What is the concentration, in ppb, of
PCB's in a chemical spill, if there
are 6.0 x 10-5 g in 4,600 kg of soil?

Find the expected yield of lead:

The expected yield of lead if 50.0 kg of lead oxide is heated with 50.0 kg of carbon is 46 kg

Calculation:

First and foremost, we must correctly write the equation of reaction in order to answer this issue. This is what it is:

PbO(s) + C(s) → Pb(l) + CO (g)

We continue from here. The limiting reactant should be found, however finding out how many moles of each reactant are present is the only way to do so.

The number of moles is calculated using the formula: the mass of each reactant divided by the molar mass of each reactant.

Mass of PbO is 50kg = 50000g

Molar mass of PBO = 223.20g/mol

The number of moles is thus 50000/223.2 = 224 moles

For carbon, mass is also 50kg = 50000g

Molar mass is 12g/mol

Number of moles of carbon = 50000/12 = 4166.6 moles

We can observe from the number of moles that there are more moles of carbon than PbO. This indicates that the limiting reagent is PbO.

So, in order to determine percentage yield, we employ it.

Since we have a mole ratio of 1 to 1, the number of moles of lead created is equal to the number of moles of lead oxide, which is 224.

The molar mass of lead = 207.20 g/mol

The mass of lead formed = moles of lead x molar mass of lead

The mass of lead formed = 207.20 x 224 =  46,412.8 g = 46 kg

Hence, the expected yield is 46 kg.

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The energy can be identified by their features, characteristics and impacts on the surrounding environment.

If the energy release heat then we can say that it is a thermal energy because it warms the environment whereas if the energy produce light then it is called radiant energy.

If the energy is released from splitting atoms or fusion of atoms so we can say that it is a nuclear energy. If the energy is released from breaking of bonds of atoms and molecules, so it is Chemical energy.

So we can conclude that the energy can be identified by their features, characteristics and impacts on the surrounding environment.

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18 g of silicon-32 will be present in 800 years.

A radioactive half-life refers to the amount of time it takes for half of the original isotope to decay and it's given by

                              [tex]N(t) = N_0 (\frac{1}{2}) ^\frac{t}{t_\frac{1}{2} }[/tex]

where,

[tex]N(t) =[/tex] quantity of the substance remaining

[tex]N_0 =[/tex]  the initial quantity of the substance

[tex]t =[/tex]  time elapsed

[tex]t_1_/_2 =[/tex] the half-life of the substance

From the given information we know:

The initial quantity of silicon-32 is 40 g.

The time elapsed is 800 years.

The half-life of silicone-32 is 710 years.

So, using the calculation above, we can determine how much silicon-32 is left.

                  [tex]N(t) = 40 (\frac{1}{2}) ^\frac{800}{710} \\N(t) = 40 (\frac{1}{2}) ^\frac{80}{71} \\\\N(t) = 18 g[/tex]

Therefore,18 g of silicon-32 will be present in 800 years.

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A student determines the mass of a 100 mL beaker filled with 50 mL of water to be 154.34 grams. After a tablet reacts with the water, the mass including the dissolved tablet is 157.26 grams. 438 grams tablet was left in the beaker after the reaction.

Stoichiometry helps us use the balanced chemical equation to measure quantitative relationships and it is to calculate the amounts of products and reactants that are given in a reaction.

The balanced chemical equation is the equation in which the number of atoms on the reactant side is equal to the number of atoms on the product side in an equation.

Now we have to write the balanced chemical equation

NaHCO₃ + H₂O → NaOH + H₂CO₃

Mass = 157.26 - 154.32

         = 2.92

Volume = 100 + 50 ml

             = 150 ml

Mass of tablet = 2.92 × 150

                        = 438 grams  

Thus from the above conclusion we can say that A student determines the mass of a 100 mL beaker filled with 50 mL of water to be 154.34 grams. After a tablet reacts with the water, the mass including the dissolved tablet is 157.26 grams. 438 grams tablet was left in the beaker after the reaction.

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Principal energy levels describe regions of space where electrons may be found.

the greater the average distance from the nucleus.

The principal energy level of an electron is the shell or orbit in which the electron resides with respect to the nucleus. This level is represented by the principal quantum number n.

The principal quantum number n represents the total relative energy of each orbit. The energy level of each orbit increases as the distance from the nucleus increases. A set of orbitals with the same n value is often called the electron shell.

Only seven energy levels are required to contain all the electrons in any atom of any currently known element. As mentioned earlier, the energy associated with the energy level increases as the distance from the nucleus increases.

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Answer:

2 kg

Explanation:

the half life of cesium is approx 30 years

  60 years is 2 half lives

       8 kg * 1/2 * 1/2 = 2 kg  

Answer:

d. oligomer it is the correct answer also if you would just search that up it pops up

The intermolecular forces, such as hydrogen bonds or van der Waals attractions, which draw one molecule to its neighbors, govern a substance's physical properties. Due to the relatively weak intermolecular forces of attraction, molecular substances typically take the form of gases, liquids, or low melting point solids.

The forces that bind two molecules together are known as intermolecular forces. Intermolecular forces have an impact on physical properties. Strong and weak forces both exist; the stronger the force, the more energy is needed to separate the molecules from one another. As intermolecular forces increase melting, boiling, and freezing points rise.

The following intermolecular forces are listed in order of strength:

It would take very little energy to separate two molecules if they are connected by van der Waals dispersion forces. On the other hand, it requires a lot more energy to separate two molecules that are joined together by ionic bonds.

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Answer:

2.17 moles

Explanation:

50 gm / 22.99 g / mole = 2.17 moles

Answer:

2.17

Explanation:

If the same test, given at different points in time to the same test takers, yields different scores, then the method typically used to assess this source of error is alternate form.

An alternate form or parallel form test is a test which is conducted at different time on the same set of test takers in order to test the reliability of the results obtained.

In conclusion, alternate or parallel form tests is a test of reliability.

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Answer:

See below

Explanation:

[tex]\rule[225]{225}{2}[/tex]

Once hydrogen bonds form between every fourth amino acid in a polypeptide chain, the chain begins to twist into the secondary structure known as a(n) alpha helix.

Amino acids are organic compound. Amino acids contains amine and carboxyl functional group. Amino acids is the building block of life these are the molecules that combine to form proteins.

A unique sequence of amino acids joined by peptide bonds is called polypeptide.

Thus from the above conclusion we can say that Once hydrogen bonds form between every fourth amino acid in a polypeptide chain, the chain begins to twist into the secondary structure known as a(n) alpha helix.

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(2.) A lab assistant Alex test for the presence of X, the balanced chemical equation is CaCO₃ + 2HCl → CaCl₂ + CO₂ + H₂O. (3.) Another lab assistant perform the test, the balanced chemical equation is CaCO₃ + 2NaOH → Ca(OH)₂ + Na₂CO₃. (4.) The Substance X is Calcium carbonate.

The balanced chemical equation is the equation in which the number of atoms on the reactant side is equal to the number of atoms on the product side in an equation.

(2.) To test for the presence of substance X, a lab assistant, Alex, treats a sample of the material with hydrochloric acid. Bubbles of carbon dioxide gas are observed and collected during the test reaction.

The balanced chemical equation is

CaCO₃ + 2HCl → CaCl₂ + CO₂ + H₂O

(3.) Another lab assistant, Jess, disagrees with Alex, and treats a sample of substance X with sodium hydroxide. One of the products of this reaction is a compound called milk of lime (found to be only slightly soluble in water).

The balanced chemical equation is

CaCO₃ + 2NaOH Ca(OH)₂ + Na₂CO₃

The type of reaction is Double displacement reaction

(4.) The lab assistant Alex perform the valid test for substance X because it gives effervescence of bubbles. The substance X is calcium carbonate. When calcium carbonate react with dilute HCl then carbon dioxide gas bubbles is present in it.

Thus from the above conclusion we can say that  (2.) A lab assistant Alex test for the presence of X, the balanced chemical equation is CaCO₃ + 2HCl → CaCl₂ + CO₂ + H₂O. (3.) Another lab assistant perform the test, the balanced chemical equation is CaCO₃ + 2NaOH → Ca(OH)₂ + Na₂CO₃. (4.) The Substance X is Calcium carbonate.

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The reaction is completed by the equation below: [tex]3H_2 + N_2 --- > 2NH_3[/tex]

They are chemical reactions in which two or more molecules react to produce a single product.

In this case, the synthesis reaction is that of ammonia. Molecules of hydrogen gas and nitrogen gas combine to produce ammonia.

The equation of the reaction is as follows: [tex]3H_2 + N_2 --- > 2NH_3[/tex]

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the de Broglie wavelength of the electron moving at a velocity of 3. 0 × 107 m/s is 2.4×10∧-11nm

lambda = h/mv

The de Broglie wavelength is defined as follows: lambda = h/mv, wherein the greek letter lambda represents the wavelength, h is Planck's consistent, m is the particle's mass and v is its pace. One may also explicit mv as the particle's momentum

according to wave-particle duality, the De Broglie wavelength is a wavelength manifested in all the gadgets in quantum mechanics which determines the chance density of locating the item at a given factor of the configuration area. The de Broglie wavelength of a particle is inversely proportional to its momentum

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A wavy pattern of dark and light bands on the bottom of a pond is caused by refraction of light waves through a rough surface; option D.

Destructive interference occur when two waves come in contact with each other and cancel each other out.

Reflection and refraction of light waves can result in destructive interference. An example of destructive interference due to refraction of light is a wavy pattern of dark and light bands on the bottom of a pond.

In conclusion, destructive interference occurs when waves cancel each other out.

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The answer to the question is D.

Tempering Valve should be installed to cool the water.

A tempering valve is also called an anti-scald valve.

The thermostat controls the temperature inside the tank between 120F to 140F.

A thermostat is just a switch that is actuated by temperature. The thermostat will activates one of the elements in response to a "request for heat" when it detects a water temperature below its predetermined point.

At 140 degrees F temperature water can cause a burn to the skin in five seconds.

The Tempering valve is the mixing chamber, where cold water is mixed with hot water.  

It functions as a mixing device, mixing hot and cold water to generate the proper water temperature that is emitted from a certain outlet.

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The combustion of 30.0 g of glucose at room temperature and pressure produces 24.0 L of carbon dioxide.

It is a reaction in which a substance burns with oxygen to form carbon dioxide and water.

Let's consider the combustion of glucose.

C₆H₁₂O₆ + 6 O₂ ⇒ 6 CO₂ + 6 H₂O

First, let's convert 30.0 g of glucose to moles using its molar mass.

30.0 g × 1 mol/180.16 g = 0.167 mol

The molar ratio of C₆H₁₂O₆ to CO₂ is 1:6. The moles of carbon dioxide produced are:

0.167 mol Glucose × (6 mol CO₂/1 mol Glucose) = 1.00 mol CO₂

1 mol of an ideal gas at room temperature and pressure occupies 24.0 L.

The combustion of 30.0 g of glucose at room temperature and pressure produces 24.0 L of carbon dioxide.

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chemical properties and same number of shell

Explanation:

elements in the same group have the same number of eletrons in their outermost shell and hence have the same chemical properties

In the subgranular zone

The amount of energy, in Joules, that the food contains will be 414.8 Joules

According to metrics, 1 kilocalorie = 4184 Joules.

100 Calories = 100/1000 = 0.1 kiloCalories.

0.1 kilocalories = 0.1 x 4184 = 414.8 Joules

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As a reaction proceeds toward equilibrium from reactants to products, the value of Q is Increasing

Equilibrium can exist in chemical processes (the products and reactants are produced at the same rate). In a reversible chemical reaction, chemical equilibrium is the state in which there is no net change in the quantity of reactants or products. When a chemical reaction is reversible, the products react with the original reactants as soon as they are created.

There is no net change in the quantity of the chemicals involved when the two opposing reactions are in equilibrium because they are occurring at identical rates, or velocities. At this point, the reaction may be deemed to be finished, meaning that the maximum amount of reactants to products has been converted under the given reaction conditions.

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The carbon atom reduced in the transformation of chloromethane to methyllithium.

The reaction between chloromethane  and lithium form methyllithium.

[tex]CH_{3} Cl+ 2Li[/tex] → [tex]CH_{3} Li+ LiCl[/tex]

In above reaction, methyllithium is formed by the dispersing of lithium metal and adding chloromethane  .

The carbon atom in chloromethane  is partial positive charge because chlorine is high electronegative atom. The carbon atom in methyllithium is partial negative charge because carbon is more electronegative than lithium.

So, in above reaction two lithium metal donate two electron ( each lithium donate one electron) to the carbon atom(having positive charge) of chloromethane and get negative charge in methyllithium .

The gain of electron is reduction. So,The carbon atom reduced in the transformation of chloromethane to methyllithium.

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The hydrolysis of sucrose to glucose and fructose is exergonic. However, if sucrose is dissolved in water and the solution is kept overnight at room temperature, there is no detectable conversion to glucose and fructose because the activation energy of the reaction is high.

Hence, Option (B) is correct answer.

The minimum amount of energy that must be provided by a reacting molecules to get converted into the product is called Activation energy.

It is expressed as:

[tex]k = Ae^{\frac{-E_a}{RT}}[/tex]

where,

k = rate constant

A = pre-exponential factor

Eₐ = activation energy

R = universal gas constant

T = absolute temperature in K

Thus from the above conclusion we can say that The hydrolysis of sucrose to glucose and fructose is exergonic. However, if sucrose is dissolved in water and the solution is kept overnight at room temperature, there is no detectable conversion to glucose and fructose because the activation energy of the reaction is high.

Hence, Option (B) is correct answer.

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Disclaimer: The question was given incomplete on the portal. Here is the complete question.

Question: The hydrolysis of sucrose to glucose and fructose is exergonic. However, if sucrose is dissolved in water and the solution is kept overnight at room temperature, there is no detectable conversion to glucose and fructose. Why?

A. The change in free energy of the reaction is positive.

B. The activation energy of the reaction is high.

C. The change in free energy of the reaction is negative.

D. This is a hydrolysis reaction, so it requires an input of energy.

E. The free energy of the products is higher than the free energy of the reactants.

The reduction potential chart for metals, we can see that the most easily reduced metal in the list is Ag^+. Option C

A redox reaction is one that involves an oxidation and a reduction taking place simultaneously. This is because, the processes of electron loss and electron gain has to occur at the same time. A specie looses the electron that is gained by the other specie.

Now we know that metals are arranged in order of increasing reducing ability and decreasing reactivity. This arrangement is called the activity series of elements.

Looking at the reduction potential chart for metals, we can see that the most easily reduced metal in the list is Ag^+. Option C

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The equilibrium molarity HPO²₄- = 6.2 x 10⁻⁸M See the explanation below.

The molar concentration of a certain species in a solution is known as equilibrium molarity.

The initial concentration H₃PO₄ = 0.31 M

Kₐ₁ = 6.92 x 10⁻³ (See Image 1 attached)

Kₐ₁ = [H⁺][tex]_{eq}[/tex][H₂PO₄-][tex]_{eq}[/tex] / [H₃PO₄][tex]_{eq}[/tex]

6.92⁻³ x 10 = [(x) * (x)] / (0.31 M - x)

Solving for x, x = 0.043 M

[H+] = x = 0.043 M

[H₂PO₄-] = x = 0.043 M 0.0429805

Kₐ₂ = 6.2 x 10⁻⁸

See the second attached table

Kₐ₂ = [H+][tex]_{eq}[/tex] [HPO₄²-]eq / [H₂PO₄-]eq

6.2 x 10⁻⁸ = [(0.043 M + x) * (x)] / (0.043 M - x)

Solving for x, x = 6.2 x 10⁻⁸ M

[H₂PO₄-]eq = x = 6.2 x 10⁻⁸ M

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Answer:

OX-Y-Z

Explanation:

its the correct answer

The correct order from the most amount of motion( Kinetic energy) to the least amount of motion is Y (gas), Z (liquid), and X (ice). The correct answer is C, Y-Z-X.

In the given sequence, the states of matter with the most amount of motion (kinetic energy) to the least amount of motion are as follows:

Y - Gas (highest kinetic energy, molecules move freely and quickly in all directions)

Z - Liquid (intermediate kinetic energy, molecules have some freedom of movement but are more closely packed than in a gas)

X - Ice (lowest kinetic energy, molecules are tightly packed and have minimal movement, as it is in a solid state)

This sequence reflects the increasing freedom of movement and mobility of molecules as they transition from a solid to a liquid to a gas state.

Thus, the correct option is C.

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Answer:

correct answer is sodium

Explanation:

element is most active in this question is sodium please make me Brilliant to this correct answer

The aggregate ultimate momentum of the boy and girl must be 0 kgm/s (option C).

Conservation of momentum:

According to the principle of momentum conservation, momentum is only modified by the forces acting as they are outlined by Newton's equations of motion; momentum is never generated nor destroyed inside a problem domain.

What is Momentum?

A characteristic of a moving body that it possesses due to its mass and motion and is equal to the sum of its mass and speed.

Therefore, according to the momentum conservation law, it can be concluded that the aggregate end momentum of the boy and girl must be 0 kgm/s (option C).

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