Bond energies do not account for the energy associated with the formation of aqueous solutions. Explain what energy is not accounted for AND how this energy contributes to the difference in calculated ∆Hrxn values using ∆Hf versus bond energy data ( -524 kJ/mol bond energy and -162.59 kJ/mol ∆Hf)

The pH after the addition of 81 mL of 0.40 M NaOH to 80.0 mL of 0.40 M HClO4 is 13.30

The balanced chemical equation for the reaction between HClO4 and NaOH is:

HClO4 + NaOH → NaClO4 + H2O

First, let's find the moles of HClO4 and NaOH present before the reaction:

moles HClO4 = 0.40 mol/L x 0.080 L = 0.032 mol

moles NaOH = 0.40 mol/L x 0.081 L = 0.0324 mol

Since the moles of NaOH added are greater than the moles of HClO4 initially present, NaOH is the limiting reagent. Therefore, all of the NaOH will react with the HClO4, and we need to find the number of moles of HClO4 that react with the NaOH.

According to the balanced equation, 1 mole of NaOH reacts with 1 mole of HClO4. Therefore, 0.0324 mol of HClO4 will react with the 0.0324 mol of NaOH.

The remaining moles of HClO4 after the reaction is given by:

moles HClO4 remaining = 0.032 mol - 0.0324 mol = -0.0004 mol

Since the resulting moles of HClO4 is negative, this means that all the HClO4 has been used up and the solution is basic. The excess NaOH reacts with water to produce hydroxide ions:

NaOH + H2O → Na+ + OH- + H2O

The total volume of the solution after the reaction is:

V = 80.0 mL + 81 mL = 0.161 L

The concentration of OH- ions produced is given by:

[OH-] = moles NaOH / V = 0.0324 mol / 0.161 L = 0.201 M

Using the expression for the ion product of water, we can calculate the concentration of H+ ions:

Kw = [H+][OH-] = 1.0 x 10^-14

[H+] = Kw / [OH-] = 1.0 x 10^-14 / 0.201 M = 4.975 x 10^-14

The pH of the solution is given by:

pH = -log[H+] = -log(4.975 x 10^-14) = 13.30

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The fair test that he could do to answer the question is C. Try to scratch the marble with each of the minerals, and group the minerals that do scratch the marble together.

When he try to scratch the marble with each of the minerals in her group he can observe the results for a fair test. however One that scratches the other is harder than one that has been scratched.

Hence, Given that marble is a well-known mineral, any mineral that scratches it is harder, while those that do not are less so. and the hardness of minerals can be determined using  with the Moh's scale, with diamond being the hardest mineral and talc being the least hard.

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complete question;

Lewis has the collection of minerals shown in the picture below.He knows that a harder mineral will scratch a softer mineral. He wants to design an experiment that will answer the following question:

Which of the minerals in the collection have a greater hardness than a rock made of marble?

Which of these is a fair test that he could do to answer the question?

A.

Separate the minerals into light and dark colors, and then try to scratch the marble with the light colored minerals.

B.

Separate the minerals into ones that feel heavier and lighter, and then try to scratch the marble with the heavy minerals.

C.

Try to scratch the marble with each of the minerals, and group the minerals that do scratch the marble together.

D.

Try to scratch the pink quartz with each of the minerals, and group the minerals that do not scratch the pink quartz together.

Answer:

See Explanation

Explanation:

In discussing the reason why Et₃SiCl is more easily hydrolysed than Et₃CCl, we must remember that the electronegativity difference between silicon and chlorine is much higher than the electronegativity difference between carbon and chlorine.

As a result of this, the Si-Cl bond in Et₃SiCl is more polar and hence susceptible to attack by water than the C-Cl bond in Et₃CCl.

Also, it is postulated that the presence of vacant d orbitals on silicon assists hydrolysis in Et₃SiCl. Such vacant orbitals are absent in carbon hence Et₃CCl does not undergo hydrolysis.

The reaction scheme is shown in the image attached to this answer.

A chemical reaction's change in enthalpy is equal to the  ∆hf0 of products minus ∆hf0 of reactants.

Chemists can determine how much energy is consumed or created in a chemical process by measuring the change in enthalpy.

A reaction is exothermic, or one that generates heat in the environment, if the change in enthalpy is negative (i.e. 0).

The reaction is endothermic, meaning that it absorbs heat from the environment, if the change in enthalpy is positive (i.e. > 0).

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The complete question is

Using a table that lists standard heats of formation, you can calculate the change in enthalpy for a given chemical reaction. the change in enthalpy is equal to _____.

a)  ∆hf0 of reactants minus ∆hf0 of products

b) ∆hf0 of products plus ∆hf0 of reactants

c)  ∆hf0 of products divided by ∆hf0 of reactants

d)  ∆hf0 of products minus ∆hf0 of reactants

The fair use principle would cover Ms. Green's use of Mr. Blue's chapter photocopy for her class discussion.

Under certain conditions, such as for educational purposes, the legal principle of fair use permits the limited use of copyrighted content without the requirement for prior consent from the copyright owner.

The four criteria that establish whether a use of a copyrighted work is fair use are the use's intent and character, the copyrighted work's nature, the quantity and quality of the portion used, and the impact of the use on the copyrighted work's potential market or value. The use made by Ms. Green would probably be regarded as transformative, constrained, and not intended to undermine the market for the original work, meeting the requirements for fair use.

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1. The buoyant force on the beachball is 5N.

2. The mass of the chair is 6370 grams.

3. The  volume of the copper sphere is 53.88 cm³

Mass is described as the quantity of matter in a physical body. It is also a measure of the body's inertia, the resistance to acceleration when a net force is applied.

Archimedes' principle states that An object immersed in a fluid experiences a buoyant force that is equal in magnitude to the force of gravity on the displaced fluid

According to Archimedes principle, the buoyant force acting on the beach ball equals the weight of the water displaced by the beachball. So we can say the buoyant force is 5N.

We have that density = mass/ volume

So the mass of the chair will be density* volume

mass= 9800 * 0.650

mass=  6370 grams

The volume of the copper sphere will be

volume= mass/ density

volume = 2.5/ 0.0464 cm³

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Answer:

D

Explanation:

molecules have potential energy and kinetic energy.

Tempreture is defined as the average kinetic energy and internal energy is PE+KE. Pptential energy in particles or molecules is just there position relative to one another. A gas which has seperated particles will have a greater potential energy than a solid/liquid.

Answer:

Bobcats are consumers of marmots and grouses

Explanation:

\(C6H_14\)is the molecular formula for Hexane, a hydrocarbon. The correct model for \(C6H_14\) is D. Option D is correct answer.

/\/\/\/:Hexane (\(C6H_14\)) is an alkane with a chain of six carbon atoms, having 14 hydrogen atoms. The bond angles of carbon atoms in hexane are 109.5 degrees, and carbon atoms in hexane have a tetrahedral geometry. The representation of a molecule in a model helps to visualize the 3D structure of the molecule. A simple way to represent the 3D structure of hexane is by using the wedge-and-dash notation. In this notation, solid wedges represent bonds coming out of the plane of the paper towards us, and dashed lines represent bonds going back into the plane of the paper away from us. Using this notation, the correct model of hexane (\(C6H_14\)) would be D. /\/\/\/.

The correct option is D.

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The equilibrium constant for the system at the given temperature is 1.1×10⁻⁵

Equilibrium constant for a given is defined as the concentration of the products raised to their coefficient to the concentration of the reactants raised to their coefficient

For example:

eB <=> cD

The equilibrium constant for the reaction above is given as

Ke = [D]^c / [B]^e

The equilibrium constant for the reaction reaction can be obtained as follow

Ke = [NO]² / [N₂][O₂]

Ke = [1.1×10⁻⁵]² / [6.4×10⁻³][1.7×10⁻³]

Ke = 1.1×10⁻⁵

Thus, the equilibrium constant for the reaction at the given temperature is 1.1×10⁻⁵

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Complete question

See attached photo

Answer: SnO2 + 2 H2 = Sn + 2 H2O

Explanation: I used a balance equation website. It's called WebQC if you want to check it out for future help.

The empirical formulas for at least four binary ionic compounds that can be formed from the given ions are as follows: CaF2, CaS, PbF4, and PbS2.

A binary ionic compound is made up of ions from two different elements: one metal and one nonmetal. Iron(III) iodide, FeI3, for example, is made up of iron ions, Fe3+ (elemental iron is a metal), but also iodide ions, I- (elemental iodine is a nonmetal).

The positive ion (cation) has been written first in the name, followed by the negative ion (anion). The cation has the same name as the (neutral metal) element that it is derived. The charge on the cation is denoted by a Roman numeral within parentheses immediately following the cation's name (e.g., Fe3+ = "iron(III)", Fe2+ = "iron(II)"). The anion is named by prefixing the root of (nonmetal) element name with the suffix -ide

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Explanation:

Polar molecules or liquid are formed whenever the electronegativity separations of the bound atoms changes. Because once sharing of electrons equally between atoms in a diatomic molecule or even when polar bonds in a complex mixture cancel one another out, nonpolar compounds or liquid form.

Answer:

D

Explanation:

Reduction refers to gain in electrons. Hence it is D

Oxidation occurs when the element loses electrons. Hence A is wrong

Synthesis reaction

It is a reaction in which 2 or more reactants combine with each other to form one product .

Check option C

Sulphate and water are combining to form sulfuric acid .

Hence option C is correct

Answer:

SO3 + H2O => H2SO4

Explanation:

I took the test :)

Complete the table to show the fraction of a radioisotope left after each half-life has passed:

Number of half-lives 0 1 2 3 4 5 6

Fraction remaining 1 1/2 1/4 1/8 1/16 1/32 1/64

Use the table above to help you answer the questions below:

a) After 5 half-lives, the fraction remaining is 1/32 or 0.03125. To find the percentage remaining, multiply by 100:

0.03125 x 100 = 3.125%

Therefore, after 5 half-lives, 3.125% of the sample will remain.

b) After 4 half-lives, the fraction remaining is 1/16 or 0.0625.

c) To find out how many half-lives it will take for 25% of a sample to remain, you can set up an equation:

\((1/2)^{(n)} = 0.25\)

where n is the number of half-lives.

Taking the logarithm of both sides gives:

n x log(1/2) = log(0.25)

n = log(0.25) / log(1/2)

n = 2.

Therefore, it will take 2 half-lives for 25% of the sample to remain.

d) After 3 half-lives, the fraction remaining is 1/8 or 0.125. To find the percentage remaining, multiply by 100:

0.125 x 100 = 12.5%

Therefore, after 3 half-lives, 12.5% of the sample will remain.

e) The fraction remaining after 8 half-lives is \((1/2)^8\), which simplifies to 1/256.

The half-life of iodine-131 is 10 days.

After 30 days, three half-lives have passed:

\((1/2)^3 = 1/8\)

Therefore, after 30 days, 1/8 or 0.125 of the original mass will remain:

0.125 x 15g = 1.875g

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Answer:

6 mol

Explanation:

Discussion

The answer is very nearly six. I will use rounded whole numbers to get the molar mass. Every periodic table is different so you will have to redo my numbers using your periodic table.

The trick is to find 1 mole of CH4 and divide that into 96.

Givens

96.0 grams of CH4

Solution

Find 1 mol of CH4

1 * 1C = 1 * 12 = 12 grams of Carbon in 1 mol of CH4

4 * H = 4 * 1 = 4 grams of Hydrogen in 1 mol of CH4

Total = 16 grams of C and H in 1 mol of CH4

Find 96 grams in mols.

Formula

mol = given mass / molar mass

given mass = 96 grams

molar mass = 16 grams

Mol = 96 / 16

Answer: mol = 6

A condensed structural formula is a simple way of representing organic compounds.

The given organic compounds and condensed structural formula is presented below;

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This can be solved according to Le C ha.tellors principle

So

Here to increase NO_2

We need to increase the temperature or increase the concentrations of reactants

The addition of N₂O₄(g) to the system would result in an increase of nitrogen dioxide, NO₂.

The balanced equation provided shows the equilibrium between nitrogen dioxide (NO₂) and dinitrogen tetroxide (N₂O₄). According to Le Chatelier's principle, a change in conditions will cause the system to shift in a way that opposes the change. In this case, if N₂O₄ is added to the system, the equilibrium will shift to the right to consume the added N₂O₄ and produce more NO₂.

Based on the given information, the enthalpy change (AH°) for the reaction is 58 kJ. This indicates that the forward reaction (from N₂O₄ to 2NO₂) is endothermic, meaning it requires heat to proceed. Adding N₂O₄ to the system will provide more reactant molecules, increasing the concentration of N₂O₄ and causing the equilibrium to shift towards the products (more NO₂) to minimize the effect of the added N₂O₄.

Therefore, the addition of N₂O₄ to the system will result in an increase in nitrogen dioxide, NO₂, as the equilibrium shifts to the right to restore equilibrium.

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Answer:

animal cells would because of the vacuole

Combustion can be defined as the reaction of a compound with oxygen. The enthalpy of combustion of octane is \(\Delta H_{\rm rxn}\) for \(\rm C_8H_{18}\;+\;25\;O_2\;\rightarrow 8\;CO_2\;+\;9\;H_2O\).

The enthalpy of reaction is the amount of heat energy absorbed or lost by the molecules in the chemical reaction.

The enthalpy of combustion is the amount of heat energy released by the compound in the reaction with oxygen.

The reaction in which heat is liberated with the reaction of a compound with oxygen has an enthalpy of combustion, equivalent to the enthalpy of reaction.

The combustion of octane can be given as:

\(\rm C_8H_{18}\;+\;25\;O_2\;\rightarrow 8\;CO_2\;+\;9\;H_2O\)

Thus, the reaction has combustion energy equivalent to the enthalpy of the reaction is \(\rm C_8H_{18}\;+\;25\;O_2\;\rightarrow 8\;CO_2\;+\;9\;H_2O\). Thus, option B is correct.

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Answer:

170 mL

Explanation:

The total volume to be reported should be 170 mL.

According to the significant rule in mathematical operations, final answers are usually reported to reflect the accuracy of the least accurate number.

In this case, the least accurate of all the volumes has zero significant digits after the decimal, hence, the final answer after the mathematical operation should also have no significant digits after the decimal.

           18 + 128.7 + 23.45 = 170.15

Therefore, the total volume to be reported when significant digits are taken into account would be 170 mL.

The molar hydroxide ion concentration in the given aqueous solution is 4.0 x 10⁻⁸ M.

To find the molar hydroxide ion concentration, we will use the concept of the ion product constant of water (Kw) and the provided hydrogen ion concentration [H+].

The ion product constant of water, Kw, is given by the product of the hydrogen ion concentration [H+] and hydroxide ion concentration [OH-]. In pure water at 25°C, Kw is 1.0 x 10⁻¹⁴. The formula is:

Kw = [H+] × [OH-]

We are given [H+] = 2.5 x 10⁻⁷. We can now find the [OH-] concentration using the formula:

[OH-] = Kw / [H+]

Plug in the values:

[OH-] = (1.0 x 10^-14) / (2.5 x 10⁻⁷)

[OH-] = 4.0 x 10⁻⁸

This calculation is based on the relationship between the ion product constant of water and the concentrations of hydrogen and hydroxide ions.

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Answer:

color

Explanation:

The effective temperature is directly related to the color of the star: the higher the temperature, the bluer the light emitted by the star.

Answer:

~441.8mmHg

Explanation:

Use Gay-Lussac's law;

(P1/T1)=(P2/T2)

P1=418mmHg

T1=298K

P2=?

T2=315K

From the equation above, we can derive the equation for P2.

So, P2=(P1 x T2)/(T1)

          =(418 x 315)/(298)

          ~441.8mmHg

Hope it helps:)

Answer:

441.8mmHg

Explanation:

The quantity of Ba(OH)2 that Cal needs to add to reach the equivalence point is 26.6 mL.

To determine how many mL of Ba(OH)2 Cal needs to add to reach the equivalence point, we first need to determine the balanced chemical equation for the reaction between HBr and Ba(OH)2:

2HBr + Ba(OH)2 → 2H2O + BaBr2

From this equation, we can see that the stoichiometric ratio of HBr to Ba(OH)2 is 2:1. This means that for every 2 moles of HBr, we need 1 mole of Ba(OH)2 to completely react.

To find the number of moles of HBr in 55.6 mL of 0.342 M solution, we use the equation:

moles HBr = concentration x volume
moles HBr = 0.342 M x 0.0556 L
moles HBr = 0.019 moles

Since the stoichiometric ratio of HBr to Ba(OH)2 is 2:1, we need half as many moles of Ba(OH)2 to reach the equivalence point. Therefore, we need:

moles Ba(OH)2 = 0.019 moles / 2
moles Ba(OH)2 = 0.0095 moles

To find the volume of 0.357 M Ba(OH)2 solution needed to provide 0.0095 moles, we use the equation:

moles Ba(OH)2 = concentration x volume
0.0095 moles = 0.357 M x volume
volume = 0.0095 moles / 0.357 M
volume = 0.0266 L or 26.6 mL

Therefore, Cal needs to add 26.6 mL of 0.357 M Ba(OH)2 solution to reach the equivalence point.

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