You sealed an Erlenmeyer flask that was determined to have a volume of 272.2 mL with a stopper. The density of air at 25°C is 0.001185 g/mL. Air has an effective molar mass of 28.96 g/mol. What amount of air was sealed in the flask?

Answer:

283.725 kJ ⋅ mol − 1

Explanation:

C(s) + 2Br2(g) ⇒ CBr4(g) , Δ H ∘ = 29.4 kJ ⋅ mol − 1

[tex]\frac{1}{2}[/tex]Br2(g) ⇒ Br(g) ,  Δ H ∘ = 111.9 kJ ⋅ mol − 1

C(s) ⇒ C(g) ,  Δ H ∘ = 716.7 kJ ⋅ mol − 1

4*eqn(2) + eqn(3) ⇒ 2Br2(g) + C(s) ⇒ 4 Br(g) + C(g) , Δ H ∘ = 1164.3 kJ ⋅ mol − 1

eqn(1) - eqn(4) ⇒ 4 Br(g) + C(g) ⇒ CBr4(g) , Δ H ∘ = -1134.9 kJ ⋅ mol − 1

so,

   average bond enthalpy is [tex]\frac{1134.9}{4}[/tex] = 283.725 kJ ⋅ mol − 1

The  average molar bond enthalpy of the carbon‑bromine bond in a CBr 4 molecule is 283.725 kJ ⋅ mol − 1

C(s) + 2Br2(g) ⇒ CBr4(g) , Δ H ∘ = 29.4 kJ ⋅ mol − 1

Br2(g) ⇒ Br(g) ,  Δ H ∘ = 111.9 kJ ⋅ mol − 1

C(s) ⇒ C(g) ,  Δ H ∘ = 716.7 kJ ⋅ mol − 1

4*eqn(2) + eqn(3)

⇒ 2Br2(g) + C(s)

⇒ 4 Br(g) + C(g) , Δ H ∘

= 1164.3 kJ ⋅ mol − 1

eqn(1) - eqn(4)

⇒ 4 Br(g) + C(g)

⇒ CBr4(g) , Δ H ∘

= -1134.9 kJ ⋅ mol − 1

so,

average bond enthalpy is  = 283.725 kJ ⋅ mol − 1

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In Lewis structures, all X-O bonds have the same length in NO3 -, SO4 2-, and BrO3 -. This is due to resonance, whereby the electron density is distributed among multiple equivalent structures.

In the Lewis structures of the given oxyanions, the ions in which all X-O bonds have the same length are: (ii) NO3 -, (iv) SO4 2-, and (v) BrO3 -. The concept of bond length in these ions is connected to the principle of resonance. Each of these ions exhibit resonance, which means the electron density is distributed among more than one equivalent Lewis structures. This leads to the bonds having the same length. For example, in the SO4 2- ion, there are multiple resonance structures, each involving double bonds between the sulfur and the different oxygen atoms. As these double bonds can 'move' about the ion (due toan resonce), the four sulfur-oxygen bonds are of equal length. Such a phenomenon is not present in (i) NO2 - and (iii) SO3 2-.

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Final answer:

The NO2- ion has all X-O bonds with the same length.

Explanation:

The Lewis structure of an ion represents the arrangement of atoms and electrons in the ion.

In the oxyanions provided, only NO2- has all X-O bonds (X representing the central atom) with the same length.

This is because the NO2- ion has resonance structures, which means the double bond can be located between either of the two oxygen atoms. As a result, the N-O bonds in NO2- are identical in length.

Answer:

Explanation:

It wouldn't be able to separate negative gram from positive. it would not wash away some of the crystal violet stain effectively. Gram - Cells will appear to be the same hue. Water can also dilute cells or wash them off the slide

Answer:

Explanation:

Would not be able to differentiate gram - from + it would not efficiently wash some of the crystal violet stain away. gram - cells will still remain the same color. also water may dilute or wash cells off the slide

Answer: B (Items with densities lower than water will sink due to surface tension)

Explanation:

Surface tension is an intermolecular force exerted on the surface of water making it like a stretch elastic skin. Surface tension enables items with lesser densities than water, to float and slide on a water surface. Examples insects, leaves, paper etc

According to Archimedes principle an object denser than the fluid will sink. While objects less dense than the fluid will float.

Answer is (B) is false because items with densities higher then water will sink due to surface tension

Items with densities lower than water will sink due to surface tension. Therefore, the correct option is option B.

A intriguing phenomena called surface tension occurs when a liquid meets a gas or another liquid. It results from the cohesive forces between the molecules that are present at a liquid's surface. Surface tension is a result of the thin layer that is formed by these cohesive forces that holds the molecules closely together. A liquid droplet placed on a surface can be used to illustrate the idea of surface tension. The droplet takes on a spherical shape as a result of the cohesive forces between the water molecules. The molecules at the surface are drawn inside to reduce their exposure to the surroundings.

Therefore, the correct option is option B.

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Answer:

3,4-dibromo 2-methylheptane

Explanation:

Alkynes can be synthesized by using sodium amide in liquid ammonia, when the starting material is a vicinal dibromoalkane. This means an alkane in which there's a Br group in two carbons next to one another.

In the attached picture you can see the reaction.

Answer:

see picture

Explanation:

Although the previous answer may be correct, the question is incomplete, the completed question is:

Draw the structure of the starting material needed to make 2-methylhept-3-yne using sodium amide in liquid ammonia followed by 1-bromopropane.

Now, the previous answer is also incorrect, because the starting material with the two bromine in carbon 3 and 4, the first reaction taking place is the substracting of the hydrogen from carbon 5, and not carbon 3 because it's bulkier than carbon 5. So the majority product formed will be a double bonded product and not a triple bond. Therefore, this answer is incorrect.

Now, that we have completed the question the Starting material would have to be the following:

CH3 - CH(CH3) - C ≡ CH

When this reactant, is in presence of NaNH2, the NH2 substract the Hydrogen from carbon 1, and then, this will attack as nucleophyle to the carbon 1 of the bromopropane and formed the desired product.

The mechanism is as following in the picture.

Final answer:

Elements within the same group or family on the periodic table have the most similar chemical properties due to their identical number of valence electrons. Examples include alkali metals such as lithium and sodium, and halogens like fluorine and chlorine.

Explanation:

Elements that have the most similar chemical properties are typically found within the same group on the periodic table. Groups, also known as families, contain elements with the same number of valence electrons. For example, the alkali metals such as lithium (Li) and sodium (Na) have one valence electron, making them highly reactive and sharing similar chemical behaviors like forming compounds with oxygen in a 2:1 ratio.

Similarly, alkaline earth metals like beryllium (Be) and magnesium (Mg) each have two valence electrons and also show close chemical properties. The halogens—including fluorine (F) and chlorine (Cl)—each have seven valence electrons, leading to their characteristic reactivity and ability to form compounds with elements such as sodium.

As elements share the same number of valence electrons, it leads to similarities in the ways they lose, gain, or share electrons during chemical reactions. The patterns of chemical properties extend beyond single groups; for instance, metallic character increases as one moves down a group in the periodic table.

Answer:

[tex]PO_4^{-3} < NO_3^- < Na^+[/tex]

Explanation:

Solutions.

a) 100 ml 1 M of Na3PO4

b) 100 ml 1 M of AgNO3

c) Mixture: 200 ml 0.5 M of Na3PO4 and 0.5 M of AgNO3

Reaction:

[tex] 3 Ag^+ + PO_4^{-3} \longrightarrow Ag_3PO_4[/tex]

So if silver ion is consumed almost completely:

[tex][Ag^+]=0 M[/tex]

[tex][PO_4^{-3}]=0.5 M-0.5 M \frac{1 mol PO4}{3 mol Ag}=0.33 M[/tex]

[tex][Na^+]=0.5 M *  \frac{3 mol Na}{mol Na_3PO_4}=1.5 M[/tex]

[tex][NO_3^-]=0.5 M[/tex]

In increasing order of concentration:

[tex]PO_4^{-3} < NO_3^- < Na^+[/tex]

The correct order of ions remaining in solution after mixing Na3PO4 with AgNO3, by increasing concentration, is phosphate (PO43-), nitrate (NO3-), and sodium (Na+), which is option (A).

When 100 ml of 1.0 M Na3PO4 is mixed with 100 ml of 1.0 M AgNO3, a reaction occurs where silver phosphate (Ag3PO4), a yellow precipitate, forms due to its low solubility and Ag+ ions become almost absent in the solution. The remaining ions in the solution will be Na+, NO3-, and a very small amount of PO43-. Since all of the Ag+ reacts to form the precipitate, we can assume that there are three times as many Na+ ions compared to PO43- ions originally, because each formula unit of Na3PO4 produces three sodium ions. Therefore, this leaves Na+ with the highest concentration in solution. NO3- concentration remains unchanged because it is a spectator ion and does not participate in the reaction.

The correct order of ions in solution by increasing concentration is PO43- < NO3- < Na+, which corresponds to option (A).

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In spite of ethylene and benzene has double bonded carbon-carbon, Benzene is a cyclic molecule with a special property called aromaticity. Aromaticity gives to the ring electronic properties which makes harder for benzene being reactive as ethylene.

Benzene has the formula C6H6 being cyclic and aromatic because have conjugated double bonds and those double bonds has a property called resonance unusual elevated making the structure very stable. That can be seen under the conditions of reaction of alkene compounds in which benzene doesn't react, like bromination with Br2 in CCl4.

On the other hand, ethylene is an alkene which has the formula C2H4, the double bond carbon carbon is available to suffer the different reactions of alkenes being more reactive.

Ethylene is more reactive than benzene primarily due to ethylene's discrete, highly reactive double bond, compared to benzene's delocalized and stabilized double bonds within its aromatic ring. The stability of the delocalized electrons in the benzene ring reduces its reactivity, while ethylene's electron-rich double bond invites addition reactions.

The difference in reactivity between ethylene (C2H4) and benzene (C6H6) toward molecular bromine is primarily due to the structural differences in their carbon-carbon double bonds. Ethylene contains a discrete C=C double bond that is highly reactive because it can open up to allow additional atoms to attach to the carbon atoms (an addition reaction). In contrast, the C=C bonds in benzene are part of a delocalized electron system over the entire aromatic ring, giving it extraordinary stability. This delocalization makes benzene less reactive towards addition reactions, such as with bromine, because the addition would disrupt the stable aromatic system.

Benzene's unique stability is due to the alternating single and double C-C bonds, which form a resonance-stabilized structure. This stability is a concept commonly understood as aromaticity, which significantly reduces the chemical reactivity of benzene's double bonds compared to those in alkenes like ethylene. Although the C=C bond is nonpolar, the reactivity of ethylene is also influenced by the electron-rich region around the σ bond, making it more prone to reactions with nucleophiles.

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Answer:

The mass of a solute divided by the mass of a solution times 100

Explanation:

The concentration of a solution refers to how much of a solute is dissolved in an amount of solvent. To express this concentration exist different methods, the mass percent concentration is one of them and is defined as the mass of a solute divided by the mass of a solution times 100:

%m/m= (mass of a solute/mass of solution)x100

Where the mass of the solution is the sum of the mass of solute and mass of solvent.

%m/m is commonly used when you can measure the masses of both solute and solution.

I hope you find this information useful and interesting! Good luck!

Mass percent in chemistry denotes the proportion of a solute in a solution in terms of a percentage. It's calculated as: Mass Percent = (mass of solute/mass of solution) * 100.

The mass percent concentration of a solution signifies the proportion of a solute in a certain quantity of solution, and it is displayed as a percentage. To calculate the mass percent, we use the formula:

Mass Percent = (mass of solute/mass of solution) * 100

If, for example, you have a solution composed of 20g of sugar in 180g of water, the mass of the solution would be the sum of these two (200g), and thus the mass percent of sugar in the solution is (20/200)*100 = 10%.

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Answer:

61kg

Explanation:

Like all other hydrocarbons, the combustion of propane will yield water and carbon iv oxide.

Let’s write a complete and balanced chemical equation for this.

C3H8(g) + 5O2(g) → 3CO2(g) + 4H2O(l)

Now, we first convert the information into a mass.

We know that mass = density * volume

Let’s convert the volume here into ml since density is in mL. It must be remembered that 1000ml = 1L. Hence, 29.4L = 29,400ml

The mass is thus = 0.6921 * 29,400 = 20,347.74g

Now from the balanced equation, we can see that one mole of propane produced 3 moles of carbon iv oxide. This is the theoretical relation.

Let’s now calculate the actual number of moles. The number of moles of propane produced is the mass of propane divided by the molar mass of propane. The molar mass of propane is 3(12) + 8(1) = 36 + 8 = 44g/mol

The number of moles = 20,347.74/44 = 462.44

We simply multiply this number by 3 to get the actual number of moles of carbon dioxide produced. This is equals 1387.35 moles

Since we know this, we now calculate the mass of carbon iv oxide produced. The mass is equals the number of moles multiplied by the molar mass. The molar mass of carbon iv oxide is 44g/mol.

The mass produced is thus 1387.35 * 44 = 61,043g

To get the kilogram equivalent, we simply divide by 1000 = 61,043/1000 = 61kg

Answer:

ΔH of reaction is -147 kJ/mol

Explanation:

For the reaction:

CH₄(g) + X₂(g) → CH₃X(g) + HX(g)

It is possible to obtain ΔHr of reaction from the sum of ΔH of products minus ΔH of reactants:

ΔHr = ΔH CH₃X + ΔH HX - (ΔH CH₄ + ΔH X₂) (1)

The ΔH of each compound is obtained from bond energies thus:

ΔH CH₃X = 3×C-H + C-X = 3×416 kJ/mol + 222 kJ/mol = 1470 kJ/mol

ΔH HX = H-X = 277 kJ/mol

ΔH CH₄ = 4×C-H = 4×416kJ/mol = 1664 kJ/mol

ΔH X₂ = X-X = 230 kJ/mol

Replacing in (1):

ΔHr = 1470 kJ/mol + 277kJ/mol - (1664 kJ/mol + 230 kJ/mol) = -147 kJ/mol

I hope it helps!

Final answer:

To calculate the enthalpy change for CH₄ + X₂ → CH₃X + HX, we tally the energy needed to break one C-H bond and one X-X bond (total 646 kJ/mol) and subtract the energy released from forming one C-X bond and one H-X bond (total 499 kJ/mol), resulting in a ΔH of 147 kJ/mol.

Explanation:

To calculate the enthalpy change (ΔH) for the reaction CH₄(g) + X₂(g) → CH₃X(g) + HX(g), we need to consider the bond energies provided. The calculation involves computing the energy required to break bonds in the reactants and the energy released from forming bonds in the products.

First, we break one C-H bond in CH₄ and one X-X bond. The energy required is:

1 mol C-H: 416 kJ/mol

1 mol X-X: 230 kJ/mol

When these connections are broken, the total energy needed is:

416 kJ/mol + 230 kJ/mol = 646 kJ/mol

Next, we form one C-X bond and one H-X bond with the energies released as follows:

1 mol C-X: 222 kJ/mol

1 mol H-X: 277 kJ/mol

The total energy released in forming these bonds is:

222 kJ/mol + 277 kJ/mol = 499 kJ/mol

The enthalpy change of the reaction is the energy required minus the energy released:

ΔH = 646 kJ/mol - 499 kJ/mol = 147 kJ/mol

This reaction is endothermic, as indicated by the positive value of ΔH.

Answer:

1)20. ML at 100.°C

Explanation:

Average kinetic energy is not related with volume.  so increase in temperature will also increase kinetic energy. so this increase means the highest temperature will be a right answer.

Final answer:

The water sample with the highest average kinetic energy is the 20 mL of water at 100.0°C, as average kinetic energy is directly proportional to temperature.

Explanation:

The molecules with the highest average kinetic energy are in the sample of water at the highest temperature. Kinetic energy is directly proportional to the absolute temperature of the substance, meaning that as temperature increases, kinetic energy also increases. Therefore, ignoring the volume of the water samples, the rank from highest kinetic energy to lowest based on temperature would be:

The sample at 100.0°C holds the highest average kinetic energy because it has the highest temperature.

Answer: highest activity of salivary amylase is at pH 6.8.

Explanation:Amylase enzyme catalyses the hydrolysis of starch into sugars. Amylase is present in the saliva of humans and some other mammals. The enzymatic activity of salivary amylase ranges from 6 to 7. Above and below this range, the reaction rate reduces as enzymes get denaturated. But the optimum enzymatic activity is at pH 6.8.

Answer:

Ionic compound.

Explanation:

Ionic bond:

It is the bond which is formed by the transfer of electron from one atom to the atom of another element. the electrostatic attraction is created between bonded atoms.  

Both bonded atoms have very large electronegativity difference. The atom with large electronegativity value accept the electron from other with smaller value of electronegativity.

The compound having ionic bonds generally have moderate to high boiling points and melting point because of greater electrostatic interaction. Their electrical conductivity are high and these minerals tend to dissolve in water.

For example:

Sodium chloride is ionic compound. The electronegativity of chlorine is 3.16 and for sodium is 0.93. There is large difference is present. That's why electron from sodium is transfer to the chlorine. Sodium becomes positive and chlorine becomes negative ion and  both atoms joint together through electrostatic interaction.

Answer:

The substance has a specific heat of 1.176 J/g°C

Explanation:

Step 1: Data given

Temperature change = 34 °C

Mass of the substance = 20 kg = 20000 grams

The substance gained 800 kJ of heat during this temperature change

Step 2: Calculate the specific heat

q = m*c*ΔT

⇒ with q = heat gained = 800 kJ = 800000 J

⇒ with m = the mass of the substance = 20 kg = 20000 grams

⇒ with c = the specific heat of the substance = TO BE DETERMINED

⇒ with ΔT = the change of temperature = T2 -T1 = 48° - 14 ° = 34°

c = q/(m*ΔT)

c = 800000 / (20000 * 34)

c = 1.176 J/g°C

The substance has a specific heat of 1.176 J/g°C

Answer:

The catabolic process of converting carbohydrates to CO2 requires oxidation of carbon.

Explanation:

There are multiple definitions of reduction-oxidation. There is one that explains it with respect to oxygen, the other with respect to hydrogen and another with respect to electrons. The relevant one here is the one that explains it in terms of hydrogen. Oxidation is the removal of hydrogen while reduction is the addition of hydrogen. During repiration, the carbon loses the hydrogens attached to it and is therefore oxidized. These hydrogens attach themselves to oxygen which means oxygen is reduced.

Answer:

The correct answer is option C.

Explanation:

Ionic bond is defined as the bond which is formed by complete transfer of electrons from one atom to another atom.

Ionic compound is formed by the complete transfer of electrons from 1 atom to another atom. The cation is formed by the loss of electrons by metals and anions are formed by gain of electrons by non metals.

From the given options , the option with metal and non metal is potassium and chlorine. these elements will combine together to form ionic compound called potassium chloride.

Answer: Option (D) is the correct answer.

Explanation:

A reaction in which heat energy is absorbed by the molecules of a substance is known as an endothermic reaction.

Whereas when energy is released by the molecules of a substance in a reaction then it is known as an exothermic reaction.

Thus, we can conclude that the vaporization of rubbing alcohol is endothermic.

Among the provided options, the vaporization of rubbing alcohol is the endothermic process, as it involves the absorption of heat from its surroundings.

In the context of chemistry, an endothermic process is one in which heat is absorbed from the surroundings. This results in an overall increase in the internal energy of the system. Given the options, the vaporization of rubbing alcohol is the process that is endothermic. This is because when rubbing alcohol vaporizes, it absorbs heat from its surroundings, causing the surrounding environment to feel cooler. Other examples might be the melting of ice or the evaporation of water, both of which require an external heat source to facilitate the process.

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Answer:

The identity of the gas is Cl₂ (chlorine)

Explanation:

STP conditions are:

1 atm → Pressure

273.15 K → T°

So, we must use the Ideal Gas Law to get the moles.

Before that, we will think density as data where 3.164 g of diatomic gas are contained in 1 L of volume.

P.V = n . R . T

1 atm . 1 L = n. 0.082 L.atm/mol.K . 273.15K

1 L.atm / (0.082 L.atm/mol.K . 273.15K) = n

0.0446 mol = n

This quantity of diatomic gas, are 3.164 g so the molar mass will be:

Mass / mol = molar mass

3.164 g / 0.0446 mol = 70.9 g/m

The element (a diatomic molecule), which has that molar mass in the periodic table is the Cl₂.

1 Cl = 35.45 g/m

Cl₂. = 70.9 g/m

Using the density data and Avogadro's principle, we can calculate the molar mass of the unknown gas to be around 70.8 g/mole. Yet, none of the gases from the provided list align with this molar mass.

The identity of the unknown diatomic gas can be found using the Ideal Gas Law and Avogadro's principle. Avogadro's principle states that equal volumes of gases at the same temperature and pressure will contain an equal number of particles (or moles). Hence, at Standard Temperature and Pressure (STP), 1 mole of any gas will occupy 22.4 L.

From the data provided, we know that 1 mole of the unknown gas has a mass of 3.164 g/L × 22.4 L per mole = 70.8 g/mole. Among the different potential gases listed in the reference, O₂ is a diatomic gas and has a molar mass of 32g/mole, which isn't close to the calculated one. NH3 has a molar mass of 17g/mole which also doesn't match. This leaves us with He (Helium), which is not diatomic and hence can't be our gas. We can therefore confidently conclude that there seems to be a mistake as none of the gases listed align with our calculated molar mass.

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Answer:

MW = 94.07 g/mol

Explanation:

We are here given a neutralization reaction which is a 1: 1 molar relation. So calculating the # mol NaOH reacted we will know the  #mol of  the monoprotic acid, and since we are given the mass of sample we can calculate the molar mas of the compund because # mol = mass/ MW .

# mol NaOH = 0.0823 mol/L x 33 mL/1000 mL/L = 0.0027 mol

# mol = m/MW ∴   MW: m/# mol

MW :  0.254 g / 0.0027 mol =  94.07 g/mol

Answer: A. There are more reactants than products at equilibrium.

Explanation:

Equilibrium constant is defined as the ratio of concentration of products to the concentration of reactants each raised to the power their stoichiometric ratios. It is expressed as [tex]K_{eq}[/tex]

For a general chemical reaction:

[tex]aA+bB\rightarrow cC+dD[/tex]

The expression for [tex]K_{eq}[/tex] is written as:

[tex]K_{eq}=\frac{[C]^c[D]^d}{[A]^a[B]^b}[/tex]

There are 3 conditions:

When [tex]K_{eq}>1[/tex]; the reaction is product favored.

When [tex]K_{eq}<1[/tex]; the reaction is reactant favored.

When [tex]K_{eq}=1[/tex]; the reaction is in equilibrium.

From the above expression, the equilirbium constant is directly dependent on product concentration. Thus, more is the concentration of product, more will be the equilibrium constant.

The values of [tex]K_{eq}[/tex] less than 1 , means the reactant are more than the products.

Answer:

Explanation:

Newton's first law of motion :

"Every object persists in its state of rest or uniform motion in a straight line unless it is compelled to change that state by forces exerted on it."

From the question we know that the net forces on the object were zero or that the there were no unbalanced forces on it.

Therefore we can assume that the object is moving along a straight line.

And the object was moving at a constant speed of 30 mph.

So it is clear from the Newton's first law that the object will remain in the state of motion as it was earlier.

That is the object will remain in motion at constant speed of 30 mph.

Answer:

See explanation below

Explanation:

a) According to this, this is an excercise that is involving a separation and reaction of different compounds. The n-butyl bromide is formed when, you made the following reaction:

CH2 = CH - CH2 - CH3 + HBr/peroxide -----------> Br - CH2 - CH2 - CH2 - CH3

Now, in this reaction, we still has traces of HBr in the product, so, in order to neutralize these traces, we wash the solution with bicarbonate sodium forming sodium bromide and carbonic acid as follow:

HBr + Na2CO3 ---------> NaBr + Na2CO3

Also, this is a weak base so it will not react with the n-butylbromide to form another product.

b) Basing of what it was stated above, we cannot wash the solution with NaOH because this is a strong base, and not only wil eliminate the traces of HBr, it will also react with the butylbromide causing an elimination and substitution reaction, giving the following products:

BrCH2CH2CH2CH3 + NaOH --->CH2=CHCH2CH3 + OHCH2CH2CH2CH3

That it's why we need to wash this product with a weak base only.

c) The density of 1-chlorobutane is 0.88 g/mL, density of water is 1 g/mL and density of sodium bicarbonate is 2.2 g/cm3, therefore, the one that has a greater density will go at the lower phase.

In this case, after the reflux, it will stay in the lower phase.

after adding water, it will be in the upper phase.

after adding bicarbonate, it will be in the upper phase too.

a. The purpose of washing the crude n-butyl bromide with aqueous sodium bicarbonate is to remove acidic impurities. b. It would be undesirable to wash the crude halide with aqueous sodium hydroxide. After each stage of the separation procedure, the alkyl chloride would appear as the upper or lower phase.

a. The purpose of washing the crude n-butyl bromide with aqueous sodium bicarbonate is to remove any acidic impurities. Sodium bicarbonate is a weak base that reacts with acidic impurities, such as hydrochloric acid or sulfuric acid, to form water-soluble salts. The balanced chemical equation for the reaction between sodium bicarbonate and hydrochloric acid is:

NaHCO3 + HCl → NaCl + H2O + CO2

b. It would be undesirable to wash the crude halide with aqueous sodium hydroxide because sodium hydroxide is a strong base that can react with the bromide ion to form sodium bromide, which would not be easily separated from the organic layer.

After the reflux, the alkyl chloride would appear as the upper phase. After the addition of water, the alkyl chloride would still appear as the upper phase. After the addition of sodium bicarbonate, the alkyl chloride would appear as the lower phase.

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Answer:

H⁺/H₂//Ni/Ni⁺²; H⁺/H₂//Cd/Cd⁺²; Ni⁺²/Ni//Cd/Cd⁺²

Explanation:

The redox reactions are spontaneously when the E° of the substance that is reduced is higher than the E° of the substance that is oxidized. The substance is reduced when gaining electrons and is oxidized when loses electrons.

So, the reactions that occur spontaneously are:

2H⁺ + Ni → H₂ + Ni⁺² (H⁺ is reduced and Ni is oxidized)

2H⁺ + Cd → H₂ + Cd⁺² (H⁺ is reduced and Cd is oxidized)

Ni⁺² + Cd → Ni + Cd⁺² (Ni⁺² is reduced and Cd is oxidized)

Pairs: H⁺/H₂//Ni/Ni⁺²; H⁺/H₂//Cd/Cd⁺²; Ni⁺²/Ni//Cd/Cd⁺²

Answer:

C) H⁺

Explanation:

When we are balancing the reaction in an acid medium, hydrogen is balanced using the H⁺ species. This is most likely the intended answer of your question.

When the reaction takes place not in an acid medium, but in an alkaline one, then hydrogen is present as the OH⁻ species. However this option is not given in your question.

Thus the answer is option C).

Answer:

2 51 × 10^-5mol/L

Explanation:

The concentration of hydrogen ions can be calculated using the formula below :

pH = -log [H+]

pH = 4.6

[H+] = ?

[H+] = Antilog (-4.6)

[H+] = 2 51 × 10^-5mol/L

Answer: The molecular formula for the compound is [tex]C_6H_6[/tex]

Explanation:

We are given:

Percentage of C = 92.26 %

Percentage of H = 7.74 %

Let the mass of compound be 100 g. So, percentages given are taken as mass.

Mass of C = 92.26 g

Mass of H = 7.74 g

To formulate the empirical formula, we need to follow some steps:

Moles of Carbon =[tex]\frac{\text{Given mass of Carbon}}{\text{Molar mass of Carbon}}=\frac{92.26g}{12g/mole}=7.68moles[/tex]

Moles of Hydrogen = [tex]\frac{\text{Given mass of Hydrogen}}{\text{Molar mass of Hydrogen}}=\frac{7.74g}{1g/mole}=7.74moles[/tex]

For the mole ratio, we divide each value of the moles by the smallest number of moles calculated which is 7.68 moles.

For Carbon = [tex]\frac{7.68}{7.68}=1[/tex]

For Hydrogen = [tex]\frac{7.74}{7.68}=1[/tex]

The ratio of C : H = 1 : 1

The empirical formula for the given compound is [tex]CH[/tex]

To calculate the molecular mass, we use the equation given by ideal gas equation:

PV = nRT

Or,

[tex]PV=\frac{m}{M}RT[/tex]

where,

P = pressure of the gas = 820 torr

V = Volume of gas = 250 mL = 0.250 L  (Conversion factor:  1 L = 1000 mL )

m = mass of gas = 0.6883 g

M = Molar mass of gas = ?

R = Gas constant = [tex]62.3637\text{ L. torr }mol^{-1}K^{-1}[/tex]

T = temperature of the gas = [tex]100^oC=(100+273)K=373K[/tex]

Putting values in above equation, we get:

[tex]820torr\times 0.250L=\frac{0.6883g}{M}\times 62.3637\text{ L torr }mol^{-1}K^{-1}\times 373K\\\\M=\frac{0.6883\times 62.3637\times 373}{820\times 0.250}=78.10g/mol[/tex]

For determining the molecular formula, we need to determine the valency which is multiplied by each element to get the molecular formula.

The equation used to calculate the valency is:

[tex]n=\frac{\text{Molecular mass}}{\text{Empirical mass}}[/tex]

We are given:

Mass of molecular formula = 78.10 g/mol

Mass of empirical formula = 13 g/mol

Putting values in above equation, we get:

[tex]n=\frac{78.10g/mol}{13g/mol}=6[/tex]

Multiplying this valency by the subscript of every element of empirical formula, we get:

[tex]C_{(1\times 6)}H_{(1\times 6)}=C_6H_6[/tex]

Hence, the molecular formula for the compound is [tex]C_6H_6[/tex]

Answer:

It can be removed by acidic chemicals

Explanation:

The glue likely consists of compounds with nonpolar covalent bonds that repel water but are dissolved by solvents like acetone, explaining why water can't remove the glue but fingernail polish remover can.

The observation that glue does not easily wash off with water but can be removed with a substance like fingernail polish remover helps us understand the chemical composition of the glue. The adhesive used in the glue is likely a combination of compounds with nonpolar covalent bonds. These compounds resist polarity, which repels water molecules. However, they can be dissolved with certain solvents that contain similar nonpolar substances, such as acetone found in fingernail polish remover. Acetone, or dimethyl ketone, is used as a solvent in various applications due to its ability to dissolve many substances.

By understanding the chemical reactions between different substances, one can often predict their behaviors when they interact. In this case, the interaction between the glue and the water or acetone is predictable based on our understanding of their individual chemical compositions and the forces of cohesion and adhesion that influence how substances combine.

For example, when substances such as water, which have molecules with polar covalent bonds, interact with substances like glue, which has molecules with nonpolar covalent bonds, cohesion within the water molecules causes them to resist mixing with the glue molecules. Conversely, adhesion between the glue molecules and the acetone molecules in fingernail polish remover allows them to mix effectively, thereby enabling the acetone to dissolve the glue.

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Answer: The atomic number of an element is the same as the number of its protons.

Explanation: For example, the atomic number of oxygen is 8. So, this would mean that the number of protons would be 8.

Hope this helps^

To find the final pressure of the gas mixture after transferring the gases, we can use the ideal gas law equation. The final pressure is calculated based on the total number of moles of gas and the final volume of the container. The final pressure of the gas mixture is 0.229 atm.

To find the final pressure of the gas mixture after the transfer, we can use the ideal gas law equation, which states that PV = nRT, where P is the pressure, V is the volume, n is the number of moles, R is the ideal gas constant, and T is the temperature.

We can calculate the number of moles of N2 gas using the information given:

n = PV/RT = (5.23 atm)(1.20 L)/(0.0821 atm·L/mol·K)(26 + 273 K) = 0.287 mol

Similarly, we can calculate the number of moles of O2 gas:

n = PV/RT = (5.21 atm)(5.10 L)/(0.0821 atm·L/mol·K)(26 + 273 K) = 1.05 mol

To find the final pressure, we need to find the total number of moles of gas and the final volume of the container:

Total moles of gas = moles of N2 + moles of O2 = 0.287 mol + 1.05 mol = 1.34 mol

Final volume of the container = sum of the initial volumes = 1.20 L + 14.5 L = 15.7 L

Now we can use the ideal gas law again to calculate the final pressure:

P = nRT/V = (1.34 mol)(0.0821 atm·L/mol·K)(20 + 273 K)/(15.7 L) = 0.229 atm

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