Liquid methanol (CH4 O), which is used as a cooking fuel, burns with oxygen gas to produce the g

Liquid methanol (CH4 O), which is used as a cooking fuel,...

Liquid methanol $\left(\mathrm{CH}_{4} \mathrm{O}\right),$ which is used as a cooking fuel, burns with oxygen gas to produce the gases carbon dioxide and water. The reaction produces $363 \mathrm{~kJ}$ of heat per mole of methanol. (7.4,7.7,7.8,7.9) a. Write a balanced equation for the reaction, including the heat of reaction. b. Is the reaction endothermic or exothermic? c. How many moles of $\mathrm{O}_{2}$ must react with $0.450 \mathrm{~mole}$ of $\mathrm{CH}_{4} \mathrm{O} ?$ d. How many grams of $\mathrm{CO}_{2}$ are produced when $78.0 \mathrm{~g}$ of $\mathrm{CH}_{4} \mathrm{O}$ reacts?

Liquid methanol $\left(\mathrm{CH}_{4} \mathrm{O}\right),$ which is used as a cooking fuel, burns with oxygen gas to produce the gases carbon dioxide and water. The reaction produces $363 \mathrm{~kJ}$ of heat per mole of methanol. (7.4,7.7,7.8,7.9)
a. Write a balanced equation for the reaction, including the heat of reaction.
b. Is the reaction endothermic or exothermic?
c. How many moles of $\mathrm{O}_{2}$ must react with $0.450 \mathrm{~mole}$ of $\mathrm{CH}_{4} \mathrm{O} ?$
d. How many grams of $\mathrm{CO}_{2}$ are produced when $78.0 \mathrm{~g}$ of $\mathrm{CH}_{4} \mathrm{O}$ reacts?

Key Concepts

Balancing Chemical Equations

This concept involves writing chemical equations such that the number of atoms for each element is equal on both the reactant and product sides. It ensures that the law of conservation of mass is maintained during the reaction. In practice, balancing equations often includes adding appropriate coefficients to reactants and products and may also incorporate additional information like energy changes.

Thermochemistry (Exothermic and Endothermic Reactions)

Thermochemistry is the study of the heat energy changes that accompany chemical reactions. An exothermic reaction releases heat to the surroundings, whereas an endothermic reaction absorbs heat. Including the heat of reaction in the chemical equation using a delta (?) notation helps indicate whether the reaction gives off or takes in heat energy.

Stoichiometry

Stoichiometry involves using the quantitative relationships between reactants and products as indicated by a balanced chemical equation. This concept allows one to calculate how many moles of one substance are needed or produced when a given amount of another substance reacts, based on their mole ratios.

Mass-Mole Conversions

Mass-mole conversions are fundamental to chemical calculations and involve using the molar mass of a substance to convert between the mass (in grams) and the amount (in moles). This conversion is crucial for applying stoichiometric relationships when given masses of reactants or products.

Transcript

00:01 All right, so we're told that liquid methanol reacts with oxygen, and we're given the amount of heat that is liberated.

00:08 We're first told to write the equation of that reaction, and to include the heat of the reaction.

00:17 So basically we have ch3oh, which is emitted as plus oxygen gas, and would have co2 and water.

00:32 If you balance, you see that this should be two, right? so this is going to be four, this is also going to be two, and this will be three.

00:43 So this is balanced.

00:44 Now the delta h of this reaction is, it is liberated, it's a combustion reaction, which tells you that the reaction produces 363 kilojoules per mole.

01:00 But you see that this equation, right? there are two moles of methanol.

01:05 So the heat of this reaction is twice of that.

01:09 That's it.

01:10 The heat of this reaction is twice of that, three times two of that.

01:16 So actually, the heat of this reaction is going to be 726 kilojoules.

01:23 Now if we're to write this equation to include that, so because it's a combustion reaction, and it's exothermic, i've answered one of the questions already.

01:30 So this is 2oh plus three moles of o2 to give us two moles of co2 plus four moles of water, and then we add 726 kilojoules.

01:44 This would be the equation of the reaction, right? and you can see that the heat produced is on the product side.

01:52 And i said, because the equation has two moles of methanol, that's why we have that to be the heat of the reaction.

02:03 And the second part says, is it endo or exo? it is exothermic.

02:06 Combustion reactions are exothermic reactions...

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