Which of the following is not an indication of a chemical change?
A. Fracture Formation
B. Energy transfer
C. Precipitate formation.
D. Gas production

Answer:

see explanation

Explanation:

Pure water (H₂O) at 25°C follows an autoionization mechanism. That is, water reacts with itself to yield Hydronium Ions (H₃O⁺) and Hydroxide Ions (OH⁻) according to the following proton transfer mechanism.

2H₂O(l) ⇄ H₃O⁺(aq) + OH⁻(aq) => H₂O(I) ⇄ H⁺(aq) + OH⁻(aq) as a shorthand form of the process primarily for convenience. The H⁺ ion is a proton and would not be found in solution as an independent free form particle, but the shorthand format is generally accepted in the chemical community because of it's ease of application.

Other related facts of water ionization include...

At 25°C/1atm => the molar concentrations of  [H⁺(aq)]  = 1 x 10⁻⁷M and [OH⁻(aq)] = 1 x 10⁻⁷M

Applying to the equilibrium ionization expression for water ...

                H₂O(I) ⇄    H⁺(aq)      +      OH⁻(aq)

C(eq):          ∞*         1 x 10⁻⁷M          1 x 10⁻⁷M

*The molar concentration of water is considered to be infinite [∞] as compared to concentration values of H⁺(aq) and OH⁻(aq) and is for practical purposes assumed to be constant. This leads to the classic Ionization Product constant expression for water (Kw = [H⁺(aq)][OH⁻(aq)].

The value for Kw at 25°C/1atm is then ...

Kw =  [H⁺(aq)][OH⁻(aq)] = (1 x 10⁻⁷M)(1 x 10⁻⁷M) = 1 x 10⁻¹⁴M² (units are typically dropped and Kw listed simply as 1 x 10⁻¹⁴.

With this, the terms acidity, neutral and alkaline acid base systems are defined and related to pH. That is, if ...

[H⁺(aq)] > [OH⁻(aq)] => Acidic System => pH < 7

[H⁺(aq)] = [OH⁻(aq)] => Neutral System => pH = 7

[H⁺(aq)] < [OH⁻(aq)] => Alkaline System => pH < 7

pH = -log[H⁺]  and pOH = -log[OH⁻] and pH + pOH = 14.

Answer:

2.6 × 10³ g Al

74 mol O₂

Explanation:

Aluminum oxide decomposes into aluminum and oxygen, according to the following balanced equation.

2 Al₂O₃ ⇒ 4 Al + 3 O₂

Step 1: Calculate the moles corresponding to 5.0 kg of aluminum oxide

The molar mass of aluminum oxide is 101.96 g/mol.

[tex]5.0 \times 10^{3} g \times \frac{1mol}{101.96g} = 49mol[/tex]

Step 2: Calculate the mass of aluminum formed

We will use the following relations.

[tex]49molAl_2O_3 \times \frac{4molAl}{2molAl_2O_3} \times \frac{26.98gAl}{1molAl} = 2.6 \times 10^{3} gAl[/tex]

Step 3: Calculate the moles of oxygen produced

The molar ratio of Al₂O₃ to O₂ is 2:3. Then,

[tex]49molAl_2O_3 \times \frac{3molO_2}{2molAl_2O_3} =74molO_2[/tex]

Answer:

[tex]\frac{40}{18}Ar => \frac{40}{17}Cl + \frac{0}{1}e\\[/tex]

Explanation:

The process of positron emission is better understood by the following reaction:

Positron emission may be defined as a subordinate type of radioactive decay called which is effectively known as beta decay. Due to this emission, a proton that is present inside a radionuclide nucleus significantly transformed into a neutron while liberating a positron and an electron neutrino.

According to the context of this question, Argon-40 undergoes the process of beta decay. Through which X element is formed which is known as chlorine. The atomic number (Z) of chlorine is 17, while the atomic mass (A) is 40 which is as identical to argon.

Therefore, the appropriate values for A and Z and the chemical symbol for X are 40 and 17 respectively.

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Answer:

LiF and RbBr

Explanation:

Salt is an ionic compound that is made from the reaction of an acid and a base solution. Salts dissolve in water to give solutions that are acidic, basic, or neutral.

Salt formed from a strong acid and a weak base will make an acidic solution when added to water. The reason this occurs is because when the salt dissociates, the conjugate acid of the weak base will donate a proton, or one hydrogen ion, to water and form hydronium ion.

If a salt is formed from a weak acid and a strong base, it dissolves in water and the conjugate base of the weak acid will accept a proton from water and yield the hydroxide ion. Hence the solution of the salt will be basic.

If the salt is formed from a strong acid and a strong base, the salt is neutral when dissolved in water. Both LiF and RbBr are formed from strong acids and strong bases hence they will have a pH of 7.0 in solution.

LiF RbBr NaClO4 NH4Cl is = LiF and RbBr The correction is 'C'.

Salt is an ionic mixture that is made from the reaction of an acid and a base resolution. Salts liquefy in water to give solutions that are acidic, basic, or neutral.

Salt constructed from a strong acid and a breakable base will make an acidic solution when added to water. The reason this occurs is that when the salt dissociates, the conjugate acid of the weak base will donate a proton, or one hydrogen ion, to water and form a hydronium ion.

If a grain of salt is formed from a weak acid and a powerful ground, it liquefies in water and the conjugate bottom of the weak acid will accept a proton from water and yield the hydroxide ion. Therefore, the solution of the salt will be basic.

If the salt is formed from a strong acid and a strong bottom, the salt is neutral when liquefied in water. Both LiF and also RbBr are formed from strong acids and powerful bases hence they will have a pH of 7.0 in resolution.

Therefore, the Correct option is 'C'

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Explanation:

Entropy of a reaction ΔS∘rxn is the degree of disoderliness in a system. Gases generally have a higher degree of disorder compared to liquids. Hence for the reaction 2H2(g)+O2(g) ⟶ 2H2O(l), the entropy decreases sice the reactants are in the gaseous state and the products is in the liquid state of matter

Answer:

Acanthite. MFCD00003406

Explanation:

Answer:

A. Ductility, because it can be observed by altering the shape of the substance  

Explanation:

Changing the shape of a substance does not change its identity.

Answer:

c

Explanation:

Answer: [tex]Na_2CO_3+2HCl\rightarrow 2NaCl+H_2O+CO_2[/tex]

Explanation:

According to the law of conservation of mass, mass can neither be created nor be destroyed. Thus the mass of products has to be equal to the mass of reactants. The number of atoms of each element has to be same on reactant and product side. Thus chemical equations are balanced.

The balanced chemical equation will be:

[tex]1Na_2CO_3+2HCl\rightarrow 2NaCl+H_2O+1CO_2[/tex]

Thus the numbers that go in the blanks are 1, 2, 2, and 1 respectively for [tex]Na_2CO_3[/tex], [tex]HCl[/tex] , [tex]NaCl[/tex] and [tex]CO_2[/tex] respectively.

Answer:

6 cm Hg

Explanation:

Boyles Law: P1V1=P2V2

(100 mL)(x)=(20 mL)(30 cm Hg)

x = 6 cm Hg

*Text me at 561-400-5105 for private tutoring if interested: I can do homework, labs, and other assignments :)

Answer:

MRCORRECT has answered the question

Explanation:

Film photography is another example ofchemical reaction by light. In this example, the chemical compounds coated on the film go through a chemical reaction. ... These plates (usually made of aluminum) are coated with a photosensitive compound consisting of a polymer and a photosensitivechemical system.

Answer:

2.0 x 10^-2 kg/mol

Explanation:

Answer:

Check the explanation

Explanation:

Sample volume V= 10 mL/min x 17 h x 60 min/h / 1000 mL/L = 10.2 L

The concentration is increased

             10200 mL (sample volum) / 10 mL (eluted sample) = 1020 times.

57x10-9 M / 1020 = 5.6x10-12 M    

1.5 M HNO3 will contain ≤ 2ppm x (1.5M/15.7M ) ≤ 0.190 ppm ≤ 190 ppb

Ignoring this is reagent impurity and calculating for sea water

≤ 190 ppb /1020 = 0.186 ppb = 0.186 x 10-9g/mL = 0.186 x 10-6g/L =

0.186 x 10-6g/L / 56 g/mol = 0.003 x10-6 M = 3 nM

Answer:

0.10 amps

Explanation:

The rate of a chemical reaction is defined as the change in the concentration of a reactant or a product over the change in time, and concentration is in moles per liter, or molar, and time is in seconds. So we express the rate of a chemical reaction in molar per second.

Answer:

Hey!

Your answer is The Rate of a Reaction is a measurement of how the speed at which a reactant is used up / or a product is formed.

Explanation:

R of R (Rate of Reaction) can be affected by:

Reactant concentration (how much of the substance is there to react)

The state of the reactants (whether they are in a solid/liquid/gas state)

The total surface area (more particles of the substance means more reactions...)

The Temperature (hot=quicker cool=slower)

The presence of a catalyst (catalysts speed up the Rate of the Reaction)

HOPE THIS HELPS!!

Answer:

A. Buffer strips

Explanation:

The practice that could help reduce erosion of water banks is buffer strips.

Erosion is the action of surface processes that removes soil, rock or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited.

One of the practices that could be used to reduce the effect of erosion is buffer strips.

What buffer strips do is slow and filter storm runoff while helping to hold soil in place.

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Answer:

See explaination

Explanation:

Please kindly check attachment for the step by step solution of the given problem

Answer:

The reaction involves two steps and occurs fastest with tertiary alkyl halides

Explanation:

To solve such this we must know the concept of nucleophilic substitution reaction. The reaction involves two steps and occurs fastest with tertiary alkyl halides. Therefore, the correct option is option A.

Chemical reaction is a process in which two or more than two molecules collide in right orientation and energy to form a new chemical compound. The mass of the overall reaction should be conserved. There are so many types of chemical reaction reaction like combination reaction, double displacement reaction.

The characteristics of SN1 mechanism:

SN1 reaction is a nucleophilic substitution reaction.

Leaving group, a nucleophile, electrophile and a solvent are present

Two types of enantiomers can be formed in the reaction depending on the preference of the nucleophile.

The first step is the slowest because a bond is being broken.

SN1 reaction involves two steps and occurs fastest with tertiary alkyl halides

Therefore, the correct option is option A.

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Answer:

this si from google hope it helps

Explanation:

The Main Causes of Water Pollution in the U.S.

Runoff from Agricultural Operations. Agriculture represents one of the biggest sources of water pollution in the country. ...

Runoff and Nonpoint Source Pollution. ...

Industrial Activities. ...

Leakage from Underground Storage and Piping. ...

Leaking Sewers. ...

Vehicle Emissions. ...

Landfill Leakage. ...

Hazardous Waste.

Answer:

Runoff and Non-point Source Pollution.

Explanation:

it's caused by rainfall or snow-melt moving over and through the ground. As the runoff moves, it picks up and carries away natural and human-made pollutants, finally depositing them into lakes, rivers, wetlands, coastal waters and ground and NPS is it's abbreviation.

Answer:

C

Explanation:

Answer:

I think its q

Explanation:

h is the Planck constant, c the speed of light

Answer:

wHeRe ArE tHe StAtEmEnTs mAn

Answer:

0.517

Explanation:

HCN + NaOH → NaCN + H2O [balanced as written]

(35.4 mL) x (0.268 M NaOH) x (1 mol HCN / 1 mol NaOH) / (18.35 mL HCN) = 0.517 M HCN

Answer: 0.517

Explanation:

Answer:

A) An element with the valence electron configuration 5s¹ would form a monatomic ion with a charge of +1. In order to form this ion, the element will lose electron(s) from/into the 5s subshell(s).

B) An element with the valence electron configuration 2s²2p⁴ would form a monatomic ion with a charge of +1. In order to form this ion, the element will lose electron(s) from/into the 2p (2pₓ specifically) subshell(s).

Explanation:

The secret to this task is to follow those rules for the stability of electronic structures of elements. The rules include

- Electrons are filled firstly into shells or subshells of lower energies first.

- While filling electronic structure or writing electronic structures for elements/ions, electrons are fed singly to the suborbital before pairing occurs, this is because the totally paired up electrons of a suborbital are more stable than the totally unpaired electrons of the same suborbital which is now in turn more stable than the combination of paired and unpaired electrons in the suborbitals.

A) For an element with its valence electron on 5s¹, this means that there is one valence electron on this atom's outermost shell and outermost suborbitals. So, to form a monoatomic ion, it would take between losing and gaining an electron. Gaining an electron leads to a 5s², which indicates empty 5p orbitals too and is therefore less stable than losing an electron which would lead to the loss of the shell 5 and focus on a completely filled 4-shell.

So, losing the electron from the 5s suborbital to become a monotonic ion makes it acquire a charge of +1.

B) Just like the explanation in (A), to form a monoatomic ion would require a loss or gain of an electron. With valence electrons 2s²2p⁴, gaining an electron would have led to a 2s²2p⁵ and a further breakdown as 2s²2pₓ²2pᵧ²2pz¹ which has unpaired and paired electrons in the 2p suborbital. This is evidently less stable than if an electron was lost, the valence electrons are 2s²2p³ and they are positioned in a totally unpaired fashion in the 2p suborbital as 2s²2pₓ¹2pᵧ¹2pz¹.

Hence, the more stable alternative is more likely to occur and the electron is lost from the 2pₓ suborbital to make the monoatomic ion of the element acquire a +1 charge status too because of lost electron too.

Hope this Helps!!!

The octet rule states that the atoms of the elements bond to each other in an attempt to complete their valence shell with eight electrons. In other words, the atoms will tend to give up or share electrons to complete eight electrons in the valence shell through an ionic, covalent or metallic bond.

In other words, the goal is to have the closest noble gas electron configuration, thus having the last complete electron shell and acquiring stability.

So, in this case, to comply with the octet rule:

A. An element with the valence electron configuration 5s¹ would form a monatomic ion with a charge of +1. In order to form this ion, the element will lose one electron from the 5s subshell.

For an element with its valence electron at 5s¹, this means that there is one valence electron in the outermost shell of this atom and in the outermost suborbitals. To form a monatomic ion, it would be necessary between losing or gaining an electron and that ion is stable. It takes less energy to lose the electron of the suborbital 5s and acquire a charge of of +1, than to acquire an electron, because it forms the 5s² suborbital, which indicates empty 5p orbitals too and is therefore less stable.

Also, in this way, the octet rule is fulfilled.

B. An element with the valence electron configuration 2s²2p⁴ would form a monatomic ion with a charge of -2. In order to form this ion, the element will gain two electron into the 2p subshell(s).

After gain two electron the atom has eight electrons in its valence shell, giving it the same electronic configuration as a noble gas (2s²2p⁶). In this way, the octet rule is fulfilled and the ion is stable.

Learn more:

Answer:

The correct answer to the following question will be "0.0013%".

Explanation:

The given values are:

Weight of an empty dish = 1.0041 ± 0.0002 g

Weight of dish + sodium chloride (NaCl) = 3.2933 ± 0.0002 g

Weight of NaCl = 2.2892 ± 0.0002 g

Now,

Volume of the solution = 500.00 ± 0.05 ± 0.0002

                                      = 500.00 ± 0.0502 ml

So,

Molarity = [tex]\frac{W \ NaCl}{M \ NaCl} \times \frac{1000}{Volumes \ of \ solution}[/tex]

On putting the values in the above formula, we get

             = [tex]\frac{(2.2892\addeq +0.0002)}{58.440}\times \frac{1050}{(500.00+0.0502)}[/tex]

             = ([tex]3.917[/tex] ± [tex]0.0002[/tex]) × ([tex]2[/tex] ± [tex]0.0502[/tex])

             = ([tex]0.7834[/tex] ± [tex].00001004[/tex])

Now,

Absolute error = [tex]\frac{0.00001004}{0.7834}\times 100[/tex]

                         = [tex]0.0013[/tex]%

Answer:

$95

Explanation:

.75 x 120 = 90

90+5 = 95

Explanation:

6.02×1023 culture atoms have a mass of 63.5g. 12.0g. c +23.0g O2__44.0g CO2.(12.0+16.0+16.0=44.0g).1 mol 1 mol. 1 mol number molecules weight

The number of molecules in one mole of carbon dioxide is 6.02 × 10²³. Therefore, the number of moles of carbon dioxide which contains 4.11 × 10²³ molecules is 0.68.

The number of atoms that constitutes one mole of a substance is called Avogadro number. It is equal to  6.02 × 10²³. Thus, one mole of every elements contains Avogadro number of atoms.

Similarly, one mole of a compound contains  6.02 × 10²³ number of molecules. Thus, one mole of carbon dioxide contains these much molecules.

Given the number of molecules of carbon dioxide = 4.11 × 10²³

Then, no.of moles = number of molecules/ Avogadro number.

no.of moles = 4.11 × 10²³ /6.022 × 10²³  = 0.68.

Therefore, the number of moles of CO₂ that contains 4.11 × 10²³  molecules is 0.68.

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