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WITCHER [35]
3 years ago
9

The enthalpy of combustion for octane (C8H18(l)), a key component of gasoline, is -5,074 kJ/mol. This value is the Delta. Hrxn f

or which of the following reactions? 2C8H18(l) 25O2(g) Right arrow. 16CO2(g) 18H2O(g) C8H18(l) 12. 5O2(g) Right arrow. 8CO2(g) 9H2O(g) 16CO2(g) 18H2O(g) Right arrow. 2C8H18(l) 25O2(g) 8CO2(g) 9H2O(g) Right arrow. C8H18(l) 12. 5O2(g).
Chemistry
1 answer:
Inessa [10]3 years ago
6 0

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.

<h3>What is the enthalpy of reaction?</h3>

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.

Learn more about enthalpy of reaction, here:

brainly.com/question/1657608

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What is the volume of 14.0g of nitrogen gas at STP?
lozanna [386]

Answer:

  • <em>The volume of 14.0 g of nitrogen gas at STP is </em><u><em>11.2 liter.</em></u>

Explanation:

STP stands for standard pressure and temperature.

The International Institute of of Pure and Applied Chemistry, IUPAC changed the definition of standard temperature and pressure (STP) in 1982:

  •   Before the change, STP was defined as a temperature of 273.15 K and an absolute pressure of exactly 1 atm (101.325 kPa).

  •    After the change, STP is defined as a temperature of 273.15 K and an absolute pressure of exactly 105 Pa (100 kPa, 1 bar).

Using the ideal gas equation of state, PV = nRT you can calculate the volume of one mole (n = 1)  of gas. With the former definition, the volume of a mol of gas at STP, rounded to 3 significant figures, was 22.4 liter. This is classical well known result.

With the later definition, the volume of a mol of gas at STP is 22.7 liter.

I will use the traditional measure of 22.4 liter per mole of gas.

<u>1) Convert 14.0 g of nitrogen gas to number of moles:</u>

  • n = mass in grams / molar mass
  • Atomic mass of nitrogen: 14.0 g/mol
  • Nitrogen gas is a diatomic molecule, so the molar mass of nitrogen gas = molar mass of N₂ = 14.0 × 2 g/mol = 28.0 g/mol
  • n = 14.0 g / 28.0 g/mol = 0.500 mol

<u>2) Set a proportion to calculate the volume of nitrogen gas:</u>

  • 22.4 liter / mol = x  / 0.500 mol
  • Solve for x: x = 0.500 mol × 22.4 liter / mol = 11.2 liter.

<u>Conclusion:</u> the volume of 14.0 g of nitrogen gas at STP is 11.2 liter.

6 0
3 years ago
a 6.7 volume of air, initially at 23 degrees celsius and .98 atm, is compressed to 2.7 L while heated to 125 degrees celsius. Wh
Annette [7]
Data:

V1 = 6.7 liter
T1 = 23° = 23 + 273.15 K = 300.15 K
P1 = 0.98 atm

V2 = 2.7 liter
T2 = 125° = 125 + 273.15 K = 398.15 K
P2 = ?

Formula:

Combined law of ideal gases: P1 V1 / T1 = P2 V2 / T2

=> P2 = P1 V1 T2 / (T1 V2)

P2 = 0.98 atm * 6.7 liter * 398.15 K / (300.15K * 2.7 liter)

P2 = 3.22 atm
6 0
3 years ago
Calcium carbide, CaC2, reacts with water to form calcium hydroxide and the flammable gas ethyne (acetylene) in the reaction: Wha
AysviL [449]

Answer:

1 mole of CaC₂ will produce 26g of C₂H₂ or 64.1g of CaC₂ will produce 26g of C₂H₂

Explanation:

Hello,

To solve this question, we'll require a balanced chemical equation of reaction between calcium carbide and water.

Equation of reaction

CaC₂ + 2H₂O → Ca(OH)₂ + C₂H₂

Molar mass of calcium carbide (CaC₂) = 64.1g/mol

Molar mass of water (H₂O) = 18g/mol

Molar mass of calcium hydroxide (Ca(OH)₂) = 74g/mol

Molar mass of ethyne (C₂H₂) = 26g/mol

From the equation of reaction, 1 mole of CaC₂ will produce 1 mole of C₂H₂

1 mole of CaC₂ = mass / molar mass

Mass = 1 × 64.1

Mass = 64.1g

1 mole of C₂H₂ = mass / molar mass

Mass = 1 × 26

Mass = 26g

Therefore, 1 mole of CaC₂ will produce 26g of C₂H₂

Note: this is a hypothetical calculation since we were not given the initial mass of CaC₂ that starts the reaction

7 0
3 years ago
A droplet of pure mercury has a density of 13.6 g/cm3. What is the density of a sample of pure mercury that is 10 times as large
soldier1979 [14.2K]
<span>density is an intensive property of the matter, it doesnt change with the change of mass for the same substance, at the same pressure and temperature</span>
7 0
3 years ago
This
timama [110]

Answer:

4.2 Liters (2 sig-figs)

Explanation:

Apply Boyles Law ... P₁V₁ = P₂V₂

P₁ = 712 Torr      P₂ = 3560 Torr

V₁ = 21.0L           V₂ = ?

P₁V₁ = P₂V₂ => V₂ = P₁V₁/P₂ = (712Torr)(21.0L)/(3560Torr) = 4.2 Liters (2 sig-figs)

8 0
3 years ago
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