How many atoms are there in 1.63 moles of Na? Show your work.

The percentage of the water that can be found to be present is 36.6%.

We know that the mass percent of the water that is present can be obtained from the information that we have in the question that we have in this case. We can see from the question that has been asked that we have that;

Mass of the wet soil = 765 g

Mass of the dry soil =  580 g

Mass of the water = 765 g - 580 g

= 280 g

The percentage of the water that is contained can now be obtained by the use of the process;

280/765 * 100/1

= 36.6%

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Answer:

This is a single displacement or single replacement reaction. In this reaction, aluminum (Al) displaces copper (Cu) from its compound copper sulfate (CuSO4) to form aluminum sulfate (Al2(SO4)3) and copper metal (Cu). The general form of a single displacement reaction is:

A + BC → AC + B

where A is a more reactive metal than B, and A displaces B from its compound BC to form AC and B. In this case, aluminum is more reactive than copper and it displaces copper from copper sulfate.

The answer to the sixth question is emissions of sulphur oxide. Option b is correct. The answer to the seventh question is biological magnification. Option d is correct.

The premise of the 1990 amendments of the Clean Air Act of 1972 was to address the issue of air pollution and its detrimental effects on our health and our environment. The amendments were passed to establish a comprehensive program to reduce air pollution by setting emission standards for industries, requiring the use of cleaner technologies, and enforcing penalties for violations ofthe same.

Biological magnification, is more commonly taught in our schools as biomagnification, and is the process by which certain substances, such as toxic chemicals, become increasingly concentrated as they move up the food chain. This occurs because organisms at lower levels of the food chain absorb these substances from their environment and these toxic substances are stored in their tissues. When predators prey upon these organisms, they absorb the accumulated substances as well, and the concentration of the substances in their bodies becomes even higher. This process can proceed up the food chain, and in extremely high concentrations of toxic substances of top predators, such as birds of prey and marine mammals.

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The mixture of Na2CO3 and CaCl2 is insoluble because it results in the formation of a precipitate of CaCO3

An insoluble material does not dissolve in water.

The balanced chemical equation for the reaction is:

Na2CO3 + CaCl2 → 2NaCl + CaCO3

In this reaction, sodium carbonate reacts with calcium chloride to form calcium carbonate and sodium chloride.

Calcium carbonate is insoluble in water, so it forms a precipitate, while sodium chloride is soluble in water and remains in solution.

Therefore, The mixture of Na2CO3 and CaCl2 is insoluble because it results in the formation of a precipitate of CaCO3.

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The net ionic equation for the reaction between silver nitrate and potssium carbonate will be : 2Ag+(aq) + CO3^(2-)(aq) → Ag2CO3(s).

To write the net ionic equation, you will first need to write the complete and balanced  ionic equation:

2Ag⁺(aq) + 2NO₃⁻(aq) + 2K⁺(aq) + CO₃²⁻(aq) → Ag₂CO₃(s) + 2K⁺(aq) + 2NO₃⁻(aq)

In this equation, the potassium ions and nitrate ions are spectator ions, and as you might have learnt, they are present in the same form on both the reactant and product sides of the equation. So, you can safely eliminate them from the equation to write the net ionic equation:

2Ag⁺(aq) + CO₃²⁻(aq) → Ag₂CO₃(s)

The net ionic equation shows you only the species that participate in the reaction and undergo a change, which in this case are the silver ions and the carbonate ion. It does not show you the species that are remaning unchanged ,that is spectator ions.

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0.309 grams of the gas will dissolve in 1.0 L of water at 1.5 atm of pressure and 29.6°C.

The solution to the question would be gotten with the use of Henry's law

solubility of a gas in a liquid is directly proportional to the partial pressure of the gas above the liquid. This written as :

C1 / P1 = C2 / P2

where C1 and P1 are the initial concentration and pressure, and C2 and P2 are the final concentration and pressure.

Given:

C1 = 0.875 g

P1 = 4.25 atm

P2 = 1.5 atm

We need to find C2, the amount of gas that will dissolve at the new pressure. We can rearrange the formula and solve for C2:

C2 = (C1 * P2) / P1

Now, substitute the given values:

C2 = (0.875 g * 1.5 atm) / 4.25 atm

C2 = 0.309 g

So, approximately 0.309 grams of the gas will dissolve in 1.0 L of water at 1.5 atm of pressure and 29.6°C.

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Three unidentified weak acids' observed acid dissociation constants are shown in the table as 3, 2, and 1, respectively.

Acids that do not fully dissociate in solution are referred to as weak acids. In other terms, an acid that is weak is one that is not powerful. The degree to which weak acids dissociate determines their strength. The acid gets stronger the more it dissociates. Because it almost entirely dissociates, HCl is a powerful acid.

KCl is a naturally occurring salt that possesses a strong basic cation and a strong acidic anion; none of these cations or anion alter the pH of paper. Its normal pH value is 7.0, which is neutral.

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58.2 g of copper (II) phosphate is equal to 0.153 moles.

To find the number of moles in 58.2 g of copper (II) phosphate, we need to divide the mass by the molar mass of the compound.

The molar mass of copper (II) phosphate can be calculated by adding the atomic masses of copper, phosphorus, and oxygen :

Cu3(PO4)2

Cu: 63.5 g/mol

P: 31 g/mol

O: 16 g/mol (there are 8 oxygen atoms in the molecule)

Molar mass of Cu3(PO4)2 = 3(63.5) + 2(31) + 8(16) = 380.5 g/mol

Now we can find the number of moles:

moles = mass / molar mass

moles = 58.2 g / 380.5 g/mol

moles ≅ 0.153 moles

Therefore, 58.2 g of copper (II) phosphate is equal to 0.153 moles.

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Ignoring the possibility of stereoisomers the following substance is called butane.

Stereoisomers are molecules with the same chemical formula and sequence of bonded atoms but differ in their three-dimensional arrangement in space. They arise due to the presence of one or more chiral centers in the molecule that give rise to non-superimposable mirror images.

The two types of stereoisomers are enantiomers and diastereomers. Enantiomers are mirror images that are non-superimposable, while diastereomers are non-mirror images that are non-superimposable. Stereoisomers can have different physical, chemical, and biological properties and are important in fields such as drug development and organic synthesis.

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Answer: The oxidation state of chlorine (Cl) in ClO– is +1.

Explanation:

To determine the oxidation state of iodine (I) in IO3– and chlorine (Cl) in ClO–, we can use the oxidation state rules.

For IO3– (iodate ion):

The sum of the oxidation states for all atoms in a polyatomic ion equals the charge of the ion. In this case, the charge is -1.

Oxygen typically has an oxidation state of -2.

There are three oxygen atoms in the iodate ion.

Let x be the oxidation state of iodine (I). Then, we can write the equation:

x + 3(-2) = -1

x - 6 = -1

x = +5

The oxidation state of iodine (I) in IO3– is +5.

For ClO– (hypochlorite ion):

The sum of the oxidation states for all atoms in a polyatomic ion equals the charge of the ion. In this case, the charge is -1.

Oxygen typically has an oxidation state of -2.

Let y be the oxidation state of chlorine (Cl). Then, we can write the equation:

y + (-2) = -1

y - 2 = -1

y = +1

The oxidation state of chlorine (Cl) in ClO– is +1.

We need to take 0.15L (150 ml) of the 5M potassium bromide solution and dilute it to 1L with 0.85L of solvent (such as water). So the answer is option B. 0.15 ml.

The molar concentration of a chemical entity in a solution, specifically the amount of a solute per unit volume of solution, has been measured to be its molarity.

We can use the dilution formula to find out how much of the 5 M potassium bromide solution is needed to prepare 1 L of 0.75 M solution. The dilution formula is:

M₁V₁ = M₂V₂

Substituting the values provided in the given problem, we get:

(5 M)*V₁= (0.75 M)(1 L)

Solving for V1, we get:

V₁= (0.75 M)(1 L) / (5 M)

V₁ = 0.15 L

Therefore, we need to take 0.15 L of the 5 M KBr solution and dilute it to a total volume of 1 L to prepare a 0.750 M solution.

To prepare the final solution, we need to add enough solvent (for example, water) to bring the total volume to 1 L. The amount of solvent needed is:

volume of solvent = total volume - volume of concentrated solution

volume of solvent = 1 L - 0.15 L = 0.85 L

Therefore, we need to take 0.15 L of the 5 M KBr solution and dilute it to 1 L with 0.85 L of water.

So the answer is (B) 0.15.

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The approximate age of the rock is 868.6 million years when there was about 16.34 grams of K-40 and 16.34 grams of Ar-40.

Define rock ?

A rock is a naturally occurring solid material composed of one or more minerals or mineraloids. Rocks are classified based on their chemical and mineralogical composition, texture, and other physical properties.

The age of the rock can be estimated using the ratio of K-40 to Ar-40, as K-40 decays into Ar-40 over time with a half-life of about 1.25 billion years.

The equation for the decay of K-40 to Ar-40 is:

K-40 → Ar-40 + beta particle + gamma ray

From the information given, we know that the amount of K-40 in the rock is equal to the amount of Ar-40, which means that half of the original K-40 has decayed into Ar-40. This corresponds to one half-life of K-40.

We can use the half-life of K-40 to calculate the age of the rock:

[tex]t = (ln 2) * (t_{\frac{1}{2} })[/tex]

where [tex]t_{\frac{1}{2} }[/tex] is the half-life of K-40, which is approximately 1.25 billion years.

Plugging in the values, we get:

[tex]t = (ln 2) * (1.25 * 10^9 years)[/tex]

t ≈ 868.6 million years

Therefore, the approximate age of the rock is 868.6 million years.

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The normal boiling point of a 0.22 m NaCl solution is 100.51°C.

What is Boiling Point?

Boiling point is the temperature at which a liquid changes its phase from liquid to gas or vapor at a given pressure. It is the temperature at which the vapor pressure of the liquid becomes equal to the atmospheric pressure or the pressure above the liquid surface. At this temperature, the molecules in the liquid gain enough kinetic energy to overcome the intermolecular forces holding them together, and they escape into the gas phase.

The boiling point elevation is given by the equation:

ΔTb = Kb · m

where ΔTb is the boiling point elevation, Kb is the boiling point constant of water, and m is the molality of the NaCl solution.

Assuming complete dissociation of NaCl, 1 mol of NaCl produces 2 mol of ions. Therefore, the molality of the solution is:

m = moles of solute / mass of solvent in kg

We can assume that the mass of the solvent (water) is equal to the mass of the solution, since the mass of NaCl is negligible compared to the mass of water.

m = 0.22 mol / 0.22 kg = 1 mol/kg

Substituting the values into the equation gives:

ΔTb = 0.51 K·kg/mol · 1 mol/kg = 0.51 K

The normal boiling point of water is 100°C, so the boiling point of the NaCl solution is:

Boiling point = normal boiling point of water + ΔTb = 100°C + 0.51°C = 100.51°C

Therefore, the normal boiling point of a 0.22 m NaCl solution is 100.51°C.

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The mole ratio of acetylene to carbon dioxide is 1:2

Number of moles of acetylene;

26.2 g/26 g/mol

= 1 mole

If 2 moles of acetylene produces 4 moles of carbon dioxide

1 mole of acetylene will produce 1 * 4/2

= 2 moles of carbon dioxide

Mass of carbon dioxide = 2 moles * 44 g/mol

= 88 g

If 2 moles of acetylene reacts with 5 moles of oxygen

1 mole of acetylene reacts with 1 * 5/2

= 2.5 moles

Mass of oxygen = 2.5 moles * 32 g/mol

= 80 g

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The Specific Rate Constant of the reaction  X + 2Y + 3Z → 2L + 4T is 0.25. By using rate law for the above reaction is R = K [Y]² [Z].

The proportionality constant in the equation that defines the link between the rate of a chemical reaction and the concentrations of the reacting chemicals is known as the rate constant, also known as the Specific Rate constant.

From Given Table of Experiments :

Experiment 1

         R = K [Y]² [Z]

1 × 10⁻⁴ = K [0.2]² [0.01]

        K = 1 × 10⁻⁴ / [0.04] [0.01]

        K = 1 ×  10⁻⁴ /  4 × 10⁻⁴

        K = 1 / 4

        K = 0.25

Experiment 2

         R = K [Y]² [Z]

9 × 10⁻⁴ = K [0.6]² [0.01]

        K = 9 × 10⁻⁴ / [0.36] [0.01]

        K = 9 ×  10⁻⁴ / 36 × 10⁻⁴

        K = 9 / 36

        K = 0.25

Experiment 3

         R = K [Y]² [Z]

9 × 10⁻⁴ = K [0.6]² [0.01]

        K = 9 × 10⁻⁴ / [0.36] [0.01]

        K = 9 ×  10⁻⁴ / 36 × 10⁻⁴

        K = 9 / 36

        K = 0.25

Experiment 4

        R = K [Y]² [Z]

36 × 10⁻⁴ = K [0.6]² [0.04]

        K = 36 × 10⁻⁴ / [0.36] [0.04]

        K = 36 ×  10⁻⁴ /  × 10⁻⁴

        K = 36 / 144

        K = 0.25

Therefore, The correct option is (D) 0.25.

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Answer:

The correct answer of this question is transverse and longitudinal waves. Explanation: Given - Sound waves and some earthquake waves are waves. Ocean, light, and other earthquake waves are waves.

Explanation:

if it helped u please mark me a brainliest :))

Answer:

Sound waves and some earthquake waves are longitudinal waves. Ocean, light and other earthquake waves are transverse waves.

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With a steady volume and a temperature rise of 45C, the resultant pressure is 9.06 atm.

Force per unit area is referred to as pressure. The force created when gas molecules in a container collide with the walls is known as pressure in the context of gases. The quantity of gas molecules, their average speed, which is correlated with temperature, and the capacity of the container all affect how much pressure the gas experiences.

We may resolve this issue using the ideal gas law, which stipulates:

PV = nRT

where, P stands for the gas pressure, V represents the gas's volume, the number of moles of the gas is n.

The ideal gas constant, or R, is 0.0821 L atm/mol K.

To find the final pressure, P2, we may rearrange this equation as follows:

P1/T1 = P2/T2

where: the first pressure, P1, Initial temperature is T1. The last temperature, T2, is.

Let's enter the above numbers and calculate P2:

P1 = 8.5 atm

T1 = 25 + 273 = 298 K

T2 = 45 + 273 = 318 K

P2 = P1 * T2 / T1

      = 8.5 atm * 318 K / 298 K

       = 9.06 atm.

With a steady volume and a temperature rise of 45C, the resultant pressure is 9.06 atm.

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To convert moles of copper to grams, we need to use the molar mass of copper, which is 63.55 g/mol.

Grams of copper = moles of copper x molar mass of copper

Grams of copper = 5.699 mol x 63.55 g/mol

Grams of copper = 362.071 g

Therefore, there are 362.071 grams of copper in 5.699 moles of copper.

So there are 361.28 grams in 5.699 moles of copper.

The chemical formula C8H18 and the condensed structural formula CH3(CH2)6CH3, octane is both an alkane and a hydrocarbon. There are numerous structural isomers of octane, which vary in the number and placement of carbon chain branches.

2,2,4-trimethylpentane, also known as iso-octane, is one of these isomers and is used as one of the reference values on the octane rating scale.

In the beginning, the octane rating was calculated by combining fuels made entirely of regular heptane and iso-octane (2,2,4-trimethylpentane, a highly branched octane), and allocating anti-knock ratings of zero for regular heptane and one hundred for pure iso-octane.

This mixture's anti-knock rating would be equal to the iso-octane content's %. A lower or higher octane rating may result from different octane isomers.

Thus, The chemical formula C8H18 and the condensed structural formula CH3(CH2)6CH3, octane is both an alkane and a hydrocarbon. There are numerous structural isomers of octane, which vary in the number and placement of carbon chain branches.

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Answer:

C. The amount of natural gas consumed in the U.S. will remain constant even if the population size changes.

Answer: 0.02894 M

Explanation: the equation for molarity is M=moles/liters

first convert 2.7g of MgCl2 to moles, to get this divide by the molar mass 95.21g/mol

next plug the values into the equation

M= 0.02836mol/0.98L

M=0.02894 M

Answer:

The central atom in the Lewis structure is the least electronegative atom. Bromine is the less electronegative atom than Fluorine. So, Bromine will occupy the central position and four Fluorine atom will surround it.

Answer:

salt

Explanation:

the metal cation will form an ionic compound with the conjugate base of the acid to form a salt

With an acid dissociation constant (Ka) of 0.00361 and a concentration of this weak acid of 0.155 M, the percent ionization is roughly 11.68%.

The percent ionization (% ionization) of a weak acid and its acid dissociation constant (Ka) are connected as follows:

Ka = [tex](H^{+}) (A^{-})[/tex]/(HA)

[tex][H^{+}][/tex]/[HA] x 100% = % ionization

where [tex][H^{+} ][/tex] is the amount of hydrogen ions (measured in M) in the solution, [tex][A^{-}][/tex] is the amount of conjugate base (measured in M), and [HA] is the amount of undissociated weak acid (measured in M).

We can use a quadratic equation to determine the concentration of hydrogen ions at equilibrium given that the weak acid's acid dissociation constant (Ka) is 0.00361.

So, using the formula below, we can determine the weak acid's % ionization:

[tex][H^{+} ][/tex]/[HA] x 100% = % ionization

[tex][H^{+} ][/tex]/c x 100% = % ionization

100% of ionization = (0.0181 M/0.155 M)

Therefore, 11.68% of the acid is ionized.

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0.9792 g of  [tex]O_2[/tex] is produced by the chemical reaction of 3.1 g of ammonium perchlorate.

What is chemical reaction ?

A chemical reaction is a process that leads to the transformation of one set of chemical substances to another.

The balanced chemical equation for the reaction of ammonium perchlorate and the products formed is:

[tex]NH_4ClO_4 \rightarrow N_2 + Cl_2 + O_2 + 2H_2O[/tex]

From the equation, we can see that for every one mole of ammonium perchlorate that reacts, one mole of [tex]O_2[/tex] is produced.

To find the mass of [tex]O_2[/tex] produced by the reaction of 3.1 g of ammonium perchlorate, we need to first calculate the number of moles of ammonium perchlorate present:

molar mass of [tex]NH_4ClO_4 = NH_4 (1 * 4 + 14) + Cl + 4O (16 * 4) = 101.5 g/mol[/tex]

moles of [tex]NH_4ClO_4 = mass / molar mass = 3.1 / 101.5 = 0.0306 mol[/tex]

Since the mole ratio of [tex]NH_4ClO_4[/tex] to [tex]O_2[/tex] is 1:1, the number of moles of  [tex]O_2[/tex]produced is also 0.0306 mol.

Finally, we can calculate the mass of  [tex]O_2[/tex] produced using its molar mass:

molar mass of  [tex]O_2[/tex] = 32 g/mol

mass of  [tex]O_2[/tex] = moles of  [tex]O_2[/tex] × molar mass of  [tex]O_2[/tex]

= 0.0306 mol × 32 g/mol

= 0.9792 g

Therefore, 0.9792 g of  [tex]O_2[/tex] is produced by the reaction of 3.1 g of ammonium perchlorate.

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According to the research, the following reactions are classified between exothermic and endothermic:

They are those processes that lead to the combination or modification of atomic nuclei that produces the release or absorption of energy.

In this sense, endothermic reactions where the energy of the product of the reaction is greater than the energy of the reactants and if the reaction releases energy in the form of heat or light, the process is exothermic.

Therefore, we can conclude that according to the research, in endothermic reactions, elements absorb energy from the system and exothermic reactions, during their development, release energy.

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The pressure inside the balloon is about 0.940 atm.

To calculate the pressure inside the balloon we can use the ideal gas law,

According to the ideal gas law,

PV=nRT

where P= pressure of the gas inside the balloon

          V= volume of the balloon (in L)

          n= number of moles of gas in the balloon

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

          T= temperature of the gas (in K)

According to the question the given values are:

n= 0.488 moles

V=12.4L

T= 291K

Putting the above values in an ideal gas equation we get,

P*12.4=0.488*0.0821*291

Therefore,

P=(0.488*0.0821*291)/12.4

P=0.940atm

Therefore the pressure inside the balloon is 0.940 atm.

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The  low-spin octahedral complex [Co(CN)6]¯, is known to be one that all the 6 cyanide ligands that are said to be placed in an octahedral geometry and the 6 electrons from cyanide ligands that will tend to pair up with the 6 electrons from cobalt's 3d orbitals. So no unpaired electrons is seen this complex.

The complex [Co(CN)6]¯ is one that takes in a coordination number of 6, and cyanide (CN¯) may be a solid field ligand. Thus, the complex may be a low-spin octahedral complex.

The electronic arrangement of Co(II) particle is 3d⁷.

So, Cyanide (CN¯) could be a solid field ligand, which suggests it'll cause the 3d orbitals to match up some time recently moving onto the 4d orbitals, coming about within the arrangement of a low-spin complex.

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Helium does undergo nuclear fusion in the Sun, but it is not the primary process that powers the Sun.

What is Helium?

Helium does undergo nuclear fusion in the Sun, but it is not the primary process that powers the Sun. The fusion of hydrogen into helium in the Sun's core is what generates the majority of the Sun's energy output. This process, known as the proton-proton chain reaction, involves a series of steps that ultimately result in the fusion of four hydrogen nuclei (protons) into one helium nucleus.

However, once helium is produced in the Sun's core through this process, it can undergo further fusion reactions. For example, two helium nuclei can fuse to form beryllium-8, which can then either decay back into two helium nuclei or fuse with another helium nucleus to form carbon-12. These reactions do contribute to the overall energy output of the Sun, but they are not the primary process.

So, in short, helium does undergo nuclear fusion in the Sun, but it is not the primary process that powers the Sun.

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Iron (III) Phosphate is the limiting reagent for this reaction.

Main concepts:

Concept 1: Molar Mass

Concept 2: Mole ratio

Concept 3: Limiting reagent

Concept 1: Molar Mass

To find how these substances react, we'll need to know the Molar Mass of each of the two compounds we're working with.  To find the Molar Mass, add their Atomic Weights from the periodic table:

[tex]M_{CaCO_3} = M_{Ca} + M_{C} + 3*M_{O}[/tex]

[tex]M_{CaCO_3} = (40.08) + (12.01) + 3*(16.00)[/tex]

[tex]M_{CaCO_3} = 100.09 \frac{g}{mol}[/tex]

Or, in other words, [tex]1~\text{mol}~CaCO_{3} = 100.09~\text{g}~CaCO_{3}[/tex]

[tex]M_{FePO_{4}} = M_{Fe} + M_{P} + 4*M_{O}[/tex]

[tex]M_{FePO_{4}} = (55.85) + (30.97) + 4*(16.00)[/tex]

[tex]M_{FePO_{4}} = 150.82 \frac{g}{mol}[/tex]

Or, in other words, [tex]1~\text{mol}~FePO_{4} = 150.82~\text{g}~FePO_{4}[/tex]

Concept 2: Mole ratio

Mole ratios are determined from the Balanced Chemical Equation:

[tex]3~CaCO_3 + 2~FePO_{4} \rightarrow Ca_{3}(PO_4)_{2} + Fe_{2}(CO_{3})_{3}[/tex]

This Equation tells us that 3 moles of  [tex]CaCO_3[/tex]  react with 2 moles of [tex]FePO_{4}[/tex]  to produce 1 mole each of [tex]Ca_{3}(PO_4)_{2}[/tex]  and  [tex]Fe_{2}(CO_{3})_{3}[/tex].

Looking at just the two compounds we're interested in from the question, each time the reaction occurs, we're combining 3 moles of  [tex]CaCO_3[/tex]  with 2 moles of [tex]FePO_{4}[/tex].  So, when the reaction occurs, [tex]3~\text{mol}~CaCO_3 = 2~\text{mol}~FePO_{4}[/tex].

From that equation, two mole ratios can be formed (each is just a reciprocal of the other):

[tex]\dfrac{3~\text{mol}~CaCO_3} {2~\text{mol}~FePO_{4}}[/tex]  and  [tex]\dfrac{2~\text{mol}~FePO_{4}} {3~\text{mol}~CaCO_3}[/tex]

Which mole ratio we'll need depends on which units we need to cancel out.

Concept 3: Limiting reagent

We were given that there are 100 g of Calcium Carbonate  [tex]CaCO_3[/tex].   If it were to completely react, then it would follow the mole ratio for the balanced equation.

First, use the Molar mass to convert from grams to moles, then the mole ratio to convert between moles of one substance to moles of the other.  Finally, use the other substance's Molar mass to convert into grams to find out how many grams of the second substance would be needed to completely react with the first.

[tex]\dfrac{100~\text{g}~CaCO_3}{} * \dfrac {1~\text{mol}~CaCO_3}{100.09~\text{g}~CaCO_3}} *\dfrac{2~\text{mol}~FePO_{4}} {3~\text{mol}~CaCO_3} *\dfrac{150.82~\text{g}~FePO_{4}} {1~\text{mol}~FePO_{4}} =[/tex]

[tex]=100.456~\text{g}~FePO_{4}[/tex] would be needed to completely react the 100 grams of Calcium Carbonate.

Recall that we only have 45 grams of Iron (III) Phosphate, which is not the 100.456g needed.  This means we don't have enough of the Iron (III) Phosphate to completely react all of the Calcium Carbonate.

In other words, the amount of Iron (III) Phosphate is insufficient to use up all of the Calcium Carbonate, and so it is the Iron (III) Phosphate that is holding us back from completing the reaction.

Thus, the Iron (III) Phosphate is the limiting reagent.

Looking at things another way

If we had started by looking at the 45g of Iron (III) Phosphate, and found out how much Calcium Carbonate we would have needed to react it completely, we would have found that we had more than enough Calcium Carbonate.  Therefore, the Calcium Carbonate was not holding us back from completing the reaction, and the Calcium Carbonate is not the limiting reagent.  Observe:

[tex]\dfrac{45~\text{g}~FePO_{4}}{} * \dfrac{1~\text{mol}~FePO_{4}}{150.82~\text{g}~FePO_{4}} *\dfrac {3~\text{mol}~CaCO_3}{2~\text{mol}~FePO_{4}} * \dfrac {100.09~\text{g}~CaCO_3} {1~\text{mol}~CaCO_3} = 44.7956~\text{g}~CaCO_3[/tex]

A word of caution!
While for this particular reaction, roughly the same number of grams of each substance is needed to complete the reaction, this is rarely true.  The Molar Masses and the appropriate Mole ratio must be used to find the amount of each substance needed.