Assuming constant pressure, rank these reactions from most energy released by the system to most energy absorbed by the system, based on the following descriptions:__________.
A: Surroundings get colder and the system decreases in volume.
B: Surroundings get hotter and the system expands in volume.
C: Surroundings get hotter and the system decreases in volume.
D: Surroundings get hotter and the system does not change in volume.

Answer:

The system can operate on a set level of parts per million (ppm) chlorine, where the set level is automatically maintained.

A redox reaction is a chemical reaction in which one or more of the reacting species undergoes oxidation and one or more undergoes reduction. An oxidizing agent is an element or compound that oxidizes another substance, while a reducing agent is an element or compound that reduces another substance.

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Rhenium (Re) has two stable isotopes, 185Re and 187Re. The average atomic mass of Rhenium is 186.2 amu.

The mole percent of 185Re in Rhenium can be calculated as follows:

Mole percent of 185Re = (number of moles of 185Re/total number of moles of Rhenium) × 100

To find the number of moles of 185Re, we need to know the fractional abundance of 185Re, which can be calculated as follows:

Fractional abundance of 185Re = mass percent of 185Re/atomic mass of Rhenium

Fractional abundance of 185Re = (185/186.2) × 100 = 99.35%

The mass percent of 185Re is 185 because it is the mass number of the isotope that we are interested in.

Since the atomic mass of Rhenium is the weighted average of the masses of the two isotopes,

we can assume that the mass percent of 187Re is (100 - 99.35) = 0.65%.

Now we can find the number of moles of each isotope in 100 g of Rhenium.

Number of moles of 185Re = (0.9935 × 100 g)/185 g mol⁻¹ = 0.53649 mol

Number of moles of 187Re = (0.0065 × 100 g)/187 g mol⁻¹ = 0.00034 mol

Total number of moles of Rhenium = 0.53649 + 0.00034 = 0.53683 mol

Therefore, the mole percent of 185Re in Rhenium is:(0.53649/0.53683) × 100 = 99.94% ≈ 100%

So the answer is: (b) 50%.

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Answer:

m = 19 grams

Explanation:

Given that,

No. of moles, n = 0.8

The molar mass of magnesium, M = 24.305 u

We need to find the mass of 0.80 moles of Mg. We know that given mass to the molar mass is equal to no of moles. Let the mass is m. So,

\(n=\dfrac{m}{M}\\\\m=n\times M\\\\m=0.8\times 24.305 \\\\m=19.444\ \text{grams}\)

or

m = 19 grams

So, the mass of 0.8 moles of Mg is 19 grams.

The initial concentration of acetic acid in the vinegar is 0.134 M.

Acid is a type of chemical that has a sour taste and can corrode metals and other materials.

Concentration refers to the amount of a substance in a mixture, usually expressed in terms of the amount of solute per unit of solvent.

In this context, we are trying to find the initial concentration of acetic acid in vinegar, given that acetic acid is the only acid in vinegar with a Ka of 1.8 x 10⁻⁵.

To calculate the initial concentration of acetic acid in vinegar, we can use the formula for Ka, which is the equilibrium constant for the dissociation of a weak acid:

Ka = [H3O+][A-] / [HA]

where [H3O+] is the concentration of hydronium ions, [A-] is the concentration of the conjugate base (acetate ions, in this case), and [HA] is the concentration of the weak acid (acetic acid).

Since vinegar contains only acetic acid, we can assume that the initial concentration of acetic acid ([HA]0) is equal to the initial concentration of the vinegar solution.

Let's call this concentration x. The equilibrium concentrations of [H3O+] and [A-] are both equal to the square root of Ka times [HA], or Ka^(1/2) * x.

Substituting these values into the equation for Ka, we get:

Ka = [H3O+][A-] / [HA]1.8 x 10⁻⁵ = (Ka^(1/2) * x)^2 / x

Simplifying this expression, we get:

x = Ka^(1/2) / (1.8 x 10⁻⁵) = (1.8 x 10⁻⁵)^(1/2) / (1.8 x 10⁻⁵) = 0.134 M

Therefore, the initial concentration of acetic acid in the vinegar is 0.134 M.

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Answer:

Earth

Explanation:

The Earth and the sun are the part of the solar system and the earth and other planets revolve around the Sun. The solar system is placed in the universe.

\(C6H_14\)is the molecular formula for Hexane, a hydrocarbon. The correct model for \(C6H_14\) is D. Option D is correct answer.

/\/\/\/:Hexane (\(C6H_14\)) is an alkane with a chain of six carbon atoms, having 14 hydrogen atoms. The bond angles of carbon atoms in hexane are 109.5 degrees, and carbon atoms in hexane have a tetrahedral geometry. The representation of a molecule in a model helps to visualize the 3D structure of the molecule. A simple way to represent the 3D structure of hexane is by using the wedge-and-dash notation. In this notation, solid wedges represent bonds coming out of the plane of the paper towards us, and dashed lines represent bonds going back into the plane of the paper away from us. Using this notation, the correct model of hexane (\(C6H_14\)) would be D. /\/\/\/.

The correct option is D.

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The cellular organelle that is most affected by CO poisoning is mitochondria (option B).

Mitochondria is a cellular organelle found in eukaryotic cells and responsible for the production of energy in form of ATP.

Carbon monoxide (CO) is a common environmental pollutant released when fossil fuels are burned. The major target of this pollutant is the mitochondria.

Carbon monoxide (CO) binds to cytochrome oxidase of the electron transport chain in the mitochondria, thereby, blocking oxidative phosphorylation and ATP production. As ATP declines, there is no energy to drive the breathing muscles.

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At t = 20 minutes, there is approximately 180.48lb of salt and 60gal of solution in the tank.

Let's denote A(t) as the amount of salt at time t.

The rate of change of salt in the tank is given by the rate at which brine enters the tank minus the rate at which the solution leaves the tank. In this case, the rate at which brine enters the tank is 4gal/min and contains 2lb of salt per gallon. So, the rate of salt entering the tank is (4gal/min) * (2lb/gal) = 8lb/min.

The rate at which the solution leaves the tank is 6gal/min. Since the tank initially contains 100gal of pure water, the amount of solution leaving the tank without salt is (6gal/min) * (100gal) = 600gal.

Therefore, the differential equation for the amount of salt A(t) is dA/dt = 8 - (6/100)A.

To solve this differential equation, we can use separation of variables and integrate. The solution for A(t) is A(t) = 400(1 - e^(-t/50)).

At t = 20 minutes, we can substitute t into the solution to find the amount of salt in the tank. A(20) = 400(1 - e^(-20/50)) ≈ 400(1 - 0.5488) ≈ 400(0.4512) ≈ 180.48lb.

The amount of solution in the tank at t = 20 minutes is 100gal + (4gal/min - 6gal/min)*20min = 100gal - 40gal = 60gal.

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There are 40 lb of salt in the tank at t = 20 minutes. Since the tank initially contains 100gal of pure water.

We can use the concept of differential equations. We know that the rate at which salt enters the tank is 2lb/gal * 4gal/min = 8lb/min. Similarly, the rate at which salt leaves the tank is 6gal/min.

The amount of salt and solution in the tank at t = 20 minutes, we substitute t = 20 into the equation:

A(20) = 2(20) = 40 lb.

Therefore, there are 40 lb of salt in the tank at t = 20 minutes. Since the tank initially contains 100gal of pure water.

Salt is a mineral composed primarily of sodium chloride (NaCl).

Salt is essential for life in general, and saltiness is one of the basic human tastes.

Salt is one of the oldest and most ubiquitous food seasonings, and is known to uniformly improve the taste perception of food, including otherwise unpalatable food.

Salting, brining, and pickling are also ancient and important methods of food preservation.

Salt is mostly sodium chloride (NaCl). Sea salt and mined salt may contain trace elements. Mined salt is often refined. Salt crystals are translucent and cubic in shape; they normally appear white but impurities may give them a blue or purple tinge.

When dissolved in water sodium chloride separates into Na+ and Cl− ions, and the solubility is 359 grams per litre.

From cold solutions, salt crystallises as the dihydrate NaCl·2H2O.

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Answer:

1.45 is larger for density

Answer:

Explanation:

Using Organic Compounds quick check

do you know the refining design quick check

Answer: connections academy?

Explanation: do you go there? I saw that you were answering questions and asking for help on the midterm for A&P and the same one is currently on schedule for me

The excited hydrogen atom with the electron in energy level 6 emits a photon of wavelength 94 nm when the electron drops to energy level 4.

The excited hydrogen atom emits a photon of wavelength 94 nm, which corresponds to a photon energy of 13.2 electron volts (eV) using the formula E = hc/λ, where h is Planck's constant and c is the speed of light. This photon is emitted when the electron drops from a higher energy level to a lower energy level.

To determine the energy level the electron drops to, we can use the formula for the energy of an electron in a hydrogen atom:

\(E_n = -13.6/n^2 eV\)

where n is the principal quantum number of the energy level. The excited electron is in energy level 6, so its initial energy is \(-13.6/6^2 = -0.75 eV\). When the electron drops to a lower energy level, the energy difference between the initial and final levels is equal to the energy of the emitted photon.

Using the formula \(E = E_i - E_f\), where \(E_i\) is the initial energy level and \(E_f\) is the final energy level, we can solve for \(E_f\):

\(E_f = E_i - E = -0.75 eV - 13.2 eV = -13.95 eV\)

Plugging this value into the formula for the energy of an electron in a hydrogen atom, we can solve for the principal quantum number n:

\(n^2 = 13.6/-E_fn^2 = 13.6/13.95\)

n ≈ 3.97

Since n must be a positive integer, the electron drops to the energy level with a principal quantum number of 4. Therefore, the excited hydrogen atom with the electron in energy level 6 emits a photon of wavelength 94 nm when the electron drops to energy level 4.

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Answer: Option (A) is the correct answer.

Explanation:

An atom who has seven valence electrons in its ground state will have the following electronic configuration in its sub shells as 2, 7.

Thus, there will be in total 9 electrons and it is known that fluorine has atomic number 9.

Whereas sodium has 2, 8, 1 electrons in its sub-shell.

Calcium has 2, 8, 8, 2 electrons in its sub-shell and oxygen has 2, 6 electrons in its sub-shell.

Thus, we can conclude that out of the given options, fluorine is the element whose atom in the ground state has seven valence electrons.

Option A. The processes are necessary in order to turn sand into rock is Compaction and cementation

The cycles important to transform sand into rock are compaction and cementation. Compaction happens when layers of dregs are kept on top of one another, making the grains of sand become packed and diminishing the pore space between them. Cementation happens when minerals hasten out of water and fill in the leftover pore space, restricting the grains of sand together into a strong stone. This interaction is called lithification and it is the means by which most sedimentary rocks are shaped. Without compaction and cementation, sand would stay unconsolidated and not structure into a strong stone.

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When the mole fraction of glucose in (c6h12o6) and 162 g of water is calculated, the solution is 0.10.

First, we need to calculate the total number of moles of the glucose and water.

Moles of glucose = Mass of glucose / Molar mass of glucose

Molar mass of glucose (C6H12O6) = 6*(12.01) + 12*(1.01) + 6*(16.00) = 180.16 g/mol

Moles of glucose = 180 g / 180.16 g/mol = 1 mol

Moles of water = Mass of water / Molar mass of water

Molar mass of water (H2O) = 2*(1.01) + 16.00 = 18.02 g/mol

Moles of water = 162 g / 18.02 g/mol = 9 mol

The total number of moles in the solution is the sum of the moles of glucose and water:

Total moles = 1 mol + 9 mol = 10 mol

The mole fraction of glucose can then be calculated as the ratio of the moles of glucose to the total number of moles:

Mole fraction of glucose = Moles of glucose / Total moles

Mole fraction of glucose = 1 mol / 10 mol = 0.10

The mole fraction of glucose in the given solution, containing 180 g of glucose (C6H12O6) and 162 g of water, is 0.10.

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Answer:

hyposthesis

Explanation:

The new pH of the solution after the addition of water would be 13.22.

V(total) = 609 ml + 594 ml

V(total) = 1203 ml

C = (594 ml)/(1203 ml)

C = 0.493

pOH = -log(0.493)

pOH = 0.31

New pH of the solution = 13.5292 - 0.31 = 13.22

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Answer:

aluminium is too high in the reactivity series

Explanation:

it is more reactive than carbon so electrolysis will have to be used to extract aluminium.

PEL stands for permissible exposure limit and TLV stands for threshold limit value.

These terms refer to the maximum concentration of a chemical substance that a worker can be exposed to without experiencing adverse health effects. The flash point of a chemical substance is the temperature at which it can ignite if exposed to an ignition source. It would not be a good idea to sit on a stool while working in the organic chemistry lab because stools can be unstable and could easily tip over. This could result in spills or accidents that could harm the worker or damage the equipment.
Wearing contact lenses in the laboratory may not be the best idea as chemicals could splash into the eyes and become trapped between the lens and the eye, causing irritation or injury. It is recommended that protective goggles be worn instead.

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Moles of Carbon dioxide : n = 4.037 x 10⁻³

Given

2.43 x 10²¹ molecules of Carbon dioxide

Required

Moles

Solution

1 mol = 6.02 x `10²³ particles(molcules, atoms, ions)

Can be formulated :

N = n x No

n = moles

No = Avogadro's number 6.02 x `10²³

moles of Carbondioxide :

n = N/No

n = 2.43 x 10²¹ / 6.02 x `10²³

n = 4.037 x 10⁻³

Ignoring the effects of recoil, the minimum energy must the photon have for this reaction to occur is 10 MeV

The nuclear reaction is (28,14)Si+ γ---(24,12)Si+He(2,4)

The binding energy that holds the nuclide is

E=Δmc^2

where Δm is the mass defect

Δm=27.976927+0-[23.985042+4.002602]

Δm=-0.010717x1.66054x10^-27 kg

So the minimum energy of photon should be

ΔE=Δmc^2=0.017796x10^-27x(3x10^8)^2/1.6x10^-19 V

ΔE= 10 MeV

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The specific exergy of the system is 718 kJ/kg.

Given data:

Mass of Hydrogen (H2) = 3 pounds

Temperature of Hydrogen (H2) = 70 °C

= (70+273.15)

= 343.15 K

Pressure of Hydrogen (H2) = 1.2 MPa

Dead state temperature = 20 °C = (20+273.15) = 293.15 K

Dead state pressure = 101.325 kPa

Properties of hydrogen and water:

Here, we need to calculate the specific exergy of the system by using dead state temperature and pressure.

The specific exergy is defined as the maximum work obtainable when a system is brought to the dead state.

The formula for specific exergy is given as:

Exergy = h - hds

Where,h = specific enthalpy of the system

hds = specific enthalpy of the system at the dead state

We need to first calculate the specific enthalpy of Hydrogen (H2) at 70 °C and 1.2 MPa using the following table:

Hydrogen 70°C, 120k Pa 3162 54.7 4578 11.8

Here, Specific enthalpy of Hydrogen (H2) at 70 °C and 1.2 MPa

(h) = 4578 kJ/kg

Similarly, we need to calculate the specific enthalpy of Hydrogen (H2) at dead state conditions of 20 °C and 101.325 kPa:

Hydrogen 20°C, 101.325 kPa 2650 53.13 3860 11.94

Here,

Specific enthalpy of Hydrogen (H2) at dead state conditions of 20 °C and 101.325 kPa (hds)

= 3860 kJ/kg

Therefore, the specific exergy of the system is:

Exergy = h - hds

Exergy = 4578 - 3860

Exergy = 718 kJ/kg

Therefore, the specific exergy of the system is 718 kJ/kg.

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Answer:

28g

Explanation:

Given parameters:

Number of moles of hydrogen  = 3moles

Unknown:

Mass of nitrogen used = ?

Solution:

 To solve this problem, let us establish the balanced reaction equation first;

             N₂  + 3H₂ →  2NH₃

From the balanced reaction equation;

                 3 mole of H₂ will combine with 1 mole of N₂

Now,

   Mass of Nitrogen  = number of moles x molar mass

         Molar mass of N₂  = 2(14) = 28g/mol

   Mass of Nitrogen  = 1 mole x 28g/mole  = 28g

Answer:

Isotopes

Explanation:

An isotope are the atoms of an element with similar chemical identity and number of protons but different atomic masses. This means that isotopes of an element differ from one another by their number of NEUTRONS.

For example, the uranium element possesses isotopes as follows: Uranium-235 and uranium-238. This two isotopes have the same chemical identity and number of protons/atomic no., which is 92. However, the atomic masses (235 and 238) are different.

Answer:

Isotopes

Explanation:

The balanced equation for the reaction of silver nitrate and sodium chloride is:

AgNO3(aq) + NaCl(aq) → AgCl(s) + NaNO3(aq)

In this reaction, silver nitrate and sodium chloride react to form silver chloride and sodium nitrate. Silver chloride is a precipitate, which means that it forms a solid that falls out of the solution. The sodium nitrate remains in the solution.

The equation is balanced because the number of atoms of each element is the same on both sides of the equation. There are 1 silver atom, 1 nitrogen atom, 1 oxygen atom, and 1 chlorine atom on both sides of the equation.

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The molarity of a solution is the concentration of a substance in solution, expressed as the number of moles of solute per litre of solution.

Molarity = no of moles ÷ volume

According to this question, we are given three concentrations of NaCl solution. First, we find the no of moles of each as follows:

Next, we find the mass of each mole given the molar mass of NaCl is 58.5g/mol.

Therefore, how to prepare these solutions is as described above.

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No, diatomic elements cannot exist as single atoms.

Diatomic elements are those that naturally occur as a molecule of two atoms of the same element, such as oxygen (O2), nitrogen (N2), and hydrogen (H2). These elements are chemically stable in their diatomic form and have strong covalent bonds that keep the atoms together.

It is thermodynamically unfavorable for diatomic elements to exist as single atoms, as the energy required to break the covalent bond is very high. Therefore, diatomic elements will always exist as a molecule of two atoms. This can be observed in their physical and chemical properties, which are unique to the diatomic form of the element.

Overall, diatomic elements are a unique class of elements that exist naturally as molecules of two atoms. It is not possible for them to exist as a single atom due to their strong covalent bond.

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The answer is (d) burning gasoline in a car's engine as it involves a chemical change rather than a physical change.

Physical changes involve a change in the physical state or appearance of a substance, without altering its chemical composition.

Freezing water to make ice cubes is a physical change as the water undergoes a change of state from liquid to solid without any change in its chemical composition. Tearing a piece of aluminum foil is a physical change as it changes the shape and size of the foil but does not change its chemical composition. Boiling water for soup is a physical change as it involves a change of state from liquid to gas, again without any change in the chemical composition of water. Burning gasoline in a car's engine is a chemical change as it involves the combustion of gasoline with oxygen to produce carbon dioxide, water vapor, and energy. Melting gold to make jewelry is a physical change as it involves a change in the state of the metal from solid to liquid without any change in its chemical composition.

Therefore, the answer is (d) involves a chemical change rather than a physical change.

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