Chemistry, 13.11.2019 22:31 shartman22

Ethanol, c2h6o, is most often blended with gasoline - usually as a 10 per cent mix - to create a fuel called gasohol. ethanol is a renewable resource and ethanol-blended fuels, like gasohol, appear to burn more efficiently in combustion engines. the heat of combustion of ethanol is 326.7 kcal/mol.
the heat of combustion of 2-methylheptane, c8h18, is 1.306×103 kcal/mol. how much energy is released during the complete combustion of 394 grams of 2-methylheptane ?

assuming the same efficiency, would 394 grams of ethanol provide more, less, or the same amount of energy as 394 grams of 2-methylheptane?

a. more or
b. less or
c. the same amount

Answers: 2

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Answer from: victoriay3

4.51 × 10³ kcal

B. less

Explanation:

Let's consider the combustion of 2-methylheptane.

C₈H₁₈ + 12.5 O₂ ⇒ 8 CO₂ + 9 H₂O

When 1 mole of C₈H₁₈ burns, 1.306 × 10³ Kcal are released (heat of combustion). The molar mass of C₈H₁₈ is 114 g/mol. Then, for 394 g of C₈H₁₈:

$394gC_{8}H_{18}.\frac{1molC_{8}H_{18}}{114gC_{8}H_{18}}.\frac{1.306 \times 10^{3} kcal }{1molC_{8}H_{18}} =4.51 \times 10^{3} kcal$

Assuming the same efficiency, would 394 grams of ethanol provide more, less, or the same amount of energy as 394 grams of 2-methylheptane?

Let's consider the combustion of ethanol.

C₂H₆O + 3 O₂ ⇒ 2 CO₂ + 3 H₂O

When 1 mole of C₂H₆O burns, 326.7 Kcal are released (heat of combustion). The molar mass of C₂H₆O is 46.0 g/mol. Then, for 394 g of C₂H₆O:

$394gC_{2}H_{6}O.\frac{1molC_{2}H_{6}O}{46.0gC_{2}H_{6}O}.\frac{326.7 kcal }{1molC_{2}H_{6}O} =2.80 \times 10^{3} kcal$

The combustion of 394 g of ethanol provides less energy than the combustion of 394 g of 2-methylheptane.

Answer from: Quest

answer: any goods being imported from another country may be subject to issued by the federal government are tariffs

explanation:

tariffs are a tax on anything that are imported from abroad. government use them to protect and boost their local industries and the thought is that they encourage consumers to buy local instead of importing and they will hope will protect jobs and economy in the country that implements them

Answer from: Quest

Answerthe half-reaction having the greatest tendency to occur at the anode: i₂(aq) + 2e⁻ ⇄ 2i⁻ ; e = +0.53 v====== $\begin{aligned} \text{i}_2\text{\footnotesize (aq)}+2\,\text{e}^{-} & \rightleftharpoons 2\,\text{i}^{-}\text{\footnotesize (aq)}& \text{e} & = +0.53\text{ v} \\ \text{co}^{3+}\text{\footnotesize (aq)} + \text{e}^{-} & \rightleftharpoons \text{co}^{2+}\text{\footnotesize (aq)} & \text{e} & = +1.80\text{ v} \\ \text{o}_2\text{\footnotesize (g)}+4\,\text{h}^{+}\text{\footnotesize (aq)} + 4\,\text{e}^{-} & \rightleftharpoons 2\,\text{h}_2\text{o}\text{\footnotesize(l)}& \text{e} & = +1.23\text{ v} \\ \end{aligned}$ oxidation occurs at the anode. we must therefore find the half-reaction with the greatest tendency to oxidize.the given values of e are reduction potentials (the form of the half-reactions are of reduction).the lower the reduction potential, the higher the potential to oxidize. the half-cell with the lowest reduction potential will have the greatest tendency to oxidize at the anode.the half-reaction having the greatest tendency must be i₂(aq) + 2e⁻ ⇄ 2i⁻ e = +0.53 vbecause its reduction potential is the lowest out of the three.

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Ethanol, c2h6o, is most often blended with gasoline - usually as a 10 per cent mix - to create a fue...

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