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Answer:

ΔH°rxn = -780kJ

Explanation:

It is possible to find enthalpy change of a reaction by the sum of analogue reactions (Hess's law).

Using the reactions:

1. 2Al(s) + 3/2O2(g) → Al2O3(s)  ΔH°rxn = −1601 kJ/mol

2. 2Fe(s) + 3/2O2(g) → Fe2O3(s)  ΔH°rxn = −821 kJ/mol

1 - 2:

2Al(s) + Fe2O3(s) → Al2O3(s) + 2Fe(s)

ΔH°rxn = ΔH°rxn(1) - ΔH°rxn(2)

ΔH°rxn = −1601 kJ/mol - (-821 kJ/mol)

ΔH°rxn = -780kJ

Considering the Hess's Law, the enthalpy change for the reaction is -780 kJ.

Hess's Law indicates that the enthalpy change in a chemical reaction will be the same whether it occurs in a single stage or in several stages. That is, the sum of the ∆H of each stage of the reaction will give us a value equal to the ∆H of the reaction when it occurs in a single stage.

In this case you want to calculate the enthalpy change of:

2 Al(s) + Fe₂O₃(s) → 2 Fe(s) + Al₂O₃(s)

which occurs in two stages.

You know the following reactions, with their corresponding enthalpies:

Equation 1:  2 Al(s) + [tex]\frac{3}{2}[/tex] O₂(g) → Al₂O₃(s)      ΔH = −1601 kJ/mol  

Equation 2:  2 Fe(s) + [tex]\frac{3}{2}[/tex] O₂(g) → Fe₂O₃(s)      ΔH = −821 kJ/mol

Because of the way formation reactions are defined, any chemical reaction can be written as a combination of formation reactions, some going forward and some going back.

To obtain the enthalpy of the desired chemical reaction you need 2 moles of Al(s) on reactant side and it is present in first equation so let's write this as such.

Now, 1 mole of Fe₂O₃(s)   must be a reactant and is present in the second equation. Since this equation has 1 mole of Fe₂O₃(s)   on the product side, it is necessary to locate the Fe₂O₃(s)  on the reactant side (invert it). When an equation is inverted, the sign of ΔH also changes.

You know that two equations with their corresponding enthalpies are:

Equation 1:  2 Al(s) + [tex]\frac{3}{2}[/tex] O₂(g) → Al₂O₃(s)      ΔH = −1601 kJ/mol  

Equation 2:  Fe₂O₃(s)  → 2 Fe(s) + [tex]\frac{3}{2}[/tex] O₂(g)   ΔH = 821 kJ/mol

Adding or canceling the reactants and products as appropriate, and adding the enthalpies algebraically, you obtain:

2 Al(s) + Fe₂O₃(s) → 2 Fe(s) + Al₂O₃(s)     ΔH= -780 kJ

Finally, the enthalpy change for the reaction is -780 kJ.

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Answer:

1.59 molal

Explanation:

The definition of molality is:

So first we calculate the moles of solute (D-glucose, C₆H₁₂O₆), using its molar mass:

Then we convert grams of water into kg:

Finally we calculate the molality:

The mass of CH₄ required to create 24.0 g of H₂O is 10.67 g

CH₄ + 2O₂ -> CO₂ + 2H₂O

The following were obtained from the balanced equation:

From the balanced equation above,

36 g of H₂O were produced from 16 g of CH₄

From the balanced equation above,

36 g of H₂O were produced from 16 g of CH₄

Therefore,

24 g of H₂O will be produced from = (24 × 16) / 36 = 10.67 g of CH₄

Thus, 10.67 g of CH₄ is needed for the reaction

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Complete question:

See attached photo

Answer: 5000

Explanation:

Answer:

because the cells make drugs at the start of injury!

Answer:

protons and electrons

Explanation:

because two atoms of the same elements have different(mass)isotope so the answer is B

Answer:

30 g/mol

Explanation:

Step 1: Given data

Step 2: Calculate the moles corresponding to 11.2 L of gas

At normal temperature and pressure (1 atm, 293.15 K), 1 mol of a gas has a volume of 24.05 L.

11.2 L × 1 mol/24.05 L = 0.466 mol

Step 3: Calculate the molecular mass of the gas

0.466 moles of the gas weigh 14 g. The molecular mass is:

M = 14 g/0.466 mol = 30 g/mol

Answer:

See explanation

Explanation:

Electronegativity is the ability of an atom in a molecule to attract the  shared electrons of a covalent bond towards itself. Electronegativity is a trend that increases across the period and decreases down the group in the periodic table.

All the compounds listed are halides of phosphorus. The electronegativity of halogens decrease in the order; F> Cl> Br > I. Hence F has the greatest electronegativity in the group. It decreases as atomic and ionic radius increases.

As the electronegativity of the halogen atom decreases, the electron pair on the halogen atom lie closer to the central  phosphorus atom hence the repulsion between electrons increases and so does the bond angle increase likewise.

suppose we have a reaction as follows :

nA + mB ---> pC + qD

where n,m,p,q are natural numbers

these natural numbers are called stoichiometric coefficients .

Eg:

2P + 3Br2 ---> 2PBr3

here, 2, 3 from reactant side and 2 from product side are called stoichiometric coefficients

hope this helps...

Answer:

Wrong

Explanation:

Because they are non metals and tends to form negative charged ions

Answer: The pH 0f 0.10 solution of HCl is 1.00

Explanation:

pH or pOH is the measure of acidity or alkalinity of a solution.

pH is calculated by taking negative logarithm of hydrogen ion concentration.

[tex]pH=-\log [H^+][/tex]

[tex]HCl\rightarrow H^++Cl^{-}[/tex]

According to stoichiometry,  

1 mole of [tex]HCl[/tex] gives 1 mole of [tex]H^+[/tex]  

Thus [tex]0.10[/tex] moles of [tex]HCl[/tex] gives =[tex]\frac{1}{1}\times 0.10=0.10[/tex] moles of [tex]H^+[/tex]  

Putting in the values:

[tex]pH=-\log[0.10][/tex]

[tex]pH=1.00[/tex]

Thus pH 0f 0.10 solution of HCl is 1.00

Answer:

C7H8N4O. The molecular formula C7H8N4O2 (molar mass: 180.16 g/mol) may refer to: Paraxanthine. Theobromine.

Answer:

Volcanic Eruption releases heated ash and Tephra through its column generating its own lightning.

Hope it helps!<3

Answer:

pH = 7.49

Explanation:

This is a buffer solution. We can apply Henderson Hasselbach equation:

pH = pKa + log ((total mmoles - mmoles HCl) / mmoles HCl)

We have the same amount of mmoles.

35 mL . 0.400 M = 14 mmoles HCl

35 mL . 0.400 M = 14 mmoles NaClO

Total moles are 28 mmoles.

We replace data:

pH = pKa + log ((28 mmoles -14 mmoles) / 14 mmoles)

Notice that the relation in log = 1. So pH = pKa

pKa for HClO is 7.49

When pH = pKa we have the same amount of base and acid. Notice, that we have the same mmoles of HCl and NaClO.

Remember that a buffer can be prepared with:

a) A weak acid and its conjugate base (acetic /acetate)

A weak base and its conjugate acid (ammonia/ammonium)

b) A weak acid with a strong base, where the acid can be in excess.

c) A conjugate base (salt from weak acid) with a strong acid, where the base can be in excess. (This case but, the base is not in excess, that's why ph = pKa)

Answer:

180 g Ca

General Formulas and Concepts:

Chemistry - Atomic Structure

Explanation:

Step 1: Define

4.4 mol Ca

Step 2: Identify Conversions

Molar Mass of Ca - 40.08 g/mol

Step 3: Convert

[tex]4.4 \ mol \ Ca(\frac{40.08 \ g \ Ca}{1 \ mol \ Ca} )[/tex] = 176.352 g Ca

Step 4: Check

We are given 2 sig figs. Follow sig fig rules and round.

176.352 g Ca ≈ 180 g Ca

Answer:

0.1739

Explanation:

0.800 mol of N2

0.200 mol of H2

0.150 mol of CH4

Total moles of the mixture = 0.8 + 0.2 + 0.150 = 1.150 mol

Mole fraction of H2 = Number of moles of H2 /  Total moles

Mole Fraction = 0.2 / 1.150 = 0.1739

Answer: The correct answer is Organism.

Explanation:

because.....

that is the part that control the rest.

*Hopefully this helps!!!

Answer:

organism or organ system

Explanation:

i forgot what that dude said up there

Answer:

[tex]Zn(s)+2H^+(aq)\rightarrow Zn^{2+}(aq)+H_2(g)[/tex]

Explanation:

Hello!

In this case, since writing the net ionic equation implies the complete molecular equation, we should start by:

[tex]Zn(s)+2HBr(aq)\rightarrow ZnBr_2(aq)+H_2(g)[/tex]

Next, we represent the ionization of the aqueous species:

[tex]Zn(s)+2H^+(aq)+2Br^-(aq)\rightarrow Zn^{2+}(aq)+2Br^-(aq)+H_2(g)[/tex]

Whereas the spectator ions, those at both reactants and products are cancelled out so the net ionic equation is obtained:

[tex]Zn(s)+2H^+(aq)\rightarrow Zn^{2+}(aq)+H_2(g)[/tex]

Best regards!

Answer:

It is A. hydrogen -2 has one more proton

Explanation:

A formula mass of substance is a sum of the average atomics masses of each atom represented in the chemical formula and is expressed in atomic mass units.the formula mass of covalent compound is also called the molecular mass

Relationship between KMT and Sea Level Rise because sea level rise in KMT with distance of 760nm

KMT is described as the behavior of gases and also it is used to explain macroscopic properties of a gas such a pressure and temperature and sea level rise is an increase in the level of the world oceans due to the effects of global warming and burning fossil fuels is one of the causes of global warming because it releases carbon dioxide and other heat-trapped gasses into the atmosphere so here the relationship between kinetic molecular theory and sea level rise is distance between sea level and KMT is 760nm sea level is rise because gas level is is increases.

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Answer:

maximum amount of solute that is capable of being dissolved

Answer: A solution that contains a maximum amount if solute that is capable of being dissolved

Explanation:

A saturated solution is a solution that contains the maximum amount of solute that is capable of being dissolved.

Answer:A

Explanation:Binary Fission, meaning ‘getting divided into half’ is a type of asexual reproduction where a single living cell grows twice its size and then splits to form two identical daughter cells, each carrying a copy of the parent cell’s genetic material. Examples of cells that use binary fission for division

Answer:

i think its a

Explanation:

Answer:

Ram Ranch

Explanation:

Answer: FLEXUP by lil yacthy and future and playboi carti one of the best songs right now

Explanation:

The answer will be 13.02 % of hydrogen.

Mass Percentage : It is used to estimate the mass % of an element in a compound.

CH3OCH3 - chemical name is dimethyl ether also known by the name of methoxymethane.

It is an organic compound.

Also is an isomer of an ethanol.

There are 6 molecules of Hydrogen present in CH3OCH3

So, mass percent of hydrogen = Total number of molecules present in the compound *100 / Molecular weight of the compound

= 6 *100 / Molar mass of CH3OCH3

= 600 / 46.07 = 13.02 %

So, the mass percentage of hydrogen in C2H6O will be 13.02 %

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Answer:

It is tested by multiple scientist

Explanation:

just took the test, B is correct

Answer:

humans have a huge impact on all spheres. if you negatively impact the spheres, such as burning fossil fuels, it'll pollute the atmosphere.

Explanation:

All four spheres of Earth are susceptible to human influence. Burning fossil fuels can cause pollution to be released into the atmosphere. Garbage accumulated by humans in landfills has an impact on the geosphere. Human waste enters waterways and has an effect on the hydrosphere.

Different definitions of the geosphere have conflicting uses. It can be used to refer to the atmosphere, lithosphere, hydrosphere, and cryosphere as a whole. Different mass and/or energy flows can be exchanged between the various geosphere collectives.

Land erosion and soil movement currently result from human activity more frequently than from any natural mechanism. Human-caused air and water pollution has a negative impact on the environment, rivers, and lakes, harming both other animals and people's health.

According to some scientists, humans have their own sphere, the "anthrosphere." But for the purposes of this module, people will also be considered a component of the biosphere.

Thus, Garbage accumulated by humans in landfills has an impact on the geosphere.

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