelvin)

P₂ = 2.7 atm

We need to find P₁, the original pressure.

Plugging in the values into the combined gas law equation:

(P₁ × 33) / (297.15) = (2.7 × 41) / (286.15)

Simplifying the equation:

33P₁ = (2.7 × 41 × 297.15) / (286.15)

33P₁ ≈ 2.804

Dividing both sides by 33:

P₁ ≈ 2.804 / 33

P₁ ≈ 0.0848 atm

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For the solution with a pH of 7.9:

pH = 7.9

pOH = 14 - pH = 14 - 7.9 = 6.1

[H+] = 10^(-pH) = 10^(-7.9) (in mol/L)

[OH-] = 10^(-pOH) = 10^(-6.1) (in mol/L)

The pH of a solution is a measure of its acidity, while pOH is a measure of its alkalinity. The pH and pOH values are related through the equation pH + pOH = 14.

For the solution with a pH of 4.5:

pH = 4.5

pOH = 14 - pH = 14 - 4.5 = 9.5

[H+] = 10^(-pH) = 10^(-4.5) (in mol/L)

[OH-] = 10^(-pOH) = 10^(-9.5) (in mol/L)

For the solution with a pH of 7.9:

pH = 7.9

pOH = 14 - pH = 14 - 7.9 = 6.1

[H+] = 10^(-pH) = 10^(-7.9) (in mol/L)

[OH-] = 10^(-pOH) = 10^(-6.1) (in mol/L)

Note: The [H+] and [OH-] concentrations can also be calculated using the equation [H+][OH-] = 1 x 10^(-14) at 25°C.

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C. 2, hydrogen atoms could bong with oxygen in this illustration of an oxygen atom.

In the given illustration of an oxygen atom, there are two unpaired electrons in the outermost electron shell. Each oxygen atom can form a covalent bond by sharing one electron with another atom. In the case of oxygen, it has a valence of 2, which means it can form up to two covalent bonds. Each hydrogen atom has one electron, and it requires one additional electron to complete its outermost electron shell.

Therefore, in the given illustration, the oxygen atom can form two covalent bonds with hydrogen atoms. This is represented by the formula H2O, where one oxygen atom is bonded to two hydrogen atoms.

Hence, the correct answer is C. 2. Two hydrogen atoms can bond with one oxygen atom to form a stable molecule of water. The sharing of electrons in covalent bonds allows atoms to achieve a more stable electron configuration and form compounds with different properties.

The question was incomplete. find the full content below:

How many hydrogen atoms could bong with oxygen in this illustration of an oxygen atom?

A. 0

B. 1

C. 2

D. 6.

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Compared to the freezing point and boiling point of water at 1 atmosphere, a solution of salt and water at 1 atmosphere has a option b. lower freezing point and a higher boiling point.

When a solute, such as salt, is added to water, it affects the properties of the solution, including its freezing and boiling points. Adding salt to water lowers the freezing point and raises the boiling point compared to pure water at the same pressure.

Lower Freezing Point: The presence of salt disrupts the formation of ice crystals, making it more difficult for the water molecules to arrange into a solid structure. This results in a lower freezing point for the saltwater solution compared to pure water.

Higher Boiling Point: The dissolved salt particles increase the boiling point of the solution. It requires more energy to break the intermolecular forces between the water and salt molecules, resulting in a higher boiling point for the saltwater solution compared to pure water.

Therefore, option B is correct: a solution of salt and water at 1 atmosphere has a lower freezing point and a higher boiling point compared to pure water.

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The correct answer is :

Compared to the freezing point and boiling point of water at 1 atmosphere, a solution of salt and water at 1 atmosphere has a

A. lower freezing point and a lower boiling point.

B. lower freezing point and a higher boiling point.

C. higher freezing point and a lower boiling point.

D. higher freezing point and a higher boiling point.

The standard free energy change at 25℃ is -2.48 × 10⁴ J/mol.

The equation linking Gibbs free energy change and equilibrium constant is given by the following equation:

ΔG° = -RT ln K(where, ΔG° is the standard free energy change, R is the gas constant, T is the temperature in Kelvin and K is the equilibrium constant)

Substituting the given values:Equilibrium constant, K = 1.3 × 10⁴

Standard temperature, T = 25℃ = 298K

Substituting the values in the equation of Gibbs free energy change:

ΔG° = -RT ln K=-8.31 J K⁻¹ mol⁻¹ × 298 K × ln 1.3 × 10⁴

      = -8.31 J K⁻¹ mol⁻¹ × 298 K × 9.480

     = -2.48 × 10⁴ J/mol (Approx)

Therefore, the standard free energy change at 25℃ is -2.48 × 10⁴ J/mol.

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The pressure (P) of the manager's pop machine is 0.38 psi or 0.026 atm.

Given the following values:

Temperature (T) = 12 °C

Volume (V) = 450 mL = 0.45 L

Pressure (P) = UnknownTemperature (T) = 5 °C

Volume (V) = 355 mL = 0.355 L

Pressure (P) = 7 psi = 0.48 atm

To find the pressure (P) of the manager's pop machine in both psi and atm, we can use the Ideal Gas Law, which is given by: PV = nRT

Where:

P = Pressure  V = Volume  T = Temperature  n = Number of moles  R = Universal gas constant

Let's first convert the volume and temperature to SI units.

Volume (V) = 0.45 L  

Temperature (T) = 12 + 273 = 285 K

For the first condition, we have: P1V1/T1 = nR/P1V1/T1 = P2V2/T2 (At constant temperature and volume)

P2 = P1(V2/V1)

For the second condition, we have: P1V1/T1 = P2V2/T2P2 = (P1V1T2)/(V2T1)

Now, let's plug in the values.P1 = ?V1 = 0.45 LT1 = 285 KP2 = 7 psi = 0.48 atmV2 = 0.355 LT2 = 278 K (5°C + 273)

First, we'll find the pressure (P) in psi. P2 = P1(V2/V1)0.48 = P1(0.355/0.45)P1 = 0.38 psi

To convert psi to atm, we use the following conversion factor: 1 atm = 14.7 psi0.38 psi x (1 atm/14.7 psi) = 0.026 atm.

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Answer: 100 ohms.

Explanation:

The circuit is composed of two parallel branches (upper and lower), with one resistor in the upper branch (150) and two resistors in the lower branch (250 and 50).

The lower branch resistors are in series, so the lower branch's resistance is:

250 + 50 = 300.

Now, the upper branch (150) and total lower branch (300) are in parallel, so:

[tex]\frac{1}{R} = \frac{1}{150} + \frac{1}{300}[/tex]

That is,

[tex]\frac{1}{R} = \frac{3}{300} = \frac{1}{100}[/tex],

Solving for R, we find R = 100.

The equivalent resistance of this circuit is 100 ohms.

There are approximately 1.203 × 10^24 atoms of oxygen in 60 grams of acetic acid.

To determine the number of atoms of oxygen in 60 grams of acetic acid (CH3COOH), we need to consider the molar mass and the molecular formula of acetic acid.

The molar mass of acetic acid can be calculated by summing the atomic masses of each element in its molecular formula. The atomic masses of carbon (C), hydrogen (H), and oxygen (O) are approximately 12.01 g/mol, 1.01 g/mol, and 16.00 g/mol, respectively.

Molar mass of CH3COOH = (1 × 12.01 g/mol) + (4 × 1.01 g/mol) + (2 × 16.00 g/mol) + 1.01 g/mol

= 60.05 g/mol

Now, we can calculate the number of moles of acetic acid in 60 grams using the molar mass:

Number of moles = Mass / Molar mass

= 60 g / 60.05 g/mol

≈ 0.999 moles

From the molecular formula of acetic acid, we can see that there are two atoms of oxygen in each molecule.

Therefore, the number of atoms of oxygen in 60 grams of acetic acid can be calculated by multiplying the number of moles by the Avogadro's number, which represents the number of particles (atoms, molecules, or ions) in one mole of a substance. Avogadro's number is approximately 6.022 × 10^23 particles/mol.

Number of atoms of oxygen = Number of moles × Avogadro's number × Number of oxygen atoms in one molecule

= 0.999 moles × 6.022 × 10^23 particles/mol × 2

≈ 1.203 × 10^24 atoms

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Answer:

x*10ⁿ (units)

Explanation:

Scientific notation never has leading or trailing zeros.

0.0064 would be expressed as 6.4*10³

6400 would be expressed as 6.4*10³

multiplying by 10 to an exponent just adds or subtracts zeros, so count how many zeros have to be added or subtracted, and multiply by 10ⁿ, where n is how far from the decimal point.

Batteries have potential energy in their chemical energy stores.

The one word that completes the sentence is "chemical." Batteries store potential energy in the form of chemical energy. This means that the energy is stored within the chemical components of the battery.
Here's a step-by-step explanation:
1. Batteries are devices that convert chemical energy into electrical energy.
2. Chemical energy is the energy stored within the chemical bonds of a substance.
3. In the case of batteries, this chemical energy is stored in the chemical components of the battery, such as the electrolyte and the electrodes.
4. When a battery is connected to a circuit, a chemical reaction takes place within the battery, causing the stored chemical energy to be converted into electrical energy.
5. This electrical energy can then be used to power electronic devices or perform other tasks.
To summarize, batteries store potential energy in their chemical energy stores. This potential energy is converted into electrical energy when the battery is used.

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Raising the temperature enhances the reaction rate by increasing the kinetic energy of the enzyme and substrate molecules.

An enzyme, a biological catalyst, plays a crucial role in accelerating the pace of chemical reactions. Enzymes, predominantly composed of proteins, possess remarkable specificity in the reactions they catalyze.

This specificity arises from the structural configuration of the enzyme, which complements the shape of the substrate—the specific molecule subjected to enzymatic catalysis.

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The mass of wire that reacted to silver nitrate solution is 5.15 grams.

To calculate the mass of the wire that reacted with silver nitrate solution, we need to consider the stoichiometry of the reaction. The reaction between copper and silver nitrate can be represented by the following equation:

Cu + 2AgNO3 → Cu(NO3)2 + 2Ag

According to the equation, one mole of copper reacts with two moles of silver nitrate to form one mole of copper(II) nitrate and two moles of silver.

Given that the mass of copper before the reaction is 1.52 grams, we can calculate the molar mass of copper using its atomic mass, which is 63.55 grams/mol.

1.52 g of copper is equal to 1.52 g / 63.55 g/mol = 0.0239 moles of copper.

Since the reaction stoichiometry is 1:2 between copper and silver, the moles of copper reacting would be equal to half of the moles of silver formed.

Therefore, the moles of silver formed would be 0.0239 moles x 2 = 0.0478 moles.

To find the mass of silver, we multiply the moles of silver by its molar mass, which is 107.87 grams/mol:

Mass of silver = 0.0478 moles x 107.87 g/mol = 5.15 grams.

Hence, the mass of wire that reacted to silver nitrate solution is 5.15 grams.

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I think it is the question:

A copper wire with a mass of 1.52 grams reacted with silver nitrate solution. If the balanced chemical equation and the molar ratio between copper and silver nitrate are provided, how can you determine the mass of wire that reacted?

I understand that you're looking for clarification on the balanced chemical equation and the concept of impurities. Let's break it down.

1. Balanced chemical equation:

The given balanced equation is:

6Fe2+ + Cr2O72- + 14H+ → 6Fe3+ + 2Cr3+ + 7H2O

To understand why there are 6 moles of Fe2+, you need to recognize that the coefficients in a balanced chemical equation represent the stoichiometric ratios between reactants and products. In this redox reaction, the Fe2+ ions are being oxidized to Fe3+ ions, and the Cr2O72- ions are being reduced to Cr3+ ions. The balanced equation is derived through balancing the charges and atoms on both sides of the equation, ensuring that the number of electrons transferred in the redox process is equal.

2. Impure sample X:

The problem states that the sample X is an impure sample of FeSO4.7H2O. This means that the sample contains FeSO4.7H2O as well as other substances (impurities) which do not participate in the reaction. These impurities do not affect the stoichiometry of the reaction but may contribute to the mass of the sample. The goal of the problem is to determine the mass of FeSO4.7H2O in the sample, disregarding the impurities.

Now, let's carry out the calculations to find the mass of FeSO4.7H2O in the sample X:

1. From the balanced equation, we know that 6 moles of Fe2+ react with 1 mole of Cr2O72-.

2. Calculate the moles of Cr2O72- used in the reaction from the volume and concentration of K2Cr2O7 solution:

Moles of Cr2O72- = Volume (dm^3) × Concentration (mol/dm^3)

Moles of Cr2O72- = 0.0213 dm^3 × 0.0150 mol/dm^3 = 3.195 × 10^-4 mol

3. Calculate the moles of Fe2+ in the 25.0 cm^3 aliquot of the 250 cm^3 FeSO4 solution:

Moles of Fe2+ = 6 × Moles of Cr2O72-

Moles of Fe2+ = 6 × 3.195 × 10^-4 mol = 1.917 × 10^-3 mol

4. Calculate the moles of Fe2+ in the entire 250 cm^3 FeSO4 solution:

1.917 × 10^-3 mol (in 25.0 cm^3) × (250 cm^3 / 25.0 cm^3) = 0.01917 mol

5. Calculate the mass of FeSO4.7H2O in the sample X:

Mass = Moles × Molar mass

Mass = 0.01917 mol × (151.91 + 7 × 18.015) g/mol = 0.01917 mol × 278.015 g/mol = 5.33 g (approximately)

Thus, the mass of FeSO4.7H2O in the impure sample X is approximately 5.33 g.