Diethyl ether, \(\mathrm{C}_{4} \mathrm{H}_{10} \mathrm{O}(l),\) a flammable compound that has long been used as a surgical anesthetic, has the structure \(\mathrm{CH}_{3}-\mathrm{CH}_{2}-\mathrm{O}-\mathrm{CH}_{2}-\mathrm{CH}_{3}\) The complete combustion of \(1 \mathrm{~mol}\) of \(\mathrm{C}_{4} \mathrm{H}_{10} \mathrm{O}(l)\) to \(\mathrm{CO}_{2}(g)\) and \(\mathrm{H}_{2} \mathrm{O}(l)\) yields \(\Delta H^{\circ}=-2723.7 \mathrm{~kJ}\). (a) Write a balanced equation for the combustion of \(1 \mathrm{~mol}\) of \(\mathrm{C}_{4} \mathrm{H}_{10} \mathrm{O}(l)\) (b) Write a balanced equation for the formation of \(\mathrm{C}_{4} \mathrm{H}_{10} \mathrm{O}(l)\) from its elements. (c) By using the information in this problem and data in Table \(5.3,\) calculate \(\Delta H_{f}^{\circ}\) for diethyl ether.

Short Answer

Expert verified
The balanced equations are: 1. Combustion: \( C_{4}H_{10}O(l) + 6\frac{1}{2} O_{2}(g) \rightarrow 4 CO_{2}(g) + 5 H_{2}O(l) \) 2. Formation: \( 4 C + 5 H_{2} + \frac{1}{2} O_{2} \rightarrow C_{4}H_{10}O \) The standard enthalpy of formation for diethyl ether is \( \Delta H_{f}^{\circ}(C_{4}H_{10}O) = -261.6 \mathrm{~kJ/mol} \).

Step by step solution

01

Write the Balanced Combustion Equation

To write the balanced equation for the combustion of 1 mol of diethyl ether (C4H10O), we need to know that: - Complete combustion means the reactants are Diethyl ether and O2; the products are CO2 and H2O. - The coefficients should be adjusted so that the atoms are conserved. The unbalanced equation looks like this: C4H10O(l) + O2(g) → CO2(g) + H2O(l) Now, balance the equation by adjusting the coefficients: C4H10O(l) + \(6\frac{1}{2}\) O2(g) → 4 CO2(g) + 5 H2O(l)
02

Write the Balanced Formation Equation

To write the balanced equation for the formation of diethyl ether from its elements, we need to know that: - Formation means the reactants are the elements in their standard states; the product is diethyl ether. - The coefficients should be adjusted so that the atoms are conserved. The unbalanced equation looks like this: C + H2 + O2 → C4H10O Now, balance the equation by adjusting the coefficients: 4 C + 5 H2 + \( \frac{1}{2} \) O2 → C4H10O
03

Calculate the Standard Enthalpy of Formation

To calculate the standard enthalpy of formation for diethyl ether, use the given information and the standard enthalpy of formation for the involved species from Table 5.3. We use the following equation: ∆Hf°(C4H10O) = ∆H°(products) - ∆H°(reactants) First, gather the standard enthalpy of formation values from table 5.3: ∆Hf°(C) = 0 kJ/mol (as carbon is in its standard state) ∆Hf°(H2) = 0 kJ/mol (as hydrogen is in its standard state) ∆Hf°(O2) = 0 kJ/mol (as oxygen is in its standard state) ∆Hf°(CO2) = -393.5 kJ/mol ∆Hf°(H2O) = -285.8 kJ/mol Now, we calculate the enthalpy change for the combustion of C4H10O from the given information: ∆H°(combustion) = -2723.7 kJ According to the balanced combustion equation (Step 1): ∆H°(combustion) = 4 ∆Hf°(CO2) + 5 ∆Hf°(H2O) - ∆Hf°(C4H10O) -2723.7 kJ = 4(-393.5 kJ/mol) + 5(-285.8 kJ/mol) - ∆Hf°(C4H10O) Now, solve for ∆Hf°(C4H10O): ∆Hf°(C4H10O) = 4(-393.5 kJ/mol) + 5(-285.8 kJ/mol) + 2723.7 kJ ∆Hf°(C4H10O) = - 261.6 kJ/mol The standard enthalpy of formation for diethyl ether is -261.6 kJ/mol.

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Most popular questions from this chapter

From the enthalpies of reaction $$ \begin{aligned} 2 \mathrm{C}(s)+\mathrm{O}_{2}(g) & \longrightarrow 2 \mathrm{CO}(g) & \Delta H=&-221.0 \mathrm{~kJ} \\ 2 \mathrm{C}(s)+\mathrm{O}_{2}(g)+4 \mathrm{H}_{2}(g) & \longrightarrow 2 \mathrm{CH}_{3} \mathrm{OH}(g) & \Delta H=&-402.4 \mathrm{~kJ} \end{aligned} $$ calculate \(\Delta H\) for the reaction $$ \mathrm{CO}(g)+2 \mathrm{H}_{2}(g) \longrightarrow \mathrm{CH}_{3} \mathrm{OH}(g) $$

(a) Why is the change in enthalpy usually easier to measure than the change in internal energy? (b) \(H\) is a state function, but \(q\) is not a state function. Explain. (c) For a given process at constant pressure, \(\Delta H\) is positive. Is the process endothermic or exothermic?

The heat of combustion of ethanol, \(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}(l),\) is \(-1367 \mathrm{~kJ} / \mathrm{mol}\). A batch of Sauvignon Blanc wine contains \(10.6 \%\) ethanol by mass. Assuming the density of the wine to be \(1.0 \mathrm{~g} / \mathrm{mL},\) what is the caloric content due to the alcohol (ethanol) in a 6 -oz glass of wine \((177 \mathrm{~mL}) ?\)

(a) Write an equation that expresses the first law of thermodynamics in terms of heat and work. (b) Under what conditions will the quantities \(q\) and \(w\) be negative numbers?

It is estimated that the net amount of carbon dioxide fixed by photosynthesis on the landmass of Earth is \(5.5 \times 10^{16} \mathrm{~g} /\) yr of \(\mathrm{CO}_{2}\). Assume that all this carbon is converted into glucose. (a) Calculate the energy stored by photosynthesis on land per year in kJ. (b) Calculate the average rate of conversion of solar energy into plant energy in \(\mathrm{MW}(1 \mathrm{~W}=1 \mathrm{~J} / \mathrm{s}) .\) A large nuclear power plant produces about \(10^{3} \mathrm{MW}\). The energy of how many such nuclear power plants is equivalent to the solar energy conversion?

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