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3 years ago

The enthalpies of formation of the compounds in the combustion of methane,

Chemistry

2 answers:

Naya [18.7K]3 years ago

5 0

Answer:

The amount of heat released by the combustion of 2 moles of methane = 1605.1 kJ

Option 3 is correct.

ΔH°(combustion of 2 moles of methane)

= -1,605.1 kJ

Explanation:

The balanced equation for the combustion of methane is presented as

CH₄ + 2O₂ → CO₂ + 2H₂O

The heat of formation for the reactants and products are

CH₄ (g): ΔHf = –74.6 kJ/mol;

CO₂ (g): ΔHf = –393.5 kJ/mol;

and H₂O(g): ΔHf = –241.82 kJ/mol.

ΔHf for O₂ = 0 kJ/mol

ΔH°rxn for the combustion of methane is given as

ΔH°rxn = ΣnH°(products) - ΣnH°(reactants)

ΣnH°(products) = (1×-393.5) + (2×-241.82)

= -877.14 kJ/mol

ΣnH°(reactants) = (1×-74.6) + (2×0)

= -74.6 kJ/mol

ΔH°rxn = -877.14 - (-74.6) = -802.54 kJ/mol

For 2 moles of methane, the heat of combustion = 2 moles × -802.54 kJ/mol

= -1,605.08 kJ = -1,605.1 kJ

Hope this Helps!!!

inn [45]3 years ago

4 0

Answer:

C, -1,605.1 kJ

Explanation:

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3 years ago

A buffer solution contains 0.496 M hydrocyanic acid and 0.399 M sodium cyanide . If 0.0461 moles of sodium hydroxide are added t

pochemuha

Answer : The pH of the solution is, 9.63

Explanation : Given,

The dissociation constant for HCN = $pK_a=9.31$

First we have to calculate the moles of HCN and NaCN.

$\text{Moles of HCN}=\text{Concentration of HCN}\times \text{Volume of solution}=0.496M\times 0.225L=0.1116mole$

and,

$\text{Moles of NaCN}=\text{Concentration of NaCN}\times \text{Volume of solution}=0.399M\times 0.225L=0.08978mole$

The balanced chemical reaction is:

$HCN+NaOH\rightarrow NaCN+H_2O$

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0.0655 0.1359

Now we have to calculate the pH of the solution.

Using Henderson Hesselbach equation :

$pH=pK_a+\log \frac{[Salt]}{[Acid]}$

Now put all the given values in this expression, we get:

$pH=9.31+\log (\frac{0.1359}{0.0655})$

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3 years ago

Explain the meaning of each term in the symbol aXz

Ede4ka [16]

AXz

Explanation:

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A is the mass number of element

A=n+p(sum of protons and neutrons)

Z is the atomic number.

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Hers X is C, symbol of carbon

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Answer:

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3 years ago

Read 2 more answers

Complete and balance the following redox equation using the set of smallest whole– number coefficients. Now sum the coefficients

Elena L [17]

Answer : The balanced chemical equation in a acidic solution is,

$BrO_3^-(aq)+6H^+(aq)+3Sb^{3+}(aq)\rightarrow Br^-(aq)+3H_2O(l)+3Sb^{5+}(aq)$

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Explanation :

Redox reaction or Oxidation-reduction reaction : It is defined as the reaction in which the oxidation and reduction reaction takes place simultaneously.

Oxidation reaction : It is defined as the reaction in which a substance looses its electrons. In this, oxidation state of an element increases. Or we can say that in oxidation, the loss of electrons takes place.

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Rules for the balanced chemical equation in acidic solution are :

First we have to write into the two half-reactions.

Now balance the main atoms in the reaction.

Now balance the hydrogen and oxygen atoms on both the sides of the reaction.

If the oxygen atoms are not balanced on both the sides then adding water molecules at that side where the less number of oxygen are present.

If the hydrogen atoms are not balanced on both the sides then adding hydrogen ion $(H^+)$ at that side where the less number of hydrogen are present.