Question

Calculate the heat produced by combustion per liter of methanol. Methanol has a density of 0.791 g/mL.

Answer 1

The  heat  produced  by  combustion   per  liter  of  methanol  is  calculated  as follows
heat   released  =  moles  x heat  of  combustion  of  methanol  
heat   of  combustion  of  CH3OH = 715 kj/mol
calculate  moles   first

 that  is ,moles =mass/molar  mass

calculate  the  mass  =  density  x volume(1L=1000ml)
= 0.791  x1000=791  g
molar  mass  of CH3Oh  =  32g/mol

moles  is therefore=   791 g /  32g/mol  =  24.72moles

heat released is therefore=  24.72mole  x  715  Kj/mol =17673.91 KJ

Answer 2

$\boxed{17674.8\;{\text{kJ}}}$ is the heat produced by the combustion per liter of methanol.

Further explanation:

Combustion reactions:

These are the reactions that take place when hydrocarbons are burnt in the presence of oxygen to form carbon dioxide and water. These are also referred to as burning.

Example of combustion reactions are as follows:

(a) ${\text{C}}{{\text{H}}_4}+{{\text{O}}_2}\to{\text{C}}{{\text{O}}_2}+{{\text{H}}_2}{\text{O}}$

(b) ${{\text{C}}_{10}}{{\text{H}}_{14}}+12{{\text{O}}_2}\to10{\text{C}}{{\text{O}}_2}+4{{\text{H}}_2}{\text{O}}$

Heat of combustion:

It is the amount of heat that is released when any substance is burned in the presence of oxygen molecule to form carbon dioxide and water. Its value is a characteristic of the substance.

The balanced chemical reaction for the combustion of methanol is as follows:

$2{\text{C}}{{\text{H}}_{\text{3}}}{\text{OH}}+3{{\text{O}}_2}\to2{\text{C}}{{\text{O}}_2}+4{{\text{H}}_{\text{2}}}{\text{O}}$

The formula to calculate the density of methanol is,

$\text{Density of methanol}=\dfrac{\text{Mass of methanol}}{\text{Volume of methanol}}$                     …… (1)

Rearrange equation (1) to calculate the mass of methanol.${\text{Mass of methanol}}=\left({{\text{Density of methanol}}}\right)\left({{\text{Volume of methanol}}}\right)$          …… (2)

The density of methanol is 0.791 g/mL.

The volume of methanol is 1 L.

Substitute these values in equation (2).

$\align{{\text{Mass of methanol}}&=\left({\frac{{{\text{0}}{\text{.791 g}}}}{{1\;{\text{mL}}}}}\right)\left({\frac{{{{10}^3}\;{\text{mL}}}}{{1{\text{L}}}}}\right)\left({{\text{1 L}}}\right)\cr&=791\;{\text{g}}\cr}$

The formula to calculate the moles of methanol is as follows;

$\text{Moles of methanol}=\dfrac{\text{Given mass of methanol}}{\text{Molar mass of methanol}}$

(3)

The given mass of methanol is 791 g.

The molar mass of methanol is 32 g/mol.

Substitute these values in equation (3).

$\align{{\text{Moles of methanol}}&=\left( {{\text{791 g}}}\right)\left({\frac{{{\text{1 mol}}}}{{{\text{32 g}}}}}\right)\cr&=24.718\;{\text{mol}}\cr\approx&{\bf{24}}{\bf{.72}}\;{\bf{mol}}\cr}$

The expression to calculate the heat produced by combustion of methanol is,

${\text{Heat produced}}=\left({{\text{Moles of methanol}}}\right)\left({{\text{Heat of combustion of methanol}}}\right)$

(4)

The moles of methanol is 24.72 mol.

The heat of combustion of methanol is 715 kJ/mol.

Substitute these values in equation (4).

$\align{{\text{Heat produced}}&=\left({{\text{24}}{\text{.72 mol}}}\right)\left({\frac{{{\text{715 kJ}}}}{{{\text{1 mol}}}}}\right)\cr&=17674.8\,\;{\text{kJ}}\cr}$

So the heat produced by the combustion of methanol per liter is $17674.8\,\;{\text{kJ}}$

Learn more:

1. Calculate $\Delta{\text{H}}$ for the reaction using Hess law: brainly.com/question/11293201

2. Calculate the hydroxide ion concentration: brainly.com/question/11293214

Answer details:

Grade: Senior School

Subject: Chemistry

Chapter: Thermodynamics

Keywords: combustion, density, methanol, heat of combustion, molar mass, volume of methanol, mass of methanol, 17674.8 kJ, 24.72 mol, 715 kJ, 0.791 g/mL.