A mixture of methane (CH4) and ethane (C2 H6) of mass 13.43 g is completely burned in oxygen. I

A mixture of methane (CH4) and ethane (C2 H6) of mass 13.43...

Key Concepts

Balancing Chemical Equations

Understanding how to balance chemical equations is essential for ensuring the conservation of mass in a chemical reaction. Balanced equations provide the correct stoichiometric coefficients that relate the number of moles of each reactant to the products formed, which is critical for accurate quantitative analysis.

Stoichiometry

Stoichiometry is the quantitative relationship between reactants and products in a chemical reaction, based on the balanced chemical equation. It enables one to calculate the required or produced amounts of substances using mole ratios, which is fundamental in determining compositions in mixtures.

Mole Concept and Molar Mass

The mole concept allows chemists to count particles by relating macroscopic measurements to the number of atoms or molecules present. Molar mass is used to convert between the mass of a substance and the number of moles, a necessary step when applying stoichiometric principles to chemical reactions.

Combustion Reactions

Combustion reactions involve a substance reacting with oxygen to produce combustion products such as carbon dioxide and water, especially in the case of organic compounds. Recognizing these reactions and writing their balanced equations are key steps in analyzing the mass and composition of reactant mixtures.

Conservation of Mass

The conservation of mass principle states that the mass of the reactants must equal the mass of the products in a chemical reaction. This concept is used to set up equations relating the masses of different substances involved in a reaction and is vital for solving problems involving mass comparisons.

Transcript

00:01 Looking at a chemical reaction and at the end we need to find out with what was given to us how to find the fraction of one of the reactants that is existing in this chemical reaction.

00:13 So we're told that a mixture of ethane which you can write out is c -h -4.

00:19 So it's a mixture of methane and another carbon -based molecule, ethane, c2h6.

00:29 So there's a mixture of these two, presumably in gas form.

00:34 And we are told that it is completely burned in oxygen.

00:42 And we are forming, we're told that if the total mass of co2 and h2o produced is x, then how much methane is in the mixture.

00:57 So let's look.

00:59 So we're producing co2, which is obviously a gas.

01:06 And, well, it can be potentially a solid, but that would be dry ice, i believe.

01:15 So it's presumably a gas because at room temperature doesn't like to exist.

01:19 And then we have h2o.

01:21 It doesn't like to exist as a solid that is.

01:23 And then we have h2o.

01:24 So we're also told that, again, it was consumed or completely burned in a gas, the ethane and methane mixture.

01:30 So we need to add our oxygen gas.

01:35 Okay.

01:36 So, and we're told that the amount that is produced is going to be 65.

01:43 So i'll write that in red, 64 .84.

01:47 And there are a few different things we need to do before we can work our way backwards.

01:52 But the first thing is you always want to make sure your reaction is balanced.

01:56 So really quickly, let's count the amount of each elements that's in this reaction.

02:01 We see we have three carbons here.

02:03 So it's three carbons.

02:06 We have 10 hydrogens.

02:11 And we have two oxygen over here.

02:14 If you look on the right side of things, we have one carbons.

02:18 We have three oxygen, and then we have two hydrogen.

02:30 The reaction is not balanced.

02:32 This can be a tricky thing to do.

02:34 Some reactions are easier to balance than others, but if i've already gone ahead and played around with different coefficients, and at the end of the day, if it's balanced, i'll write to the new coefficients in blue.

02:45 This will be the balanced reaction.

02:50 We can count together in one second just to verify.

02:54 So on the left now we have five carbon, right? one here, four here.

03:01 So this is now five.

03:04 Hydrogen, we have four here and 12 here.

03:08 So it's going to be 16 hydrogen.

03:12 And then oxygen, we have just over here nine times two, which is going to be now 18 oxygen.

03:19 On the left, we have five carbon here.

03:25 So that is very well in dandy.

03:28 Have 16 hydrogen here, 8 times 2, 16, and then oxygen, we have 10 here, and then 8 here, which adds up to be 18.

03:42 So, yep, we are balanced.

03:43 So now, just to verify.