A sheet of polyethylene 1.5-mm thick is being used as an oxygen barrier at a temperature of 600K. If the flux is 2.48 x 10-5 kg/m2 s, what concentration of oxygen must be maintained on the high-pressure side to ensure that the concentration

Answer:

Here's what I get  

Explanation:

You have an equilibrium reaction between Fe³⁺/ SCN⁻ and FeSCN²⁺.

[tex]\underbrace{\hbox{Fe$^{3+}$}}_{\text{pale yellow-green}} +\underbrace{\hbox{SCN$^{-}$}}_{\text{colourless}} \, \rightleftharpoons \, \underbrace{\hbox{Fe(SCN)$^{2+}$}}_{\text{deep blood red}} \\[/tex]

When you add AgNO₃, the Ag⁺ reacts with the SCN⁻. It forms a colourless precipitate of Ag(SCN).

Ag⁺(aq) + SCN⁻(aq) ⟶ AcSCN(s)

According to Le Châtelier's Principle, when we apply a stress to a system at equilibrium, the system will respond in a way that tends to relieve the stress.

If you add Ag⁺ to the equilibrium solution, it removes the SCN⁻ [as an Ag(SCN) precipitate].

The system responds by trying to replace the missing SCN⁻:

The Fe(SCN)²⁺ dissociates to form SCN⁻, so the position of equilibrium shifts to the left,

You now have more Fe³⁺ and SCN⁻ and less of the highly coloured Fe(SCN)²⁺ at the new equilibrium.

The deep red colour becomes less intense.

When silver nitrate is added to the Fe/SCN equilibrium,  the colourless intense and precipitate forms because it settles at the bottom.

Chemical equilibrium is the condition in the course of a reversible chemical reaction in which no net change in the amounts of reactants and products occurs.

The added silver nitrate, [tex]AgNO_3[/tex] , effectively removes thiocyanate ions, [tex]SCN^{-1}[/tex], from the equilibrium system via a precipitation reaction when the [tex]Ag^{+1}[/tex] combines with [tex]SCN^{-1}[/tex] to produce insoluble silver thiocyanate, AgSCN, which settles to the bottom of the test tube.

Ag⁺(aq) + SCN⁻(aq) ⟶ AcSCN(s)

According to Principle, when we apply stress to a system at equilibrium, the system will respond in a way that tends to relieve the stress.

Adding Ag⁺ to the equilibrium solution, it removes the SCN⁻ [as an Ag(SCN) precipitate].

The system responds by trying to replace the missing SCN⁻:

The Fe(SCN)²⁺ dissociates to form SCN⁻, so the position of equilibrium shifts to the left,

You now have more Fe³⁺ and SCN⁻ and less of the highly coloured Fe(SCN)²⁺ at the new equilibrium.

The deep red colour becomes less intense.

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Answer:

Explanation:

C₈H₁₆ + 12O₂ = 8 CO₂ + 8H₂O.

a )

Heat of formation of C₈H₁₆

[tex]\triangle H_f (C_6H_{16})=-174.5 kJ[/tex]

[tex]\triangle H_f (CO_2)=-393.5 kJ[/tex]

[tex]\triangle H_f (O_2)= 0[/tex]

[tex]\triangle H_f (H_2O)=-285.82 kJ[/tex]

[tex]\triangle H_{reaction} =[/tex] 8 x - 393.5 - 8 x 285.82 + 174.5x 1

= - 5260.06 kJ

b ) Energy required = 2.905 x 10¹⁵kJ

moles of C₈H₁₆ require to be burnt

= 2.905 x 10¹⁵ / 5260.06

= 55.23 x 10¹⁰ moles

= 55.23 x 10¹⁰ x mol weight of C₈H₁₆ g

= 55.23 x 10¹⁰ x 112 g

= 6185.5 x 10¹⁰ g

= 6185.5 x 10⁷ kg

c )

No of litres of CO₂ produced at NTP = 8 x 22.4 x 55.23 x 10¹⁰ L

=  9897.22 x 10¹⁰ L

At 1520 mm of Hg pressure and 250°C

volume of CO₂

= 9897.22  x 10¹⁰ x 760 x ( 273 + 250) / ( 1520 x 273 )

= 9480.3 x 10¹⁰ L .

Answer: [tex]4Fe+3O_2\rightarrow 2Fe_2O_3[/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 is:

[tex]4Fe+3O_2\rightarrow 2Fe_2O_3[/tex]

Thus in the reactants, there are 4 atoms of iron and 6 atoms of oxygen.Thus there will be 4 atoms of iron, and 6 atoms of oxygen in the product as well.

Answer:

A molecule is the answer.

Answer:

The element potassium forms a cation with the charge +1 . The symbol for this ion is K⁺, and the name is potassium ion. The number of electrons in this ion is 18.

Explanation:

Potassium is a metal. It belongs to the group 1 elements. Metals form cations by losing electrons. Since potassium is a group element, it forms a cation by losing one electron. The charge it has is +1 due to the excess of the protons compared t the electrons by 1.

Potassium has  19 electrons. Potassium io on the other hand has 19-1 = 18 electrons.

Answer:

A) One that occurs on its own

The approximate age of the cloth is 17190 years.

We'll begin by calculating the number of half-lives that has elapsed. This can be obtained as follow:

2ⁿ = 100 / 13

2ⁿ = 8

2ⁿ = 2³

n = 3

Finally, we shall determine the age of the cloth.

t = n × t½

t = 3  × 5730

t = 17190 years

Thus, the approximate age of the cloth is 17190 years

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Answer:

1) R₃CO , H, H₃C, a carbon free radical

2) high temperature, ultraviolet irradiation

Explanation:

1) Homolysis leads to the formation of free radicals (species having a free electron). Thus, answer is :

R₃CO

H

H₃C

a carbon free radical

2) Homolysis require high temperature, ultraviolet irradiation.

Answer:

118.4 g

Explanation:

4 Ga  +  3 S₂ → 2 Ga₂S₃

According to the equation, for every 4 moles of gallium burned, 2 moles of gallium(III) sulfide.

First, convert grams of Ga₂S₃ to moles.  The molar mass is 235.641 g/mol.

(200.0 g)/(235.641 g/mol) = 0.8487 mol

Use the relationship above to convert moles of Ga₂S₃ to moles of Ga.

(0.8487 mol Ga₂S₃) × (4 mol Ga)/(2 mol Ga₂S₃) = 1.697 mol Ga

Convert moles of Ga to grams.  The molar mass is 69.723 g/mol.

(1.697 mol Ga) × (69.723 g/mol) = 118.4 g

Answer:

D. He showed that most of an atom's mass was located in the atom's

nucleus.

Explanation:

Ernest Rutherford changed the atomic model because of his experiment which was the gold foil experiment. A beam of alpha particles was aimed at a piece of gold foil, most particles passed through but some were scattered backward which showed that the middle of an atom (nucleus) is the where most of the mass is located.

Rutherford's model of atoms is the improved version of Thomson's model. In the model, it is stated that most of an atom's mass is located in the nucleus. Thus, option D is correct.

Ernest Rutherford gave the improved atomic model that postulated the failure of Thomson's model. Rutherford's model described the atom to consist of a sub-atomic particle with a positively charged nucleus.

The nucleus is in the center of the atom and had nearly all mass concentrated in it due to the presence of the protons and neutrons. The electrons were called negatively charged species that were present in the shells around the nucleus like the planets around the Sun.

Therefore, Rutherford's model showed mass concentrated in the center of the nucleus.

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Answer:

Explanation:

The half reaction required

Fe⁺³ + 3 e = Fe

This is a balanced equation

No of atom of Fe on both side = 1

Total charge on the left side = + 3 - 3 = 0

Total charge on the right = 0

three electrons will be required to neutralise +3 charge on the single iron ion .

Answer:

Explanation:

Total mass of substance = 7.22 + 2.53 + 5.25 g

= 15 g

percentage of nickel = 7.22 x 100 / 15

= 48.13

= 48.1 %

percentage of phosphorus  = 2.53 x 100 / 15

= 16.87%  

= 16.9%

percentage of oxygen  = 5.25 x 100 / 15

= 35 %  

The percent composition of the pure substance should be 48.1%, 16.9%, and 35%.

Total mass of substance = 7.22 + 2.53 + 5.25 g

= 15 g

Now

percentage of nickel = 7.22 x 100 / 15

= 48.13

= 48.1 %

And,

percentage of phosphorus  = 2.53 x 100 / 15

= 16.87%  

= 16.9%

And, finally

percentage of oxygen  = 5.25 x 100 / 15

= 35 %  

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Answer:

Explanation: M(PCL5)= 31 + 5(35.5)

=208.5g/mol

M(H20)= 18g/mol

n(PCL5) = 75.5÷208.5

= 0.362mol

n(HCl)/n(PCL5)= 5/1

n(HCl)= 5×0.362

=1.81mol of HCl

Answer:

1a. 0.89 gcm¯³

1b. Yes.

1c. Tetrahydrofuran.

2. 0.54 g/mL

Explanation:

1. Data obtained from the question include:

Volume = 0.988 L = 988 cm³

Mass = 879 g

1a. Determination of the density

Density = mass /volume

Density = 879/ 988

Density = 0.89 gcm¯³

Therefore, the density of the liquid is 0.89 gcm¯³

1b. From the given data, it is possible to determine the identity of the liquid.

1c. The density of the liquid is 0.89 gcm¯³. Comparing the density of the liquid obtained with those given in the table, the liquid is tetrahydrofuran

2. Data obtained from the question include:

Mass of empty cylinder = 5.25 g

Mass of cylinder and sodium thiosulfate = 75.82 g

Volume = 130.63 mL

Next, we shall determine the mass of sodium thiosulfate. This can be obtain as follow:

Mass of empty cylinder = 5.25 g

Mass of cylinder and sodium thiosulfate = 75.82 g

Mass of sodium thiosulfate =.?

Mass of sodium thiosulfate = Mass of cylinder and sodium thiosulfate – Mass of empty cylinder

Mass of sodium thiosulfate = 75.82 – 5.25

Mass of sodium thiosulfate = 70.57 g

Finally, we shall determine the concentration of the sodium thiosulfate as follow:

Mass = 70.57 g

Volume = 130.63 mL

Concentration =?

Concentration = mass /volume

Concentration = 70.57/130.63

Concentration = 0.54 g/mL

The concentration of the solution is 0.54 g/mL

Answer: The mass of 405 ml of cresol is 415 grams

Explanation:

Density is defined as the mass contained per unit volume.

[tex]Density=\frac{mass}{volume}[/tex]

Given : Density of cresol = 1024 g/L

Volume of cresol = 405 ml = 0.405 L   ( 1L=1000ml)

Putting in the values we get:

[tex]1024g/L=\frac{mass}{0.405L}[/tex]

[tex]mass=1024g/L\times 0.405L=415g[/tex]

Thus mass of 405 ml of cresol is 415 grams

Answer:

0.025 M

Explanation:

The following data were obtained from the question:

Initial volume (V1) = 5 mL

Initial concentration (C1) = 0.5 M

Final volume (V2) = 100 mL

Final concentration (C2) =..?

Using the dilution formula, we can obtain the final concentration of the diluted solution as follow:

C1V1 = C2V2

0.5 x 5 = C2 x 100

Divide both side by 100

C2 = (0.5 x 5)/100

C2 = 0.025 M

Therefore, the final concentration of the diluted solution is 0.025 M

The concentration of the final diluted solution is 0.025M

The dilution formula is expressed according to the formula:

[tex]C_1V_1=C_2V_2[/tex]

Given the following parameters

[tex]C_1=0.5M\\V_1=5.00mL\\V_2=100.0mL\\C_2=?[/tex]

Substitute the given parameters into the formula:

[tex]C_1V_1=C_2V_2\\0.5(5)=100C_2\\2.5=100C_2\\C_2=\frac{2.5}{100}\\C_2= 0.025M[/tex]

Hence the concentration of the final diluted solution is 0.025M

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Answer:

1 g

Explanation:

From the formula;

N/No = (1/2)^t/t1/2

Where;

N= mass of radioactive element left after a time t = the unknown

No= mass of radioactive element originally present in the sample = 8g

t= time taken for N mass of the sample to remain = 1500

t1/2= half-life of the radioactive element = 500 years

Substituting values, we have;

N/8 = (1/2)^1500/500

N/8 = (1/2)^3

N/8 = 1/8

N= 1/8 ×8

N= 1 g

Therefore; mass of radioactive element left after 1500 years is 1 g

Answer:

2ErF3 + 3Mg → 2Er + 3MgF2

Explanation:

Erbium metal is a member of the lanthaniod series. It reacts with halogens directly to yield erbium III halides such as erbium III chloride, Erbium III fluoride etc.

Erbium metal (Er) can be prepared by reacting erbium(III) fluoride with magnesium; the products are erbium metal and magnesium fluoride. This is a normal redox process in which the Erbium metal is reduced while the magnesium is oxidized. The balanced reaction equation of this process is; 2ErF3 + 3Mg → 2Er + 3MgF2

Considering the definition of bond and the different type of bonds, valence is not one of  the types of bonds.

A chemical bond is defined as the force by which the atoms of a compound are held together. These are electromagnetic forces that give rise to different types of chemical bonds.

In other words, a chemical bond is the force that joins atoms to form chemical compounds and confers stability to the resulting compound.

The covalent bond is the chemical bond between atoms where electrons are shared, forming a molecule. Covalent bonds are established between non-metallic elements, such as hydrogen H, oxygen O and chlorine Cl. These elements have many electrons in their outermost level (valence electrons) and have a tendency to gain electrons to acquire the stability of the electronic structure of noble gas. The shared electron pair is common to the two atoms and holds them together.

An ionic bond is produced between metallic and non-metallic atoms, where electrons are completely transferred from one atom to another. During this process, one atom loses electrons and another one gains them, forming ions.

Metallic bonds are a type of chemical bond that occurs only between atoms of the same metallic element. In this way, metals achieve extremely compact, solid and resistant molecular structures, since the atoms that share their valence electrons.

In summary, valence is not one of  the types of bonds. The types of bonds are covalent, ionic and metallic.

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Answer:

The various sources of such errors are given below.

Explanation:

So that the percentage of someone specific produces heat exploratory value systems inaccuracies can be somewhat massive.

Answer:

14.3mL you require to reach the half-equivalence point

Explanation:

A strong acid as HClO₄ reacts with a weak base as CH₃CH₂NH₂, thus:

CH₃CH₂NH₂ + HClO₄ → CH₃CH₂NH₃⁺ + ClO₄⁻

As the reaction is 1:1, to reach the equivalence point you require to add the moles of HClO₄ equal to moles CH₃CH₂NH₂ you add originally. Also, half-equivalence point requires to add half-moles of CH₃CH₂NH₂ you add originally.

Initial moles of CH₃CH₂NH₂ are:

20.8mL = 0.0208L × (0.51mol CH₃CH₂NH₂ / 1L) =

0.0106moles CH₃CH₂NH₂

To reach the half-equivalence point you require:

0.0106moles ÷ 2 = 0.005304 moles HClO₄

As concentration of HClO₄ is 0.37M, volume you require to add 0.005304moles is:

0.005304 moles HClO₄ ₓ (1L / 0.37mol) = 0.0143L =

When The Kb of ethylamine is 6.5 x 10-4 is = 14.3mL you require to reach the half-equivalence point.

When A strong acid as HClO₄ reacts with a weak base as CH₃CH₂NH₂, Therefore:

Then CH₃CH₂NH₂ + HClO₄ → CH₃CH₂NH₃⁺ + ClO₄⁻

So when the reaction is 1:1, to reach the equivalence point then you instruct to that add the moles of HClO₄ equal to the moles CH₃CH₂NH₂ you add originally. Also, When the half-equivalence point requires you to add half-moles of CH₃CH₂NH₂ you add originally.

Then Initial moles of CH₃CH₂NH₂ are:

After that 20.8mL = 0.0208L × (0.51mol CH₃CH₂NH₂ / 1L) =

Then 0.0106moles CH₃CH₂NH₂To get the half-equivalence point you require is:

Then 0.0106moles ÷ 2 = 0.005304 moles HClO₄

After that As the concentration of HClO₄ is 0.37M, the volume you require to add 0.005304moles is:

Then 0.005304 moles HClO₄ ₓ (1L / 0.37mol) = 0.0143L =

Therefore, 14.3mL you require to reach the half-equivalence point.

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Answer:

284 calories

Explanation:

There are 284 calories in 50 grams of peanuts.

Calorie breakdown: 73% fat, 11% carbs, 17% protein.

Answer:

1.22 × 10³ g

Explanation:

Step 1: Write the balanced equation

P₄O₁₀ + 6 H₂O ⇒ 4 H₃PO₄

Step 2: Calculate the moles of H₃PO₄ produced by 3.10 moles of P₄O₁₀

The molar ratio of P₄O₁₀ to H₃PO₄ is 1:4. The moles of H₃PO₄ produced are 4/1 × 3.10 mol = 12.4 mol

Step 3: Calculate the mass corresponding to 12.4 moles of H₃PO₄

The molar mass of H₃PO₄ is 97.99 g/mol.

[tex]12.4 mol \times \frac{97.99g}{mol} = 1.22 \times 10^{3} g[/tex]

Answer:

the density if vinegar will also be needed

Explanation:

Because this is an experiment of volumetric analysis

Answer:

C8H17N

Explanation:

Mass of the unknown compound = 5.024 mg

Mass of CO2 = 13.90 mg

Mass of H2O = 6.048 mg

Next, we shall determine the mass of carbon, hydrogen and nitrogen present in the compound. This is illustrated below:

For carbon, C:

Molar mass of CO2 = 12 + (2x16) = 44g/mol

Mass of C = 12/44 x 13.90 = 3.791 mg

For hydrogen, H:

Molar mass of H2O = (2x1) + 16 = 18g/mol

Mass of H = 2/18 x 6.048 = 0.672 mg

For nitrogen, N:

Mass N = mass of unknown – (mass of C + mass of H)

Mass of N = 5.024 – (3.791 + 0.672)

Mass of N = 0.561 mg

Now, we can obtain the empirical formula for the compound as follow:

C = 3.791 mg

H = 0.672 mg

N = 0.561 mg

Divide each by their molar mass

C = 3.791 / 12 = 0.316

H = 0.672 / 1 = 0.672

N = 0.561 / 14 = 0.040

Divide by the smallest

C = 0.316 / 0.04 = 8

H = 0.672 / 0.04 = 17

N = 0.040 / 0.04 = 1

Therefore, the empirical formula for the compound is C8H17N

Answer:

Dissolving NH4F in water will form a weak acidic solution.

Explanation:

That it is a weak acid solution means that it has a pH below 7 but close to the value, that is, it does not contain as many acids as those substances that are around a pH of 1 to 4, generally weak acids have a pH approximately 5 to 6

The solution of solid ammonium fluoride in pure water has been slightly acidic in nature.

Ammonium fluoride has been an ionic compound formed by the interaction of cationic ammonia and anionic fluoride ions. The dissolution of ionic compounds will result in the compound in its dissociated ionic state.

The dissociation results in the formation of ammonium cation. The ammonium has been a strong acid.

The resulted anion has been fluoride. It has been a strong base, but slightly weaker than ammonia.

Thus the resultant solution will result in slightly acidic nature.

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Answer:

[tex]m=368 g[/tex]

Explanation:

Hello,

In this case, in order to compute the required mass, we first must notice that 6.022x10²³ formula units of sodium sulfate contain 1 mole of such compound (Avogadro's relationship). Moreover, one mole of sodium sulfate contains 142.04 g, which is in fact, the molar mass. Thereby, the required mass is computed via the following mole-mass-particles relationship:

[tex]m=1.56x10^{24}f.u*\frac{1mol}{6.022x10^{23}f.u}*\frac{142.04g}{1mol} \\\\m=368 g[/tex]

Regards.

Answer:

Cooking a pot of soup

Explanation:

id say that because when you freeze ice cream, its already frozen, so no heat is being released. melting ice wouldn't be the answer because, once again, it is already frozen, and no heat is being released.

Answer:

the correct answer is freezing ice cream

Explanation:

i took the test & got this question correct. also, heat energy is released when freezing because there is no heat energy involved.

Answer:

Temperature

Explanation:

Kinetic energy of gass molecules is directly propotional to the temperature.

Answer:

It is important to separate mixture into pure or relatively pure substances when performing a chemical analysis SO AS TO KNOW THE PROPERTIES COMING FROM EACH PART MIXTURE WHICH MAY INTERFERE WITH THE SEPARATION.

Explanation:

In chemistry, Mixture is the combination of two or more substances which are not combine chemically.

Mixture contain different substances with different physical and chemical properties.

It is important to purify the substances in a mixture so as to identify what properties are coming from each mixture and also some part of the mixture can interfere with the properties of other mixture present for skewing analysis.