Student A is attempting to prepare 2. 85 L, of 0. 500 M HCl solution. She has

37% HCl by mass from the Aldrich 2. 5 L bottle purchased from Sigma-

Aldrich. Explain how she will achieve this goal (show your calculation)

Answer:

Atoms are complex structures, and scientists use different models or descriptions to explain their behavior and properties. These models have evolved over time as our understanding of the atom has increased.

One reason for the different ways to describe an atom is that atoms have both particle-like and wave-like properties. Early models, such as the Thomson model, viewed atoms as a positively charged sphere with negatively charged electrons scattered throughout. Later models, such as the Rutherford model and Bohr model, introduced the concept of the nucleus and orbiting electrons.

As our understanding of quantum mechanics improved, new models, such as the quantum mechanical model, were developed to better explain the wave-like nature of electrons and their behavior within atoms. This model uses a mathematical approach to describe the probability of finding an electron in a specific location within an atom.

Additionally, different models may be better suited for different purposes. For example, the Bohr model is often used in introductory chemistry courses to explain the concept of energy levels, while the quantum mechanical model is more advanced and can be used to calculate more precise properties of atoms.

In summary, the different ways to describe an atom reflect the evolving nature of scientific understanding, as well as the need for different models to explain different aspects of the atom.

Explanation:

Answer:

MgI2

Explanation:

Mg ion is Mg2+ while I ion is I-

so the formula is MgI2

Taking into account the reaction stoichiometry, 49.41 grams of Na₂S₂O₃ is required to produce 64.3 g NaBr.

In first place, the balanced reaction is:

2 AgBr + Na₂S₂O₃ → Ag₂S₂O₃ + 2 NaBr

By reaction stoichiometry (that is, the relationship between the amount of reagents and products in a chemical reaction), the following amounts of moles of each compound participate in the reaction:

The molar mass of the compounds is:

By reaction stoichiometry, the following mass quantities of each compound participate in the reaction:

The following rule of three can be applied: If by reaction stoichiometry 205.78 grams of NaBr are produced by 158.12 grams of Na₂S₂O₃, 64.3 grams of NaBr are produced by how much mass of Na₂S₂O₃?

mass of Na₂S₂O₃= (64.3 grams of NaBr× 158.12 grams of Na₂S₂O₃) ÷205.78 grams of NaBr

mass of Na₂S₂O₃= 49.41 grams

Finally, 49.41 grams of Na₂S₂O₃ is required.

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The heat energy needed to raise the temperature of 2.11 kg of the cooking oil from 23°C to 191°C is 609960 J.

To calculate the heat energy needed to raise the temperature of the cooking oil, we can use the formula:

Q = m × c × ΔT

where:

Q = heat energy (in joules)

m = mass of oil (in grams)

c = specific heat of the oil (in J/(g°C))

ΔT = change in temperature (in °C)

First, we need to convert the mass of the oil from 2.11 kg to grams:

2.11 kg = 2.11 x 1000 g/kg = 2110 g

Substituting the given values into the formula, we have:

Q = 2110 g × 1.75 J/(g°C) × (191°C - 23°C)

Q = 2110 g × 1.75 J/(g°C) × 168°C

Q = 609960 J

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B) 52.000 amu is the right response because it comes nearest to the calculated average atomic mass.

To calculate the average atomic mass of chromium, we need to take into account the mass and abundance of each of its isotopes. We can use the following formula to calculate the average atomic mass:

Average atomic mass = (mass of isotope 1 x abundance of isotope 1) + (mass of isotope 2 x abundance of isotope 2) + (mass of isotope 3 x abundance of isotope 3) + (mass of isotope 4 x abundance of isotope 4)

Substituting the values given in the problem, we get:

Average atomic mass = (49.946 amu x 0.0435) + (51.941 amu x 0.8379) + (52.941 amu x 0.0950) + (53.939 amu x 0.0236)

Average atomic mass = 2.173027 + 43.592439 + 5.02999 + 1.272404

Average atomic mass = 52.06786 amu

Therefore, the correct answer is B) 52.000 amu, which is the closest value to the calculated average atomic mass.

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The amount of energy produced when 93.5 g of oxygen reacts with 13.2 g of hydrogen is -31,640.8 kJ.T.

When 93.5 g of oxygen reacts with 13.2 g of hydrogen in the reaction 2H2 + O2 → 2H2O, the amount of energy produced is -572 kJ. To calculate this, we can use the following equation:

Energy (in kJ) = -572 x (moles of oxygen) x (moles of hydrogen)

First, we need to find the moles of oxygen and hydrogen. To do this, we need to use the molar mass of each element, which can be found in the periodic table. The molar mass of oxygen is 16 g/mol, and the molar mass of hydrogen is 2 g/mol. Therefore, we can calculate the moles of oxygen as follows:

93.5 g of oxygen / 16 g/mol = 5.84 mol of oxygen

And the moles of hydrogen can be calculated as follows:

13.2 g of hydrogen / 2 g/mol = 6.6 mol of hydrogen

Now, we can plug these values into the equation:

Energy (in kJ) = -572 x (5.84 mol of oxygen) x (6.6 mol of hydrogen) = -31,640.8 kJ

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Answer:

B. 5 to 3

Explanation:

There's 5 O2 and 3 CO2

5:3 or 5 to 3

(It isn't A because of the order it was asked in. it always matters what you put first, so generally speaking,

"A to B" or "B to A" ratio wouldn't be the same.)

To find out if the proposed hypothesis or scientific assumption is true, we must submit it to experimentation or hypothesis testing.

An experience is proposed in which the materials are needed:

1 apple

2 lemon

1. Cut and peel half of the apple and immerse it in cold water to which the juice of 2 lemons is added

2. The other half is left unpeeled exposed to the air

Results:

A. In the dough submerged in water it is observed that it does not darken while it is submerged in the water with lemon

B. In the apple exposed to the oxidation of the air, a noticeable darkening is observed .

Oxygen oxidizes the enzyme phenol oxidase present in the fruit, through complex reactions proteins are formed that darken the surface of the apple.

Lemon delays and prevents darkening

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Translated  question : A high school student has heard that adding a few drops of lemon to the exposed area of ​​food slows the browning process, but how can we scientifically find out if this is true?

The correct statement is that A, B, and C all have different freezing points. This is because the freezing point of a substance depends on the number of solute particles per unit volume of solution. Since A, B, and C each contain different amounts of sucrose, ethanol, and sodium hydroxide, they each have different amounts of solute particles, and therefore different freezing points.

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Tertiary or intermediate colors can be created from color mixing.

In a particular color system like RGB, CMYK (more modern), or RYB[2], a tertiary color or intermediate color is created by combining complete intensity of one primary color with half saturation of another primary color and none of a third primary color (traditional).

For the RGB color wheel and the RYB color wheel, tertiary hues have generic names that vary slightly. The following titles are displayed. Another meaning of tertiary color is offered by color theorists like Moses Harris  and Josef Albers , who propose that tertiary colors are produced by combining complimentary colors or sets of secondary colors, such as orange-green, green-purple, and purple-orange.

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So the total number of moles present in the 52.0-gram sample of Na(s) is 0.8 moles.

How to calculate mole  ?

Divide the sample's mass by its molar mass to determine the total number of moles in a 52.0-gram sample of sodium (Na).

As Na has an atomic mass of 23.0 atomic mass units (amu) and each element has an average of 6.02 x 1023 atoms per mole, Na has a molar mass of 23.0 grams/mole.

The gram-formula mass of Na

which is reported as 65.0 grams/mole, must be used since the inquiry pertains to a sample of Na in its solid state (Na(s)).

moles = mass molar mass moles

= 52.0 g 65.0 g/mol moles

= 0.8 mol

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Carolyn observed a freshwater plant, Elodea, in a small aquarium filled with freshwater on her desk.

In one five-minute period, Carolyn counted 32 bubbles that formed on the plant’s leaves and were released into the water. She then moved the aquarium closer to a sunlit window and observed the Elodea again. In a second five-minute period, Carolyn observed 194 bubbles form and be released by the Elodea into the water.

a. The bubbles released by Elodea signify that the plant is cycling matter because they are evidence of photosynthesis. Photosynthesis is a process by which plants convert light energy from the sun into chemical energy stored in carbohydrates. The bubbles that form and are released from Elodea are oxygen which is a by-product of photosynthesis. The increase in the number of bubbles from 32 to 194 when the aquarium was moved closer to a sunlit window also supports this, as the increased light intensity enables the plant to carry out photosynthesis more quickly and efficiently.
b. The number of gas bubbles produced by Elodea in a five-minute period increased when the aquarium was moved from the desk to the sunlit window because the increased light intensity allows the plant to carry out photosynthesis more quickly and efficiently. Photosynthesis requires light energy from the sun in order to produce carbohydrates, and the increased light intensity allowed the plant to produce more oxygen as a by-product.

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Answer: But

Explanation:
1 carbon atom - meth
2 carbon atoms - eth
3 carbon atoms - prop
4 carbon atoms - but

this needs to be memorised

Molarity of acetic acid = 0.00083 mol/L. Therefore, the percent error between the experimental and theoretical pKa of acetic acid is: Percent error = (experimental pKa - 4.75)/4.75 x 100%

a. To calculate the molarity of acetic acid in vinegar, you need to convert 5% (by mass) acetic acid into moles. To do this, you will use the equation:

Moles of acetic acid = (mass of acetic acid/molar mass of acetic acid) x (density of vinegar)

We can assume that the density of vinegar is 1 g/ml. The molar mass of acetic acid is 60.05 g/mol. So, we can calculate the moles of acetic acid as follows:

Moles of acetic acid = (0.05 g/60.05 g/mol) x (1 g/ml) = 0.00083 mol

To calculate the molarity of acetic acid, we need to divide the number of moles of acetic acid by the volume of vinegar (in liters):

Molarity of acetic acid = 0.00083 mol/L

b. To calculate the pKa of acetic acid, you need to use the measured pH of vinegar. The pH of a solution can be related to the pKa of an acid using the equation:

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

where [A-] is the concentration of the acid’s conjugate base and [HA] is the concentration of the acid itself. The pKa of acetic acid is 4.75. So, the equation above can be rearranged to calculate the concentration of the conjugate base, [A-]:

[A-] = 10^(pKa - pH) x [HA]

Therefore, we can calculate the pKa of acetic acid given the measured pH of vinegar and the molarity of acetic acid:

pKa = pH + log ([A-]/[HA]) = measured pH + log (10^(pKa - pH) x [HA]/[HA]) = measured pH + log (10^(4.75 - measured pH))

c. To calculate the percent error between the experimental and theoretical pKa of acetic acid, we can use the following equation:

Percent error = (experimental - theoretical)/theoretical x 100%

Therefore, the percent error between the experimental and theoretical pKa of acetic acid is:
Percent error = (experimental pKa - 4.75)/4.75 x 100%

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The graphical solution to the above system of inequalities is attached accordingly.

A system of inequalities is a set of two or more inequalities that are considered together. The solution to a system of inequalities is the set of all values that satisfy all the inequalities simultaneously.

To graph the system of inequalities y < 6x + 4 and y > 5x + 4, we first graph the boundary lines y = 6x + 4 and y = 5x + 4.

To graph the line y = 6x + 4:

Plot the y-intercept (0, 4).

Use the slope, rise over run, to find additional points. For example, if we move up 6 units and right 1 unit from the y-intercept, we get the point (1, 10).

Draw a straight line through the points.

To graph the line y = 5x + 4:

Plot the y-intercept (0, 4).

Use the slope, rise over run, to find additional points. For example, if we move up 5 units and right 1 unit from the y-intercept, we get the point (1, 9).

Draw a straight line through the points.

Now we need to shade the area that satisfies the system of inequalities.

To do this, we can choose a test point, such as (0, 0), and plug it into both inequalities:

y < 6x + 4:

0 < 6(0) + 4

0 < 4 (true)

y > 5x + 4:

0 > 5(0) + 4

0 > 4 (false)

Since (0, 0) satisfies the first inequality but not the second, we shade the area below the line y = 6x + 4 but above the line y = 5x + 4.

The shaded area is the region between the two lines, below y = 6x + 4, and above y = 5x + 4.

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Therefore, 8 moles of aluminum would require 12 moles of chlorine to react completely and produce 8 moles of aluminum chloride.

A reaction is a process that leads to the transformation of one set of chemical substances to another. In other words, a chemical reaction is the breaking of chemical bonds in reactants and the formation of new chemical bonds to create products. Chemical reactions involve the rearrangement of atoms and electrons, leading to the formation of new substances with different properties than the original substances.

Here,

The balanced equation is:

2 Al + 3 Cl2 → 2 AlCl3

a. According to the balanced equation, 2 moles of aluminum reacts with 3 moles of chlorine to produce 2 moles of aluminum chloride. Therefore, 4 moles of aluminum chloride would require:

4 moles AlCl3 x (3 moles Cl2 / 2 moles AlCl3) = 6 moles Cl2

So, 4 moles aluminum chloride is equivalent to 6 moles chlorine.

b. Similarly, according to the balanced equation, 2 moles of aluminum reacts with 2 moles of aluminum chloride. Therefore, 1 mole of aluminum chloride would require:

1 mole AlCl3 x (2 moles Al / 2 moles AlCl3) = 1 mole Al

So, 1 mole aluminum chloride is equivalent to 1 mole aluminum.

c. Finally, using the mole ratios from parts (a) and (b), we can determine the number of moles of chlorine that would be produced if 8 moles of aluminum reacted:

8 moles Al x (2 moles AlCl3 / 2 moles Al) x (3 moles Cl2 / 2 moles AlCl3) = 12 moles Cl2

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The capacity of a substance to rotate the polarization plane of an incident light beam.

Chiral molecules are said to be optically active because they can spin the plane of polarisation in a different way by interacting with the electric field in a different way. Generally speaking, optical isomers are molecules that rotate light in different directions.

A polarimeter is used to measure optical activity, which is a chiral molecule's capacity to rotate the plane of plane-polarized light. A grouping of these molecules' optical activity is a macroscopic characteristic that results from their interactions with light.

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The average speed of SO2 molecules at a certain temperature and pressure will be the same as the average speed of chlorine molecules, which is: 0.0380 m/s

At a certain temperature and pressure, chlorine molecules have an average speed of .0380 m/s. Under the same conditions, the average speed of SO2 molecules will be the same. This is because temperature and pressure are constant parameters and do not change the speed of molecules. Therefore, the average speed of SO2 molecules at the same temperature and pressure is .0380 m/s.

To further explain, the temperature is related to the kinetic energy of molecules and the average speed of a molecule is proportional to the square root of its absolute temperature. Therefore, when the temperature is constant, the average speed of the molecules is constant too.

Similarly, pressure is related to the number of collisions between molecules, but it does not have an effect on the average speed of the molecules. Therefore, when the temperature and pressure are constant, the average speed of the molecules is also constant.

In conclusion, the average speed of SO2 molecules at a certain temperature and pressure will be the same as the average speed of chlorine molecules, which is .0380 m/s.

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The combustion reaction of sucrose (C12H22O11) with oxygen (O2) can be represented by the following equation:

C12H22O11 + 12 O2 → 12 CO2 + 11 H2O

From the balanced equation, we can see that 1 mole of sucrose reacts with 12 moles of oxygen to produce 12 moles of carbon dioxide.

The molar mass of sucrose is approximately 342.3 g/mol (12 x 12.01 g/mol + 22 x 1.01 g/mol + 11 x 16.00 g/mol), which means that 84 g of sucrose is equivalent to:

84 g / 342.3 g/mol = 0.2456 moles of sucrose

According to the balanced equation, the combustion of 1 mole of sucrose produces 12 moles of carbon dioxide. Therefore, the combustion of 0.2456 moles of sucrose will produce:

0.2456 moles x 12 moles CO2 / 1 mole sucrose = 2.9472 moles of carbon dioxide

Finally, we can convert moles of carbon dioxide to mass using the molar mass of carbon dioxide, which is approximately 44.01 g/mol. Therefore, the mass of carbon dioxide produced from burning 84 g of sucrose in Skittles would be:

2.9472 moles x 44.01 g/mol = 129.5 g of CO2

So, if you ate an entire bag of Skittles (84 g of sucrose), you would breathe out approximately 129.5 g of carbon dioxide.

Answer:

Covalent compounds are typically liquids or gases at room temperature, although the more complex and the larger the molecule, the greater the chance that it could exist as a solid.

Explanation:

From desch.org

The activation energy is 101, 800J/mol

Activation energy is the minimum amount of energy required to start a chemical reaction by breaking the bonds of the reactant molecules. In other words, it is the energy barrier that must be overcome before a chemical reaction can occur.

Given that;

[tex]ln(k2/k1) = -Ea/R(1/T2 - 1/T1)\\ln(5 * 10^-4/4.9 * 10^-3) = -Ea/8.314(1/318 - 1/336)\\-2.28 = -2 * 10^-5 Ea\\Ea = 2.28/2 * 10^-5\\Ea = 101, 800J/mol[/tex]

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the relative rate of diffusion of NH3 compared to He is 0.485 and NH3 deffuse slower than He

NH3 has a molar mass of 17 g/mol and He has a molar mass of 4 g/mol. We can calculate the relative rate of diffusion of NH3 compared to He using Graham's law of diffusion as follows:

Relative rate of diffusion = (Molar mass of He / Molar mass of NH3) squared

Relative diffusion rate =

[tex] \sqrt{4 g/mol / 17 g/mol)} [/tex]

The relative rate of diffusion is equal to the square root of 0.235.

Diffusion rate relative = 0.485

As a result, the relative rate of diffusion of NH3 versus He is approximately 0.485.

As a result, NH3 diffuses more slowly than He. Similarly, because effusion rate is proportional to square root of molar mass, NH3 will effuse more slowly than He.

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Temperature of the material needs to be measured. Then the equation Q=mcΔT needs to be used, where Q is the heat energy, m is the mass, c is the specific heat capacity and ΔT is the change intemperature.

Material is something that can be seen, felt, and/or interacted with. It is the physical substance of which a thing is composed. Materials can be made up of elements, compounds, and/or mixtures of these. Examples of materials include metals, plastics, rubber, wood, paper, cloth, glass, and water. Each material has unique properties such as strength, weight, color, texture, and durability. The choice of material used in a design or product is important as it affects the cost, performance, and overall success of the item.

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Answer:

The purpose of heating and cooling the metal for several rounds in the experiment is to ensure that it reaches a stable state or equilibrium. This equilibrium state means that the metal has reached a constant temperature and has stopped losing or gaining weight due to chemical reactions. By recording the mass after each round of heating and cooling, scientists can monitor the weight changes and determine when the metal has reached a stable state.

The repeated rounds of heating and cooling also help to reduce errors in the experiment. By conducting multiple rounds of heating and cooling, any residual impurities or gases on the surface of the metal will be removed. This ensures that the metal is in a pure state before measurements are taken, which increases the accuracy of the final results. Additionally, the repeated rounds of heating and cooling allow for any fluctuations in the ambient temperature to be accounted for, further reducing errors in the experiment. Overall, the process of heating and cooling the metal multiple times helps to ensure accuracy and reliability in the experimental results.

Explanation:

The 99% confidence that the true proportion of adults who oppose allowing transgender students to use the bathrooms of the opposite biological population sex is between 0.1626 and 0.2084.

This means that we are 99% confident that the true population proportion of adults who oppose allowing transgender students to use the bathrooms of the opposite biological gender lies between 18.3% and 22.3%.

To construct a 99% confidence interval for the population proportion, we can use the following formula:

confidence interval = sample proportion ± z* (standard error)

Where, sample proportion = proportion of people in the sample who oppose allowing transgender students to use the bathrooms of the opposite biological sex = 730/3941 = 0.1855

z* = the z-score corresponding to a 99% confidence level, which can be found using a standard normal distribution table or calculator. For a two-tailed test at the 99% confidence level, the z-score is 2.576.

standard error = the standard deviation of the sampling distribution of the proportion, which can be calculated using the formula sqrt(p * (1-p) / n), where p is the sample proportion and n is the sample size.

Substituting the values we have:

confidence interval = 0.1855 ± 2.576 * sqrt(0.1855 * (1-0.1855) / 3941)

This simplifies to:

confidence interval = (0.1626, 0.2084)

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The study of heat and energy in relation to various physical transformations and chemical processes is known as thermochemistry. Energy might be released or absorbed throughout the reaction ( exothermic).

Thermochemistry is difficult. Several fictitious terms, like enthalpy, entropy, and the dreaded Gibbs free energy, must be understood. These ideas are difficult to understand and full of traps. Unless you have a fantastic tutor for Cambridge Coaching who can make everything crystal obvious for you.

The law of conservation of energy, the law of conservation of mass, and Hess's law are the three fundamental principles of thermochemistry.

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From the chemical formula of hydrazine, each  patch has two Nitrogen  tittles.  

N2H4 is a tintless and ignitable  liquid with a pungent odor. It's generally used as a reducing agent in chemical  responses and as a rocket fuel.   Each N2H4  patch contains two nitrogen  tittles and four hydrogen  tittles, with a molecular weight of32.04 g/  spook.

The  patch has a direct shape with a bond angle of about 111 degrees between the two nitrogen  tittles.   The nitrogen  tittles in N2H4 have a covalent bond between them, with each nitrogen  snippet  participating three electrons to form a  triadic bond. The two hydrogen  tittles are attached to each nitrogen  snippet through single covalent bonds.   Overall, N2H4 is an important and  protean chemical with  numerous artificial and  exploration  operations.

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The correct statement is "The positioning of all reactants is crucial".

What are the reactants?

The given illustration shows the possible routes of collisions in the reaction CH₂ = CH₂ + HCl → [tex]CH_{3}CH_{2}Cl[/tex].

Regarding the given options, the correct statement is "The positioning of all reactants is crucial".

This is because, in this reaction, the reactants must collide with a specific orientation or positioning in order for the reaction to occur. Specifically, the chlorine atom from HCl must collide with one of the carbon atoms in ethylene (CH₂=CH₂) in a way that allows the bond between the carbon and hydrogen to break and a bond to form between the chlorine and the carbon atom. This type of reaction is known as an addition reaction, and it requires the proper orientation of the reactant molecules for it to occur.

Therefore, the positioning of all reactants is crucial for this reaction to take place.

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After calculating the mass by using the molar mass of calcium (Ca) and Avogadro's number (Nₐ), Rounding to the nearest whole number, the mass of the sample is approximately 365 g.

How to determine the mass of the sample?

To determine the mass of the sample, we need to use the molar mass of calcium (Ca) and Avogadro's number (Nₐ) to convert the number of atoms to mass.

The molar mass of calcium is approximately 40.08 g/mol, which means that one mole of calcium contains 6.022 x 10²³ atoms.

So, first we need to find out how many moles of calcium are in the sample:

moles of calcium = number of atoms / Avogadro's number

moles of calcium = 5.5 x 10²⁴ / 6.022 x 10²³

moles of calcium = 9.13

Now we can use the molar mass of calcium to convert moles to grams:

mass of sample = moles of calcium x molar mass of calcium

mass of sample = 9.13 x 40.08

mass of sample = 365.4 g

Rounding to the nearest whole number, the mass of the sample is approximately 365 g.

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