Methanol is the fuel in "canned heat" containers (e.g....

Methanol is the fuel in "canned heat" containers (e.g. Sterno) that are used to heat foods at cocktail parties. The combustion of methanol can be described by the following thermochemical equation: $$ \begin{array}{r} 2 \mathrm{CH}_{3} \mathrm{OH}(l)+3 \mathrm{O}_{2}(g) \longrightarrow 2 \mathrm{CO}_{2}(g)+4 \mathrm{H}_{2} \mathrm{O}(g) \\ \Delta H^{\circ}=-1199 \mathrm{~kJ} \end{array} $$ How many kilojoules are liberated by the combustion of $46.0 \mathrm{~g}$ of methanol?

Methanol is the fuel in "canned heat" containers (e.g. Sterno) that are used to heat foods at cocktail parties. The combustion of methanol can be described by the following thermochemical equation:
$$
\begin{array}{r}
2 \mathrm{CH}_{3} \mathrm{OH}(l)+3 \mathrm{O}_{2}(g) \longrightarrow 2 \mathrm{CO}_{2}(g)+4 \mathrm{H}_{2} \mathrm{O}(g) \\
\Delta H^{\circ}=-1199 \mathrm{~kJ}
\end{array}
$$
How many kilojoules are liberated by the combustion of $46.0 \mathrm{~g}$ of methanol?

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Key Concepts

Thermochemistry (Enthalpy Change)

Thermochemistry involves the study of heat changes in chemical reactions. The enthalpy change (?H) of a reaction quantifies the energy absorbed or released during the reaction under constant pressure. It allows for the calculation of energy changes based on the stoichiometrically determined amounts of reactants or products.

Molar Mass

Molar mass is the mass of one mole of a substance, typically expressed in grams per mole. It is used as a conversion factor to relate the mass of a chemical substance to the amount in moles, which is necessary when applying stoichiometric calculations in chemical reactions.

Balanced Chemical Equation

A balanced chemical equation represents a chemical reaction where the number of atoms for each element is equal on both sides of the formula. This is essential for applying stoichiometry because the coefficients indicate the proportion of reactants and products involved in the reaction.

Stoichiometry

Stoichiometry involves using the relationships provided by a balanced chemical equation to calculate the amounts of reactants or products in a chemical reaction. In thermochemical calculations, it is used to convert from the mass of a substance to the moles and then to the energy released or absorbed as indicated by the reaction’s enthalpy change.

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