Write the balanced chemical equation for the complete...

Write the balanced chemical equation for the complete combustion of heptene, $\mathrm{C}_{7} \mathrm{H}_{14}$. In combustion, heptene reacts with oxygen to produce carbon dioxide and water. What is the mole ratio that would enable you to calculate the number of moles of oxygen needed to react exactly with a given number of moles of heptene? What mole ratios would you use to calculate how many moles of each product form from a given number of moles of heptene?

Key Concepts

Balanced Chemical Equations

A balanced chemical equation represents a chemical reaction in which the number of atoms of each element is equal on both sides of the equation. This is crucial because it reflects the conservation of mass. In combustion reactions, such as that of heptene, the organic compound reacts with oxygen to produce carbon dioxide and water, and the equation must be balanced to accurately reflect the ratio of molecules involved.

Combustion Reactions

Combustion reactions are exothermic chemical processes in which a fuel reacts with an oxidizing agent, typically oxygen, producing heat and light. In the complete combustion of hydrocarbons such as heptene, the products are carbon dioxide and water. Understanding the combustion process requires not only balancing the equation but also determining the precise mole ratios to predict the amounts of oxygen required and products formed.

Mole Ratios

Mole ratios are derived from the coefficients of a balanced chemical equation and indicate the relative numbers of moles of reactants and products that participate in the reaction. For example, from the balanced combustion equation for heptene, the mole ratio of oxygen to heptene tells you how many moles of oxygen are needed to completely combust a mole of heptene, while the mole ratios relating to the products inform you of the amounts of carbon dioxide and water formed per mole of heptene consumed.

Stoichiometry

Stoichiometry is the part of chemistry that involves calculating the relative quantities of reactants and products in a chemical reaction. It uses the coefficients from a balanced chemical equation to determine the mole ratios between substances, which allows for conversion from moles of one compound to moles of another, ensuring that the law of conservation of mass is obeyed in chemical reactions.

Transcript

00:01 So we're going to write the balanced equation for the combustion of heptene.

00:06 In hepteen, it gives us formula of c7h14.

00:13 So in combustion reactions, we're always going to react with oxygen.

00:17 So it'll be one of our reactants.

00:20 And we're going to have this yields.

00:22 And if we're combusting hydrocarbons, so things with hydrogen and carbon end up, we typically get carbon dioxide as a product.

00:32 We get water as a product.

00:38 All right.

00:39 So i'm just going to put lines here where we're going to put our coefficients.

00:42 So sometimes balancing combustion reactions can be a bit tricky.

00:46 So i'm going to start with some blue.

00:48 So if i see i have seven carbons on this side.

00:51 Notice the only place that carbon appears on the right hand side is in carbon dioxide.

00:55 So i'm going to go ahead and put seven right here.

00:58 Similarly, i've got 14 hydrogens on the left or on the reactant side.

01:02 And the only place that hydrogen appears on the right is in water.

01:05 So because of water, has two hydrogens, i'm going to put a seven coefficient here because seven times two is 14.

01:12 So at this point, i've got one heptene, seven carbon dioxide, and seven waters.

01:19 So now if i look at all of my oxygens on the right, i've got seven times two.

01:26 So i have 14 oxygens coming from carbon dioxide.

01:31 And then i have seven times one, or seven oxygens coming from water.

01:40 So really i need 21 oxygens over here.

01:44 But because o2 is a diatomic element, if i need 21, what ends up happening is i really need 10 and a half to go on that line...

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