Which element has 2 valence electrons and 5 energy levels?

There is no temperature increase during a phase change because the heat supplied to the substance is used to give the molecules in the substance energy to break free from the forces holding them together.

A phase change in a substance refers to the process by which a substance changes from one physical state to another when heat is added or removed from it.

A phase change is also called a change of state.

The various types of phase changes are as follows;

During a phase change, even though heat is entering or leaving the system, the overall temperature of the system does not change. This is because the heat energy supplied is used to overcome the forces between the molecules of the substance.

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(a) The work done when the gas expands isothermally against a constant external pressure is 87.992 kJ

(b) The work that would be done if the same expansion occurred reversibly is 167.4 J

Given that the mass of methane m is = 4.5 gram = 0.0045 kg

Volume occupies [tex]V_{1}[/tex] = [tex]12.7dm^{3}[/tex]

And volume is increased by [tex]3.3dm^{3}[/tex]

So, the increased volume [tex]V_{2}[/tex] is

12.7 + 3.3 = 16 litres

Given temperature T is 310K

Pressure is given as 210 Torr = 26664.5 Pa

(a) Now, at the given pressure the work done is given by

W = P( [tex]V_{2}[/tex] - [tex]V_{1}[/tex])

W = 26664.5 (16 - 12.7)

W = 87992.85 J

W = 87.992 kJ

(b) At reversible process work done is given by

W = nRT㏑[tex]\frac{V2}{V1}[/tex]

We have the given mass = 4.5 gram

Molar mass of methane = 16

So number of moles is

n = Mass in gram / Molar Mass

n = 4.5 / 16

n = 0.28125

So, work done is

W = 0.28125 × 8.314 × nRT㏑[tex]\frac{16}{12.7}[/tex]

W = 167.4 J

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Because boiling point is independent of liquid volume, the boiling point would not vary.

What is boiling point  ?

A liquid's boiling point changes depending on the pressure being applied; the normal boiling point is the temperature at which the vapor pressure is equal to the average atmospheric pressure at sea level (760 mm [29.92 inches] of mercury). Water boils at sea level at 100° C.

The temperature at which a liquid's vapor pressure equals the pressure around it and the liquid turns into a vapor is known as the boiling point of a substance

A liquid's boiling point varies depending on the atmospheric pressure in the area. The boiling point of a liquid is lower in a partial vacuum than it is at atmospheric pressure. A liquid's boiling point is lower under low pressure than it is under air pressure. As a result, water boils at 99.97 °C (211.95 °F) at sea level but at 93.4 °C (200.1 °F) at 1,905 m (6,250 ft) altitude under standard pressure. Various liquids will boil at different temperatures at a given pressure.

Because boiling point is independent of liquid volume, the boiling point would not vary.

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Chemistry =>Introduction to Chemistry => Scientific Method

A scientific method corresponds to a methodology to obtain new knowledge.

We must start from an idea, an assumption of how a compound or a process behaves, this is our hypothesis.

Following this, we must identify what can affect our process, what are the variables, and what will be the response variable, for this we carry out an experiment.

Once the experiments have been carried out, we must analyze the results, draw conclusions as to why the behavior occurs, and if our hypothesis is true or not.

It is useless for us to obtain new knowledge if we do not share it, We have to share the results, in this way other people can start from that knowledge to create another,

Therefore, the answer will be:

1. Make a hypothesis

2. Conduct an experiment

3. Analyze the experiment data

4. Communicate the results

Answer:Many of the physical properties of solutions differ significantly from those of the pure substances discussed in earlier chapters, and these differences have important consequences. For example, the limited temperature range of liquid water (0°C–100°C) severely limits its use. Aqueous solutions have both a lower freezing point and a higher boiling point than pure water. Probably one of the most familiar applications of this phenomenon is the addition of ethylene glycol (“antifreeze”) to the water in an automobile radiator.

Explanation:

Answer

AlBr₃ is the limiting reactant

Explanation

Mass of AlBr₃ = 23.45 g

Mole of AlBr₃ = Mass/molar mass = 23.46 g/266.69 g/mol = 0.08797 mol

Mass of Na₂O = 34.57 g

So mole of Na₂O = mass/molar mass = 34.57 g/61.9789 g/mol = 0.5578 mol

Mole ratio of AlBr₃ to Na₂O = (0.08797/0.08797) : (0.05578/0.08797) = 1:6

To know the limiting reactant, write a chemical equation for the reaction and compare the reactant mole ratio in the equation with the mole ratio above.

2AlBr₃ + 3 Na₂O -----> Al₂O₃ + 6NaBr

Mole ratio in the equation = 2:3

Comparing the mole ratio, AlBr₃ will be the first to be completely consumed.

Therefore, AlBr₃ is the limiting reactant

Answer:

a buffalo

Explanation: if its north America it needs to be native from here none of the other are from north America

The mole fraction of water decreases because, at this starting mole fraction, solid water forms before solid acetic acid.

What is mole fraction ?

Mole fraction represents the number of molecules of a particular component in a mixture divided by the total number of moles in the given mixture. It’s a way of expressing the concentration of a solution.

The amount fraction is another name for the mole fraction.  It is the same as number fraction, which is calculated by dividing the number of molecules in a constituent (Ni) by the sum of all molecules. Instead of using a Roman x, the lowercase Greek letter chi is occasionally used to represent the mole fraction. The IUPAC recommends the letter y for gas mixtures.

Because it does not include the name of the unit mole, the National Institute of Standards and Technology of the United States prefers the phrase amount-of-substance fraction to mole fraction.

Molar concentration is a proportion of moles to volume, whereas mole fraction is a ratio of moles to moles.

The mole fraction of water decreases because, at this starting mole fraction, solid water forms before solid acetic acid.

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Answer:

physical change

Explanation:

melting is a physical change, a physical change does not involve a change in chemical bonds.

Using the distribution coefficient, we can calculate the masses removed from water: a) 45.8 g; b) 48.8 g.

If the distribution coefficient between DCM (methylene chloride) and water is 11, that means that the concentration in DCM is 11 times greater than the concentration in water.

a) When equal volumes of the solvents are used, the amount of the solute in DCM (A) will be 11 times greater than the amount of solute remaining in water (B).

A + B = 50.0 g

A = 11 B

11 B + B = 50.0 g

12 B = 50.0 g

B = 50.0 g / 12

B = 4.17 g

A = 11 * 4.2 g

A = 45.8 g

b) Because the solvent volumes are not the same, we have to use concentrations. We can still label the mass of Y in DCM as A, and the mass of Y in water as B. After a single extraction with 125 mL of DCM we get:

A₁ + B₁ = 50.0 g

(A₁ / 125 mL) / (B₁ / 250 mL) = 11

2 A₁ / B₁ = 11

A₁ = 11 B₁ / 2

A₁ = 5.5 B₁

5.5 B₁ + B₁ = 50.0 g

6.5 B₁ = 50.0 g

B₁ = 50.0 g / 6.5

B₁ = 7.7 g

So, after the first extraction, 7.7 g of Y has remained in water. That means that for the second extraction:

A₂ + B₂ = 7.7 g

A₂= 5.5 B₂

5.5 B₂ + B₂ = 7.7 g

6.5 B₂ = 7.7 g

B₁ = 7.7 g / 6.5

B₁ = 1.2 g

After the second extraction, only 1.2 g of Y has remained in water, while 50.0 g - 1.2 g = 48.8 g of Y was removed from water.

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4Al + 2Pb(No3)2 → 4Al(No3) + Pb2

Hope this helps!

Answer:

Explanation:

In which step of the four-stroke engine cycle does the car release CO₂, H₂O, and CO?

O C. Exhaust

A volcano has recently irrupt it and wiped out most of the wildlife will leave it on the volcano and it will create huge impact on birds in the area going to be impacted as the volcano irrupt heat will generate and it will cause increase in the temperature that will change the life style of the various birds living in that area.

Volcano is defined as a rupture in the part of the crust of the planetary mass of the object generally Earth, which allows the hot lava as well as ash, including the gases that has been escaped from the chamber of the magma.

Therefore, A volcano has recently irrupt it and wiped out most of the wildlife will leave it on the volcano and it will create huge impact on birds in the area going to be impacted as the volcano irrupt heat will generate and it will cause increase in the temperature that will change the life style of the various birds living in that area.

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The rate of the reaction if the concentration of ethanol was doubled will remain the same.

The rate of the reaction tert-butyl ethyl ether, (ch3)3coch2ch3, in acidic conditions, will undergo the SN1 mechanism so the rate of reaction will remain the same.

The rate of reaction is the rate at which a chemical reaction takes region, defined as proportional to the increase inside the concentration of a product in step with unit time and to the lower within the awareness of a reactant in line with unit time. response prices can vary dramatically.

The speed with which a reaction takes area is called the fee of a response. as instance, timber combustion has a high response rate since the manner is fast, and rusting of iron has a low response rate as the technique is slow. Rate is most customarily calculated by the usage of the equation The devices of rate calculated in this manner are s -1.

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Electrons from fadh2 are transferred to succinate reductase and then to a small organic molecule called Ubiquinone.

Electron Transport chain?

The electron transport chain main job is to produce an electrochemical gradient. It propels the production of ATP during photosynthesis and cellular respiration in mitochondria and chloroplasts, respectively. Cellular respiration uses it.

Ubiquinone transfer electrons to Complex III from Complexes I and II as well as from other mitochondrial dehydrogenases by acting as an electron transporter in the mitochondrial respiratory chain.

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When a hydrogen atom is covalently bonded to either oxygen, , or fluorine there will be an attraction between that hydrogen and a lone pair of on a nitrogen, oxygen, or fluorine atom on an adjacent molecule. This attraction is called a bond nitrogen lone bond.

Strong intermolecular interactions known as hydrogen bonds can develop between adjacent molecules. Between the covalently bound hydrogen atom of one molecule and the electron lone pair of a second molecule, hydrogen bonds are created.

Due to their strong electronegativity, only nitrogen, oxygen, or fluorine atoms may be used in this process. These three atoms have extremely high electronegativity, which makes it simple for them to draw the electron from the hydrogen atom and establish hydrogen bonds.

Atoms within a molecule are held together by intramolecular forces. There are forces between molecules known as intermolecular forces.

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To be considered a true hydrate, a compound must follow a few rules, and one of these rules is the color being the same before and after heating. In this case we have a difference in the color, the residue after heating when dissolved in water is forming a yellow brown solution, and in the meanwhile, a colorless solution is formed when a sample of the original compound is dissolved in water, which is not a characteristic of a true hydrate.

Answer:

67 electrons

Explanation:

Most of the time, the number of protons is the same as the number of electrons because of their relation.

The mass of the object obtained is 1.32 g and the percent yield is  34.3%.

We know that the reaction equation shows the way the reactants are able to interact so as to obtain the products. We have that;

Number of moles of sodium sulfate = 0.196 M  * 57.9/1000 L

= 0.011 moles

Number of moles of magnesium chloride = 0.398 M * 167/1000 L

= 0.066 moles

Given that the reaction is 1:1, the limiting reactant is sodium sulfate

Then;

Mass of the magnesium sulfate produced = 0.011 moles * 120 g/mol

= 1.32 g

The percent yield of the magnesium sulfate = 0.453 g/ 1.32 g * 100/1

= 34.3%

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Answer:

Cyclone Movement

Explanation:

To form a cyclone, warm, moist air over the ocean rises upward from near the surface. As this air moves up and away from the ocean surface, it leaves is less air near the surface.

So basically as the warm air rises, it causes an area of lower air pressure below.

If we assume that helium acts as an ideal gas, we can calculate that 1.000 mol of it will take up 3.43 L, which is 6.53 times less than its volume at standard conditions.

Assuming that helium behaves like an ideal gas in both cases, we can calculate the volume at 2.20 K using the ideal gas equation:

PV = nRT

P - the pressure exerted by the gas (0.05256 atm)

V - the volume of the gas

n - number of moles of the gas (1.000 mol)

R - universal gas constant (0.08206 L*atm/K*mol)

T - temperature (2.20 K)

If we rearrange the equation, we get:

V = nRT/P

Now we plug in the known values:

V = 1.000 mol * 0.08206 L*atm/K*mol * 2.20 K / 0.05256 atm

V = 3.43 L

At standard conditions (273 K, 1 atm), 1 mol of an ideal gas has a volume of 22.4 L, so the volume at described conditions is 22.4 L / 3.43 L = 6.53 times smaller than at standard conditions.

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The atomic mass of element x is 85.56 amu if 72% of the atoms have a mass of 85 amu and 28% of the atoms have a mass of 87 amu

The atomic mass of an element can be determined by first multiplying the percentage of its isotopes by their atomic mass and then adding the resultants together.

As 72% of the atoms have a mass of 85 amu and 28% have a mass of 87 amu, therefore

atomic mass of element x = (72% × 85) + (28% × 87)

atomic mass of element x = (72/100 × 85) + (28/100 × 87)

atomic mass of element x = (0.72 × 85) + (0.28 × 87)

atomic mass of element x = 61.2 + 24.36

atomic mass of element x = 85.56 amu

Therefore the atomic mass of element x is calculated to be 85.56 amu.

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Bread grows mold more quickly at room temperature than in the refrigerator because more reactants will have the energy necessary to proceed to products at room temperature than at refrigerator temperatures.

Molds are formed on bread due to various reactions that facilitate the living of the molds on the bread and allow them to reproduce on the bread.

However, as molds are living organisms characterized as fungi, they need enzymes for function.

The enzymes and proteins normally function best at room temperature. On the other hand, when the temperatures are low, such as that of a refrigerator the molds will not have enough energy because the proteins and enzymes will be inactivated. Hence, molds grow on bread quickly at room temperature as compared to bread in a refrigerator.

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Water molecules slide around each other, results in making and breaking of hydrogen bonds. As energy is added, molecules move rapidly that they spread in all directions. This phase-change process is called vaporization.

The temperature of liquid water increases as it is heated up until it reaches 100°C. Water that was in  liquid state turns into vapors at this point. This  transition of a liquid into a gas is referred to as Vaporization. The water molecules absorb heat energy. As a result, the particles move more quickly as they gain extra energy until they possess sufficient energy to break free of the liquid molecules to vapors. There are two types of vaporization. 1. Boiling that occurs below the surface of a liquid. The boiling point of a liquid is the temperature at which it begins to boil. Water has a boiling point of 100 °C. 2. Evaporation that take place at the surface of the liquid. Some of the molecules that move  faster are able to overcome the forces of attraction of other molecules and escape from the water's surface.

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In order to remedy this potentially hazardous situation of Hydrochloric acid option b.  put some sodium bicarbonate on the gloves so they can be neutralized.

Hydrochloric acid, additionally known as muriatic acid, is an aqueous answer of hydrogen chloride. it's far a drab answer with a distinctively smelly odor. it's far categorized as a robust acid. It is a part of gastric acid in the digestive structures of maximum animal species, which include human beings.

Hydrochloric acid (HCl) is generally used for the neutralization of alkaline marketers, as a bleaching agent, in the food, textile, metallic, and rubber industries. it's far neutralized if launched into the soil and it rapidly hydrolyzes while exposed to water.

Hydrochloric acid is a clean, toxic liquid. it is a caustic chemical and notably corrosive, which means it right away reasons severe damage to tissues, such as burning, on touch. this text discusses poisoning from swallowing or breathing in hydrochloric acid.

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Disclaimer:- your question is incomplete, please see below for the complete question.

The hydrochloric acid utilized in this experiment can often discolor gloves if it is spilled on them during use. If this does occur, what should be done in order to remedy this potentially hazardous situation?

a. Gloves are not needed in this experiment, this question is invalid.

b. put some sodium bicarbonate on the gloves so they can be neutralized.

c. Remove the glove and wash your hand prior to putting a new pair on.

d. wash the gloves off and continue to use them.

The volume at which the pH can be used to determine the pKa of the acid is 7.40 ml if the equivalence point occurred at 14.81 ml of added sodium hydroxide.

The weak acid and the conjugate base will have an equal number of moles at the half-equivalence point as the number of moles of sodium hydroxide will neutralize half of the number of moles of the weak acid which will then produce more conjugate base.

The chemical reaction can be given as;

HA = (H^+) + A^-

Calculation of pKa:

pH = pKa + log[A^-]/[HA]

At half equivalence point, pH = pKa

As, ka = 10^-pka

Therefore, ka = 10^-pH

Volume is given which is 14.81 ml. Therefore, the volume that is used to determine the pKa of the acid can be calculated as follows;

14.81/2 = 7.40 ml

Therefore the volume used to determine the pKa of the acid is calculated to be 7.40 ml

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Based on freezing point depression, the solution that has the lowest freezing point is 30g of KBr dissolved in 100g of water; option B.

Freezing point depression is a phenomenon that occurs when a solute is dissolved in a pure solvent such as water.

When a solute is dissolved in a solvent, the freezing point depression is calculated using the formula below:

Where;

i = number of moles of ions produced

K = mola freezing point depression constant

m = molality

From the data given, i (same salt, KBr) and k are both constants.

Hence, the freezing point depression depends on the molality of the solution.

molality = moles / mass of solvent in Kg

Assuming moles = mass (since salt is the same)

Molality of A = 40 / 0.2 = 200 molal

Molality of B = 30 / 0.1 = 300 molal

Molality of A = 20 / 0.25 = 80 molal

Molality of A = 10 / 0.1 = 100 molal

Hence, solution B will have the highest freezing point depression.

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The molarity of the bromide ion is 0.882 M .

Molar concentration is a measure of the attention of a chemical species, specially of a solute in an answer, in phrases of amount of substance in keeping with unit quantity of solution.

In chemistry, the maximum typically used unit for molarity is the number of moles consistent with liter, Molarity refers to the attention of a compound or ion in a solution, and normality refers back to the molar attention handiest of the acid aspect or handiest of the base component of the solution. therefore, normality gives know-how of the solution's concentration in acid-base reactions.

Pb⁺² + 2Br⁻ => PbBr₂

19.38 ml × 0.5690 M = 11.03 millimoles of Pb⁺²

millimoles of Br⁻  = 2 × millimoles of Pb⁺²

                           = 2 × 11.03

                           = 22.06 millimoles of Br⁻

= 22.06 millimoles/25 ml

molarity = 0.882 M in Br⁻.

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Mg2N3  compound having general formula X2Y2  it having cation as +3 charge and bonds ionically with group 15 in a 2:3 ratio.

When two or more elements combine chemically  in a specific mass ratio, the resulting product is called a compound. Compounds can be defined as substances consisting of two or more different types of elements in a fixed ratio of their atoms.

A compound is one where  different types of atoms have joined together to form molecules. For example, water is a compound. The chemical name of water is H2O because it contains two hydrogen atoms and one oxygen atom chemically bonded together.

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