What value must you identify before measuring the absorbance of your diluted solutions?
a.????max
b.molar absorptivity
c.path length
d.concentration of spinach extract solution

Given the following two reactions at 298 K and 1 atm, the true statement is that the ΔH for the overall reaction is equal to the sum of the ΔH for the two individual reactions.

This can be determined by using Hess's Law, which states that the enthalpy change of a reaction is equal to the sum of the enthalpy changes of the individual steps in the reaction. In this case, the overall reaction can be written as:

N₂(g) + (3/2)O₂(g) → 2NO₂(g)

This can be obtained by adding the two given reactions together:

N₂(g) + O₂(g) → 2NO(g) ΔH₁

2NO(g) + O₂(g) → 2NO₂(g) ΔH₂

----------------------------------------------

N₂(g) + (3/2)O₂(g) → 2NO₂(g) ΔH₁ + ΔH₂

Therefore, the ΔH for the overall reaction is equal to the sum of the ΔH for the two individual reactions:

ΔH = ΔH₁ + ΔH₂

This is the true statement for the given reactions at 298 K and 1 atm.

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The 3.50 moles of iron with the chemical formula Fe contain there are  2.1 × 10²⁴ atoms of iron.

Iron's molecular weight is Fe = 3.50 moles.

The number of the moles of the material Equals mass / molar mass

The material has 6.022 x 1023 atoms per mole.

The formula for the Avogadro number is 6.022 1023. The letter Na serves as its emblem.

Fe = 3.50 x 6.022 x 1023 atoms, or 3.50 moles, of iron.

The iron's 3.50 moles (Fe = 2.1 1024 atoms)

A chemical formula is a shorthand representation of a chemical compound using symbols and numerical subscripts to indicate the types and number of atoms present in a molecule. Chemical formulas are used to describe the composition of substances and to predict their behavior in chemical reactions.

The symbols used in a chemical formula represent the elements present in the molecule, and the subscripts indicate the number of atoms of each element in the molecule. For example, the formula for water is H2O, which means that each molecule of water contains two hydrogen atoms (H) and one oxygen atom (O). Chemical formulas can be written for simple compounds, such as water, or complex molecules, such as proteins or DNA.

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When white light from an incandescent lamp is passed through a red filter and then a green filter, only green light will be visible. The reason behind this is the absorption of all colours of white light except green light, by the red filter.

The red filter blocks other wavelengths of white light except for red wavelengths. So, when the red filter is applied, only the red wavelengths pass through it. As a result, the white light becomes reddish. The green filter, on the other hand, has the opposite effect. All wavelengths of white light except for green light are absorbed by the green filter. So, the white light passing through the green filter appears greenish. Only green light would be visible since the red filter only allows red wavelengths to pass through and the green filter only allows green wavelengths to pass through. The light will appear green since only the green colour can pass through the green filter.

Therefore, only green light would be observed if white light from an incandescent lamp were passed through a red filter and then through a green filter.

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Water has a lower density in its solid state than in its liquid state because of the formation of air pockets in the solid phase as a result of hydrogen bonding. The abnormal expansion of water upon freezing is what is known as, and it is crucial for aquatic life.

The ability of water molecules to attract other water molecules is referred to as cohesion.

A robust and flexible lattice of water molecules is created when several water molecules form hydrogen bonds with one another. High surface tension results from this. Water striders may move across the water's surface thanks to surface tension.

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Answer:The density of the solid state is less than the density of the liquid state

Explanation:

If cal is titrating 52.5 ml of 0.304 m hbr with 0.344 m ba(oh)2. The amount of ml of ba(oh)2 that cal need to add to reach the equivalence point is :  92.79 ml.

In order to solve this problem, we can use the following equation that relates the moles of acid to the moles of base:

moles of acid = moles of base

We can rearrange this equation to solve for the volume of base needed to reach the equivalence point:

volume of base = moles of acid / concentration of base

First, let's calculate the number of moles of HBr in the solution:

moles of HBr = volume of HBr x molarity of HBr

moles of HBr = 52.5 ml x 0.304 mol/L

moles of HBr = 15.96 mmol

Since the reaction between HBr and Ba(OH)2 is a 1:2 acid-base reaction, we know that the number of moles of Ba(OH)2 needed to reach the equivalence point is twice the number of moles of HBr:

moles of Ba(OH)2 = 2 x moles of HBr

moles of Ba(OH)2 = 2 x 15.96 mmol

moles of Ba(OH)2 = 31.92 mmol

Finally, we can use the equation above to calculate the volume of Ba(OH)2 needed:

volume of Ba(OH)2 = moles of HBr / concentration of Ba(OH)2

volume of Ba(OH)2 = 31.92 mmol / 0.344 mol/L

volume of Ba(OH)2 = 92.79 ml

Therefore, Cal would need to add 92.79 ml of 0.344 M Ba(OH)2 to reach the equivalence point.

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Yeast uses fermentation to produce carbon dioxide (CO2) as a byproduct of its metabolic process.

Fermentation is an anaerobic process, which means it occurs in the absence of oxygen. During fermentation, yeast breaks down sugar molecules into pyruvate molecules through a process called glycolysis. Pyruvate is then converted into CO2 and ethanol (in the case of alcoholic fermentation) or lactic acid (in the case of lactic acid fermentation) through a series of chemical reactions.

The CO2 produced during fermentation is the reason why bread dough rises and beer becomes carbonated. Therefore, yeast relies on fermentation to produce CO2 as an important component of its metabolism.

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The energy of each orbital is the quantity that needs to be preserved when orbitals are recombined. The energy of each orbital is option b, which is the right response.

The energy of each orbital is conserved when two or more orbitals come together to form a molecular orbital. The conservation of orbital symmetry refers to this energy conservation. The combined energies of the original orbitals will be used to determine the energy of the resulting molecular orbital. This means that the energy of the molecular orbital will fall somewhere between the energies of the original orbitals if they are not equal.

When orbitals combine again to form a molecular orbital, the size, quantity, and energy disparities between the orbitals may all change. However, as required by the law of conservation of energy, the system's overall energy is always conserved.

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Answer:

30

Explanation:

A mass number indicates the total number of protons and neutrons. An element is defined by its number of protons, however neutrons can vary (this is what causes isotopes). By definition, iron (Fe) has 26 protons. Since the mass number is the number of protons + the number of neutrons, the number of neutrons is the mass number - the number of protons, in this case 56-26=30

A Fe2+ ion has a positive charge (but its number of protons can't change without it becoming a different element) so since each proton is +1 to charge and each election is -1, to get a +2 charge, there must be 2 more protons than electrons, so a Fe2+ ion has 24 electrons, but this does not affect the mass number or the number of protons.

Answer:

30

Explanation:

edge2023

The analytical method to determine the concentration of a solution is called titration.

In this method, a solution of unknown concentration is reacted with a solution of known concentration, called a titrant, until a reaction endpoint is reached. The reaction is usually monitored by adding an indicator to the solution, which changes color when the endpoint is reached.

The volume of the titrant used to reach the endpoint is used to calculate the concentration of the unknown solution using stoichiometry and the known concentration of the titrant. Titration is commonly used in chemistry to determine the concentration of acids, bases, and other chemical species in a solution.

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The  three subatomic particles of the atom are protons, neutrons and electrons. The example of atom is Hydrogen, an example of a molecule is oxygen (O2) and an example of a compound is water (H2O).

A particle called an atom has a nucleus made up of protons and neutrons that is encircled by an electron cloud. The fundamental unit of the chemical elements is the atom, and the protons in an atom serve as a means of differentiating one chemical element from another. The electromagnetic force pulls an atom's electrons towards the protons in its atomic nucleus. The nuclear force draws the protons and neutrons in the nucleus together. The electromagnetic force that keeps positively charged protons apart is typically weaker than this force. The electromagnetic force that repels objects can occasionally outweigh the nuclear force. The nucleus breaks in this instance, leaving behind several parts.

1. The three subatomic particles of the atom are protons (positively charged), neutrons (neutral charge), and electrons (negatively charged).

2. Atoms are the basic unit of matter, composed of protons, neutrons, and electrons. Molecules are two or more atoms bonded together, while compounds consist of two or more different molecules that are chemically bonded.

3. A molecule is composed of two or more atoms bonded together, while a compound is composed of two or more different molecules that are chemically bonded.

4. An example of an atom is hydrogen, an example of a molecule is oxygen (O2), and an example of a compound is water (H2O).

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Answer:

mobile electrons

Explanation:

The particles that carry charge through wires in a circuit are mobile electrons. The electric field direction within a circuit is by definition the direction that positive test charges are pushed. Thus, these negatively charged electrons move in the direction opposite the electric field.

Answer:

I think its electrons..

if it is right then pls mark brainliest!

0.0986 moles of C₇H₁₆ (heptane) must be reacted to transfer -474.9 kJ of heat.

To determine the number of moles of C₇H₁₆ (heptane) that must be reacted to transfer -474.9 kJ of heat, we can use the following formula:

Q = n∆H

Where Q is the heat transferred, n is the number of moles, and ∆H is the enthalpy change of the reaction.

Rearranging the formula to solve for n, we get:

n = Q/∆H

Substituting the given values into the formula, we get:

n = -474.9 kJ/(-4815.7 kJ)

n = 0.0986 moles

Therefore, 0.0986 moles of C₇H₁₆ (heptane) must be reacted to transfer -474.9 kJ of heat.

It is important to note that the negative sign in front of the heat transferred and the enthalpy change indicates that the reaction is exothermic, meaning that heat is released during the reaction.

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The vapor pressure of the mixture at 80°C is 285.9 mmHg. The vapor pressure of a mixture can be calculated using Raoult's law, which states that the vapor pressure of a solution is equal to the sum of the vapor pressures of each component multiplied by its mole fraction.

In this case, we have a mixture of hexane and heptane with mole fractions of 0.35 and 0.65, respectively. We can use the Antoine equation to calculate the vapor pressures of each component at 80°C:

P_hexane = 10^(6.89272 - (1203.531)/(80 + 219.888))
P_hexane = 374.6 mmHg

P_heptane = 10^(6.90080 - (1268.115)/(80 + 216.578))
P_heptane = 233.5 mmHg

Using Raoult's law, we can calculate the vapor pressure of the mixture:

P_total = (0.35)(374.6) + (0.65)(233.5)
P_total = 285.9 mmHg

Therefore, the vapor pressure of the mixture at 80°C is 285.9 mmHg.

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The pKa for the N-terminal amino group of the peptide K-T-I-D is 10.19. The correct option is D.

This can be calculated by taking into account the individual pKa values of each amino acid residue, which are: K = 9.74, T = 10.5, I = 10.76, and D = 3.9.

The pKa of the N-terminal amino group of a peptide can be calculated using the Henderson-Hasselbalch equation:

pKa = pH + log([A-]/[HA])

where pH is the pH of the solution, [A-] is the concentration of the conjugate base (deprotonated form) of the amino group, and [HA] is the concentration of the protonated form of the amino group.

In the case of the peptide K-T-I-D, we can assume that the N-terminal amino group has a pKa value of around 9.7. Therefore, at a pH below 9.7, the amino group will be mostly protonated, and at a pH above 9.7, the amino group will be mostly deprotonated.

The N-terminal amino group of a peptide is a primary amine group, which can act as a weak base and accept a proton (H+) to become a positively charged ion. The pKa value of the N-terminal amino group varies depending on the specific peptide sequence and its environment. However, a commonly used approximation is to assume that the pKa value of the N-terminal amino group is around 9.7.

Therefore, the closest answer option to this approximation is option D, 10.19.

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The solubility of methane in hexane is very low. Methane is slightly soluble in hexane and only dissolves in small amounts, with a maximum solubility of 8 mL of methane per 100 mL of hexane.

The solubility of methane in hexane is very low because methane is a gas and hexane is a liquid, and gases are generally not very soluble in liquids. Additionally, methane is a nonpolar molecule and hexane is a nonpolar solvent, meaning that they do not have strong interactions with each other and will not readily dissolve. Therefore, the solubility of methane in hexane is very low and the two substances will not mix well together.

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Answer:

Lower

Explanation:

I'll assume the "z" refers to the number of H2O molecules associated with the compond, which I'll call "X."

The hydrate of X is X*z(H2O).

Let's assume that the original hydrate was X*10(H2O)

Heating a hydrate drives off the (H2O) molecules.   z is often great than 1.  Let's assume the calculated value of z after heating 6:  X*6(H2O)  This would be calculated based on the reduction in mass after all the water left the hydrate as a gas.  Enough mass was lost to conclude that the hydrate had lost 6 H2O groups: therefore X*6(H2O).

If the hydrate were heated for only 5 minutes instead of 10, it is likely that not all of the H2O molecules were removed, so the remaining compound wound still have H2O groups left.  But if 4 remained on each molecuale becuse the heat tikme was cut back, then the calculated value for z would be too low.

Of the options:

The calculated value for z was lower than the actual value for z.

O lower

O equal to

O higher

The reduced heating cycle would not have removed all the H2O groups, so the final mass would have been higher, leading one to concluded that there were fewer H2O groups in the original molecule.  I.e., the calculated value for z would be too low.  

When a hydrate is not heated for a long enough time, not all the water is removed. This causes the calculated 'z' value, or the number of water molecules in the hydrate, to be higher than the actual value. The researchers' impatience during the experiment thus led to a falsely elevated 'z' value.

In experiments involving hydrates, heating is a crucial step because it removes the stored water inside, allowing the calculation of the 'z' value, which refers to the number of water molecules present in the formula of the hydrate. When the hydrate is not heated for enough time, not all the water is removed. Therefore, the mass of the hydrate measured after heating will be greater than it should be, meaning that the calculated 'z' value will be higher than the actual 'z' value. So, the impatience of the researchers led to an incorrect 'z' value that is higher than the actual one.

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Calcium chloride is an ionic compound that is formed by the reaction of calcium metal with chlorine gas. In contrast, calcium and chlorine are both elements that exist as atoms, with calcium being a metal and chlorine being a nonmetal.

The difference in properties between the reactants and products can be explained in terms of their bonding and structure.

In the reaction between calcium and chlorine, electrons are transferred from calcium atoms to chlorine atoms to form calcium ions (Ca2+) and chloride ions (Cl-). This type of bonding, known as ionic bonding, results in the formation of an ionic compound in which the ions are held together by strong electrostatic forces of attraction.

In contrast, the properties of calcium and chlorine are determined by their atomic structure and the types of bonding that exist within their molecules.

Calcium is a metallic element, which means that it has a strong tendency to lose electrons and form cations.

Chlorine, on the other hand, is a nonmetallic element that has a strong tendency to gain electrons and form anions.

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11.95 grams of K2SO4 are produced.

The balanced chemical equation is:

2KOH + H2SO4 -> K2SO4 + 2H2O

We need to determine the amount of K2SO4 produced when 25g of H2SO4 reacts with 7.7g of KOH.

First, we need to determine which reactant is limiting. We can do this by calculating the number of moles of each reactant and comparing them to the stoichiometric ratio in the balanced equation.

Moles of H2SO4 = 25g / 98.08 g/mol = 0.2547 mol

Moles of KOH = 7.7g / 56.11 g/mol = 0.1372 mol

According to the balanced equation, the stoichiometric ratio of KOH to H2SO4 is 2:1. This means that 1 mole of H2SO4 reacts with 2 moles of KOH.

Since we have less KOH than the stoichiometric amount required to react with all the H2SO4, KOH is the limiting reactant. This means that all the KOH will be consumed in the reaction before all the H2SO4 is used up.

To determine the amount of K2SO4 produced, we can use the amount of limiting reactant (KOH) and the stoichiometric ratio from the balanced equation.

Moles of K2SO4 produced = 0.1372 mol KOH x (1 mol K2SO4 / 2 mol KOH) = 0.0686 mol K2SO4

Finally, we can convert moles of K2SO4 to grams using the molar mass of K2SO4.

Mass of K2SO4 produced = 0.0686 mol x 174.26 g/mol = 11.95 g

Therefore, 11.95 grams of K2SO4 are produced.

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As NADH gives up its hydrogen to transporter 1 in the Electron Transport Chain (ETC), NADH is oxidized.

This means that it loses electrons, which are transferred to transporter 1 and subsequently passed along the ETC. The oxidation of NADH is an important step in cellular respiration, as it provides the energy needed to drive the production of ATP molecules.

The energy released by the transfer of electrons along the ETC is used to pump protons across the inner mitochondrial membrane, creating a proton gradient that drives the synthesis of ATP. Once NADH has donated its electrons, it is converted back into NAD+ and can be used again in glycolysis or the citric acid cycle to produce more ATP.

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When solutions of NaCl and AgNO₃ are mixed, a precipitate of AgCl forms.

 NaCl + AgNO3 → AgCl + NaNO3

A precipitate is a solid that is produced in a chemical reaction or as a product of a reaction in a solution. Precipitates come in many shapes and sizes, ranging from fine powders to enormous chunks.NaCl is a chemical compound that is also known as sodium chloride. It is commonly referred to as table salt.

AgNO₃ is a silver nitrate chemical compound. The two compounds are soluble in water. When they are mixed, they react to form AgCl, which is a precipitate.A chemical reaction occurs when a mixture of two solutions forms AgCl. NaCl and AgNO₃ are dissolved in water, which is the solvent.

AgCl precipitates out of the solution as a white solid when the solutions are combined. This happens because AgCl is insoluble in water. So, when NaCl and AgNO₃ are combined, AgCl precipitates out. Hence, the correct option is a precipitate of AgCl forms.

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The appropriate reagents for each reaction are

1. [tex]H_{2}[/tex], Pd/C

2. [tex]H_{2}O[/tex], [tex]H_{2}SO_{4}[/tex]

3. HBr

4. [tex]H_{2}SO_{4}[/tex] heat

5. mCPBA

6. NaOMe

7. [tex]Br_{2}[/tex]

Orgаnic trаnsformаtion involves the conversion of one substrаte into аnother by the use of inorgаnic/orgаnic reаgents. The reаction scheme under considerаtion here involves vаrious trаnsformаtions on cyclopentene/cyclopentаnol. The trаnsformаtion involves oxidаtion, hydrаtion, dehydrаtion epoxide formаtion, аnd dihydroxylаtion.

Your question is incomplete, but most probably your full question can be seen in the Attachment.

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The true statement about the number of signals in a 1H NMR spectrum is that it indicates the number of different kinds of protons.

In 1H NMR spectroscopy, the number of signals corresponds to the number of chemically different types of protons in a molecule. Each signal represents a unique electronic environment for the protons, which is determined by factors such as the chemical bonds and functional groups present in the molecule.

The other statements are not true in regards to the number of signals in a 1H NMR spectrum. The number of signals does not indicate the electronic environment of neighboring protons, the number of neighboring protons, the electronic environment of absorbing protons, or the number of protons in the signal.

In conclusion, the number of signals in a 1H NMR spectrum indicates the number of different kinds of protons in a molecule, each with a unique electronic environment.

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The ABC step is slow is the correct option as the formation of a carbocation is the slowest step in the reaction.

So, carbocation formation is the rate-determining step of a unimolecular substitution reaction.

Carbocation is a type of intermediate species that is involved in the rate-determining step of unimolecular substitution reactions.

The formation of a carbocation is the slowest step in this reaction, and that is why it is the rate-determining step.

The given answer option “The ABC step is slow” is therefore correct.

Explanation:
A carbocation is a cation with a carbon atom that has a positively charged carbon atom.

A carbocation forms due to the loss of an electron pair from the carbon atom, leaving a vacant orbital that is capable of accepting an electron pair.

Carbocations are high in energy and are unstable.
In a unimolecular substitution reaction, carbocation formation is the rate-determining step because the reaction rate depends on the stability of the carbocation.

As the carbocation formed is highly unstable and energy is required to create it, it is the rate-determining step.
Carbocation formation is a reversible process, which means that it doesn’t readily occur.

The nucleophile is too weak to attack without a carbocation present is incorrect because nucleophiles are strong and attack positively charged carbocations.

Solvents can act as nucleophiles but it is not true for all reactions.

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The volume of hydrogen gas produced is 1.79 L.

To determine the volume of hydrogen gas produced, we first need to balance the chemical equation for the reaction between zinc (Zn) and sulfuric acid (H₂SO₄)

Zn + H₂SO₄ → ZnSO₄ + H₂

The balanced equation shows that one mole of zinc reacts with one mole of sulfuric acid to produce one mole of hydrogen gas.

Next, we need to calculate the number of moles of zinc and sulfuric acid that react.

molar mass of Zn = 65.38 g/mol

molar mass of H₂SO₄ = 98.08 g/mol

moles of Zn = 5.00 g / 65.38 g/mol = 0.0764 mol

moles of H₂SO₄ = 8.00 g / 98.08 g/mol = 0.0816 mol

Since the reaction is 1:1, the number of moles of hydrogen gas produced is also 0.0764 mol.

Now, we can use the ideal gas law to calculate the volume of hydrogen gas produced: PV = nRT

where P is the pressure of the gas (in atm), V is the volume of the gas (in L), n is the number of moles of the gas, R is the ideal gas constant (0.0821 L atm/mol K), and T is the temperature of the gas (in K).

We are given the pressure (730.0 mmHg), which we need to convert to atm: 730.0 mmHg = 0.958 atm

We are also given the temperature (22.0 °C), which we need to convert to Kelvin.

22.0 °C + 273.15 = 295.15 K

Now we can plug in the values and solve for V.

V = nRT / P

= (0.0764 mol)(0.0821 L atm/mol K)(295.15 K) / 0.958 atm

= 1.79 L

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There are 7.253 x 10^24 H atoms in 17.5 g (NH4)2C2O4.

Avogadro's number is the number of atoms, molecules, or particles in one mole of a substance, which is approximately 6.022 x 10^23.

To determine the number of H atoms in 17.5 g (NH4)2C2O4, we need to first calculate the number of moles of (NH4)2C2O4 using its molar mass and then use the mole ratio between H atoms and (NH4)2C2O4.

The molar mass of (NH4)2C2O4 can be calculated as follows:

Molar mass of NH4 = 14.01 g/mol

Molar mass of C2O4 = 2 * 12.01 g/mol + 4 * 16.00 g/mol = 88.04 g/mol

Molar mass of (NH4)2C2O4 = 2 * molar mass of NH4 + molar mass of C2O4

= 2 * 14.01 g/mol + 88.04 g/mol

= 116.06 g/mol

Number of moles of (NH4)2C2O4 = mass / molar mass

= 17.5 g / 116.06 g/mol

= 0.1507 mol

The mole ratio between H atoms and (NH4)2C2O4 is 8:2, which means that there are 8 H atoms for every 2 (NH4)2C2O4 units. Therefore, we can calculate the number of H atoms as follows:

Number of H atoms = 8 * Avogadro's number * number of moles of (NH4)2C2O4

= 8 * 6.022 x 10^23 * 0.1507

= 7.253 x 10^24 H atoms

Therefore, there are approximately 7.253 x 10^24 H atoms in 17.5 g (NH4)2C2O4.

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The refrigerant that is banned under the Montreal Protocol is CFCs. The correct answer is A.

The Montreal Protocol is an international agreement that was established in 1987 to help protect the ozone layer by phasing out the production and use of ozone-depleting substances.

CFCs, or chlorofluorocarbons, are one of the main substances that have been banned under the Montreal Protocol due to their significant impact on the ozone layer. On the other hand, propane (option B), isopentane (option C), and HFCs (option D) are also refrigerants, they are not banned under the Montreal Protocol.

Therefore, the correct answer is A. CFCs.

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Both the carbon-nitrogen-oxygen (CNO) cycle and proton-proton fusion are two distinct ways that stars harness nuclear fusion to create energy. The mechanism is determined by the star's mass and temperature.

The main method of generating energy in stars with low to medium masses, like our Sun, is proton-proton fusion. Helium-4 is created through the fusion of protons from hydrogen atoms. In this reaction, two protons combine to create a deuterium nucleus, which subsequently interacts with a third proton to create helium-3. Eventually, the fusion of two helium-3 nuclei to generate helium-4 results in the release of two protons. A significant quantity of energy is released during this process in the form of gamma rays, which eventually reach the star's surface before being expelled into space as visible light and other types of electromagnetic radiation.

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The estimated number in this measurement is 203.5mm. This measurement is an example of a precise number, as it is a very specific value that was measured by a ruler graduated in millimeters.

This means that the measurement is accurate to the nearest millimeter, which is the smallest unit of measure that can be reliably measured with a ruler. The estimated number in this measurement is 203.5mm because it is an exact value, and not just an approximation.

It is important to use precise measurements when measuring objects, as this ensures accuracy and ensures that the results obtained are reliable. This is especially important when measuring objects for scientific purposes, as small inaccuracies can lead to incorrect results. As a result, it is important to use precise measurements when measuring objects to ensure accuracy.

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Answer:

8.09 moles of ethane

Explanation:

To calculate the number of moles of ethane, we need to use Avogadro's number, which is 6.022 x 10^23 molecules per mole. We can use this to convert the given number of molecules into moles.

Number of moles = Number of molecules / Avogadro's number

Number of moles of ethane = 4.87 x 10^24 / 6.022 x 10^23

Number of moles of ethane = 8.09 moles (rounded to two decimal places)

Thus, 8.09 moles of ethane contain 4.87x10^24 molecules of ethane.