A chemistry teacher mixed two clear substance together and notices a solid forming at the bottom of the beaker. Is the teacher demonstrating a physical or chemical change?

A. Chemical change because a precipitate was formed
B. Physical change because two substances were mixed together
C. Chemical change because two substances were mixed together
D. Physical change because a precipitate was formed.

Carbon electrodes are changed frequently in electrolysis as the carbon in the carbon electrodes burns to give out Carbon-di-oxide.

Carbon electrodes are used in electrolysis to facilitate the transfer of electrons between the anode and the cathode. The carbon electrode is usually in the form of a rod or plate and is electrically connected to the anode.

The carbon electrode may also be used to help reduce the overall resistance of the electrolytic cell.

Carbon electrodes are used in electrolysis because they are chemically inert and have a high electrical conductivity.

However, carbon electrodes must be changed frequently because they become corroded and lose their electrical conductivity over time.

This is because carbon burns out in the Carbon electrodes to give out Carbon-di-oxide. That is why the carbon anodes should be changed frequently.

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The subgame perfect Nash equilibrium is to hold elections to pursue the moderate policy.

A perfect Nash equilibrium for a subgame is usually derived from the game's various final outcomes by backward induction eliminating branches where each player makes incredible moves from that node. The main difference between subgame perfect equilibrium and Nash equilibrium is that subgame perfect equilibrium requires all threats to be reliable.

Therefore, the study of the perfect balance of subgames is a reliable threat study. Subgame perfect equilibria are a subset of Nash equilibria. A Nash equilibrium of an extended game is a subgame perfect equilibrium if every subgame induces a Nash equilibrium game. A Nash equilibrium in which no part of the player's strategy contains incredible threats or promises is called a complete subgame.

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To solve the stoichiometry problems we need the amount of reactants given in mole and the product is sought in mole. We use  it because then all we have to do is the mole ratio from the balanced chemical equation  to solve the problem

The option B is correct.

What do you mean by Stoichiometry ?

Stoichiometry can be defined as  the quantitative relationships or ratios between two or more substances undergoing a physical change or chemical change. Jeremias Benjaim Richter defined stoichiometry in 1792 as the science of measuring quantities or mass ratios of chemical elements. It is the study of mass relations

It can be analyzed by

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A region of a polypeptide that folds in a particular way, relatively independently of the rest of the molecule, is a folding domain.

Thus, the correct option is E.

Domains as known tertiаry structures are the folding of the secondаry structure into distinct аrrаngements. The tertiаry structure of а protein describes the mаnner in which the secondаry structurаl elements аre аrrаnged in three dimensions to creаte а stаble moleculаr entity. In mаny cаses, it is convenient to describe а protein in terms of regions of the polypeptide chаin thаt might fold аutonomously. These regions аre cаlled domаins аnd much of the discussion of tertiаry structure centres on the clаssificаtion of these units of protein structure.

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Answer: (0.800g BaCl2) / (208.233g BaCl2/mol) =

0.00384 mol BaCl2

Explanation: Hope this helps :)

The number of moles of anhydrous barium chloride is equal to 3.84 ×10⁻³ mol and the number of moles of water is equal to 7.78 ×10⁻³ mol.

A mole can be described as a standard unit that is used to determine the number of atoms, molecules, ions, or other particular particles in the given mass of the substance. The mass of one mole of any chemical element is known as atomic mass and that of any chemical compound is called the molar mass of that compound.

Given the chemical reaction of decomposition of barium chloride:

[tex]BaCl_2.2H_2O\longrightarrow BaCl_2 +2H_2O[/tex]

Given the mass of the hydrated barium chloride = 0.940 g

The mass of the anhydrous  barium chloride = 0.800 g

The molar mass of the anhydrous barium chloride = 208.23 g/mol

The number of moles (n) of anhydrous barium chloride = 0.800/208.23

n = 3.84 ×10⁻³ mol

The mass of the water = Mass of hydrated barium chloride - anhydrous barium chloride

Mass of water = 0.940 -0.800 = 0.14 g

The number of moles of water = 0.14/18 = 7.78 ×10⁻³ mol

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Answer:

4

Explanation:

Having the coefficient 4 in front of HCl and the coefficient 2 in front of H₂O balances out the equation.

The product formed in the Diels-Alder reaction is given below. It is a (4+2) addition and a cis-product is formed.

Two organizations in a molecule can be distinctive and, if changed, generate compounds that are stereoisomers. A magnetic interaction arises among two debris such as hydrogen nuclei with non-0 spin. when two enantiomers have exclusive charges of reaction. A not-unusual instance of a pair of enantiomers is dextro lactic acid and laevo lactic acid.

The definition of a stereoisomer is any of a group of isomers wherein atoms are linked inside the identical order but fluctuate in their spatial association. In stereoisomerism, the atoms making up the isomers are joined up inside the identical order, but nevertheless, control to have an exceptional spatial arrangement. Geometric isomerism is one form of stereoisomerism. these isomers arise when you have confined rotation someplace in a molecule.

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Student 1 states that the molecules that are larger in size and are more attracted to the solvent will move further along the TLC plate employing the correct specific reasoning.

Why do some substances move further up the TLC plate than others?

Larger molecules take longer to move up the chromatography paper or TLC plate, whereas smaller molecules are more mobile. Likewise, the polarity of the molecules can affect how far the spots travel, depending on the type of solvent used.

What factor determines which molecules travel further in chromatography?

The stronger a compound is bound to the adsorbent, the slower it moves up the TLC plate. Non-polar compounds move up the plate most rapidly (higher Rf value), whereas polar substances travel up the TLC plate slowly or not at all (lower Rf value).

Thus, the molecules larger in size are more attracted to solvent will move further along the TLC plate is the reason why molecules move further than others in a chromatogram. So, student 1 is the correct option.

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Isotopes of elements having atomic number less than 20 and with a neutron to proton ratio of close to 1 are more likely to be stable.

What is an isotope?

Isotopes are two or more atom kinds that share the same atomic number (protons in the nucleus), placement in the periodic table, and chemical element but have distinct nucleon numbers (mass numbers) as a result of possessing a different quantities of neutrons in their nuclei. Although the chemical properties of each isotope of a given element are nearly identical, they differ in their atomic weights and physical characteristics. The atomic number of an atom is the sum of the number of protons in the nucleus and the number of electrons in a neutral (non-ionized) atom. The mass number of an atom is determined by the quantity of nucleons—both protons and neutrons—in its nucleus, and it varies for each isotope of a given element.

Isotopes of elements having atomic number less than 20 and with a neutron to proton ratio of close to 1 are more likely to be stable.

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Molecular Weight - The grams of solute that are needed is 3.5 g.

What is molecular weight?

The mass of the a given molecule is its molecular mass (m), which is expressed in daltons. Because they contain various isotopes of an element, different molecules of same compound can have distinct molecular masses. According to IUPAC, the related quantity comparative molecular weight is a unitless comparison between the mass of a molecule and the truly united atomic mass unit (also called the dalton).

GIVEN:

c =  Molarity = 0.1 M

M = Molar mass = 350 g/mol

V = Volume of solution = 100 mL = 0.1 L

n = Number of moles

m = Mass of solute

C = n/v

n =0.01 moles

M=m/n

m= 3.5g

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Answer: Photon

Explanation:

The electron can reach its ground state level either with one direct jump or with shorter jumps via intermediate levels. If an excited electron emits a photon, the energy hf of that photon equals the energy difference between the initial energy level of the electron and a lower level.

Taking into account definition of percent yield, the percent yield of the reaction is 62.78%.

In first place, the balanced reaction is:

SiO₂(s) + 3 C(s) = SiC(s) + 2 CO(g)

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:

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

The limiting reagent is one that is consumed first in its entirety, determining the amount of product in the reaction.

To determine the limiting reagent, it is possible to use a simple rule of three as follows: if by stoichiometry 44 grams of SiO₂ reacts with 36 grams of C, 50 grams of SiO₂ reacts with how much mass of C?

mass of C= (50 grams of SiO₂×36 grams of C)÷ 44 grams of SiO₂

mass of C= 40.91 grams

But 40.91 grams of C are not available, 40 grams are available. Since you have less mass than you need to react with 50 grams of SiO₂, C will be the limiting reagent.

The percent yield is the ratio of the actual return to the theoretical return expressed as a percentage.

The percent yield is calculated as the experimental yield divided by the theoretical yield multiplied by 100%:

percent yield= (actual yield÷ theoretical yield)× 100%

where the theoretical yield is the amount of product acquired through the complete conversion of all reagents in the final product, that is, it is the maximum amount of product that could be formed from the given amounts of reagents.

Considering the limiting reagent, the following rule of three can be applied: if by reaction stoichiometry 36 grams of C form 40 grams of SiC, 40 grams of C form how much mass of SiC?

mass of SiC= (40 grams of C×40 grams of SiC) ÷36 grams of C

mass of SiC= 44.44 grams

The theoretical yield of SiC is 44.44 grams.

In this case, you know:

Replacing in the definition of percent yield:

percent yield= (27.9 grams÷ 44.44 grams)× 100%

Solving:

percent yield= 62.78%

Finally, the percent yield is 62.78%.

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If the pressure of a gas is tripled and the absolute temperature of the gas is quadrupled then volume of the gas change is 4/3

Volume is the space occupied within the boundaries of an object in three dimensional space

Here the relationship between pressure volume and temprature can be expressed as

PV/T

And then

P₁V₁/T₁ = P₂V₂/T₂

So in this case P₁V₁T₁ are equal to 1 and have the pressure triple so that P₂ = 3 and the temprature quadrupled so that T₂ = 4 and then we have to calculate V₂ = ?

(1)(1)/1 = (3)V₂  /4

1 = 3/4 V₂

1(4/3) = (3/4) V₂ 4/3

V₂ = 4/3

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Answer:

the correct answer is 5

Explanation:

i just know

The molarity when a student dissolves of resveratrol in of a solvent with a density of . the student notices that the volume of the solvent does not change when the resveratrol dissolves in it is 0.185 M and 0.3645 g

As we know the formula of Resveratrol

C14H12O3

We know the molar mass is 228 g/mol

Mole of resveratol is 19/228=0.083 g

So, the molarity of the Solution is 0.083/0.45=0.185 L

Now as we know molality mole of the solute mass of solvent

volume of solvent = 450 ml

Molality is the mass of solute upon the mass of solvent

M=0.81X450=0.3645 kg

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The penny must have changed its color because an oxidation reaction. When we heat some metals, the trnasform into oxides, for exxample Zinc oxide ZnO or CuO.

Moreover, his compounds are colored molecules mostly brown or black colored compounds. First at all when we put the pennies into a acetic acid solution, a redox reaction wiil happen. The acetate is an oxidant  and it will react with the Cu, Zn and Sn to reduce them. for example, if we have ZnSO4 in the plate and it will be heated, the Zn will suffer a redox reaction and will form Zn0. a metalic form. that´s why the color changes.

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The relationship between process capability index, Cp and process capability ratio, Cr is given as Cp = 1/Cr.

In statistics, process capability index is used to measure the variations or changes that occur in a process.

In general, the it lies between the specification limits which are also held in check while performing the Process capability index.

As we know that different processes has different optimal situations which help us to contrast the processes and also help us to identify if the obtained results meet our expectations.

Simply put, Process capability index also called process capability ratio is a statistical measurement method to identify the possible variations in a process.

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Organic molecules form covalent bonds and inorganic compounds form ionic bonds.

The main interaction in ionic compounds is ionic bonding, a type of chemical bonding that involves the electrostatic attraction between two atoms or ions with dramatically different electronegativities.

A chemical link known as a covalent bond includes the sharing of electrons between atoms to generate electron pairs. Covalent bonding is the stable equilibrium of the forces of attraction and repulsion between atoms when they share electrons.

Inorganic compounds have ionic bonds. There is always an ion-dipole attraction when inorganic compounds are combined with water, meaning the ions are solvated (hydrated)

Covalent bonding is frequently seen in molecules containing carbon, usually known as organic compounds. The two atoms' common pair of electrons has now extended around their nucleus, resulting in the formation of a molecule.

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The coffee's pH will be 10.

What does pH refer to?

because hydrogen ions attach to water molecules for form hydronium ions.

To calculate the pH of a solution, use the equation

pH = − log [H3O+]

Since we are given the hydronium ion (H3O+) concentration of the solution, we can plug this value into the formula.

pH = −log[ 1.00 × 10^−10M]

pH = 10

Hence, The pH of this solution is 10

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61.62 g of precipitate of AgCl is formed after the reaction is complete

As we know the formula :

M = n / V

where

M = Molarity

n= no of moles

V = volume ( in litres)

Concentration of NaCl = 1.527 M = 1.527 mol/L

Volume of NaCl solution = 97.19 ml = 97.19 /1000

= 0.09719 L

Number of moles of NaCl

= 1.527 mol/L × 0.09719 L

= 0.148 mol

Concentration of Ag2SO4 = 1.923M = 1.923 mol/L

Volume of Ag2SO4 solution = 111.84 ml = 111.84/1000

= 0.11184 L

Number of moles of Ag2SO4

= 1.923 mol/L × 0.11184 L

= 0.215 mol

Balanced equation:

Ag2SO4 (aq) + 2 NaCl (aq) -->2 AgCl (s) [precipitate] + Na2SO4 (aq)

1 mol of Ag2SO4 reacts with 2 moles of NaCl produces 2 moles of AgCl,

then 0.215 mols of Ag2SO4 will react with 2 × 0.215 moles = 0.43 moles of NaCl will produce 0.43 moles of AgCl

Molar mass of AgCl = 143.32 g/mol

Mass of precipitate formed = no of moles× molar mass

= 0.43 mol × 143.32 g/mol = 61.62 g

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Based on the number of atoms in 1 mole of a substance, the number of atoms in 1 mole of  K₂ZnO₂ is 3.01 * 10²⁴ atoms.

Atoms are the smallest particle of an element that can exist and still retain the properties of that element.

Atoms of elements take part in chemical reactions.

The number of atoms in a mole of a substance is equal to 6.03 * 10²³.

In 1 mole of the compound K₂ZnO₂:

there are 2 moles of K atoms = 6.03 * 10²³ * 2 atoms

there are 1 mole of Zn atoms =6.03 * 10²³ atoms

There are 2 moles of O atoms = 6.03 * 10²³ * 2 atoms

Total number of atoms in 1 mole of  K₂ZnO₂ = 3.01 * 10²⁴ atoms.

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The following were the goals of reconstruction is to reincorporate the south into the union, to establish the equality under law for African Americans, and to assist the African Americans in the transition from slavery to freedom.

In the reconstruction the period includes civil war and the southern states defeated confederation. reconstruction was basically period of political crisis . The major drawback is that the African American never be equal on economic equality with the whites.

Thus, The following were the goals of reconstruction is to reincorporate the south into the union, to establish the equality under law for African Americans, and to assist the African Americans in the transition from slavery to freedom.

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The anion name for telluric acid is TeO₃²⁻ is tellurite ion

Anion are ion that are negatively charged and ion are charged atom or molecule and if a balanced atom loses one or more electron and it will become positively charged cation and if balanced atom gain one or more electron it will become  negatively charged anion and in the telluric acid means H₆O₆Te and the anion are formed TeO₃²⁻ is called as tellurite ion and telluric acid as tellurium source in the synthesis of oxidation catalyst

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The lowest-energy distribution of electrons in the sublevels for an atom of a particular element is called the ground state.

When an atom, molecule, or ion and its electrons are at their lowest potential energy level, they are said to be in the ground state. They are said to be thrilled if their energy level is higher. Excited electrons are those with energies greater than their ground state. When many quantum mechanical states are present at the same energy, these levels are known as degenerate energy levels.

An electron orbit around an atom's nucleus is referred to as an electron shell or energy level in chemistry. This atomic model by Bohr states that the electrons follow a circular path around the nucleus known as an orbit.

The "K shell" is the shell that is closest to the nucleus; it is followed by the "L shell," the "M shell," and so forth as one moves farther from the nucleus. Quantum numbers (n = 1, 2, 3, 4, etc.) or alphabets (K, L, M,...) can be used to represent the shells.

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The required heat in this case id 68J

Aluminum is an element with the atomic symbol Al, and the atomic number of this element is 13 in the periodic table. Aluminum is weaker than steel, and also it is less dense than steel.

specific heat, is the quantity of heat required to raise the temperature of one gram of a substance by one  degree celsius. The units of specific heat are usually calories or joules per gram per Celsius degree.

When there is change of heat the expression used will be;

Q = mCΔT

Where m = 5 grams, ΔT = 37[tex]^oC[/tex] - 22[tex]^oC[/tex] ⇒ 15[tex]^oC[/tex], C = 0.900J

Q = 5 × 0.900 × 15

= 68 J

Therefore the required heat in this case is 68J

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Answer:

a producer is an organisms that produce food for themselves and other organisms.

6.9×10^23 molecules of oxygen are produced when 43g of h2o decompose.

2H20⇆O2+2H2

given mass,H2O=43 g

molar mass H2O=18 g

moles=given mass/molar mass

moles=43/18

moles=2.3 mol

molecules of oxygen= 2.3/2=1.15 mol

molecules of oxygen=1.15 mol×6.022×10^23

molecules of oxygen=6.9×10^23 molecules.

The non-metallic chemical element oxygen is found in Group 16 of the periodic table, generally known as the oxygen group (O). All living creatures require the colorless, tasteless, and odorless gas known as oxygen. When plants use it as a source of carbon and release the oxygen back into the environment, plants utilise the carbon dioxide that animals have taken up and converted it into.

Oxygen may react with almost every other element to form compounds in addition to reactions that remove elements from their combinations with one another. Combustions are the name for these reactions, which are typically accompanied by the creation of heat and light. The most important component is water.

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Heat is the flow of energy caused by a temperature difference

Heat is the energy that is transferred from one body to another as the result of a difference in temprature and if two bodies at different temprature are brought together energy is transferred that is heat flow from the hotter body to the colder and heat is the transfer of thermal energy caused by a differences in temprature and this temprature difference  is also called a temprature gradient and since heat is a movement of energy and it is measured in the same unit as energy in the joules

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(NH4)2SO4 + Ba(NO3)2 → BaSO4 + 2NH4NO3 is  net ionic balanced equations for the reaction that occurs

To balance chemical equations, stoichiometric coefficients for the reactants and products are required. This is important because a chemical equation must follow the rules of conservation of mass and constant proportions, which dictate that the same number of atoms of each element must be avail on two of the reactant and product sides of the equation.

Chemical equations use the relevant chemical formulae to symbolically express the reactants and products of a chemical process. To the left of the sign "," and to the right of the arrow symbol, respectively, is the part of the chemical equation that is on the reactant side.

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