Calculate the mass percent composition of each of the following substances: (a) Malachite, a cop

Calculate the mass percent composition of each of the...

Key Concepts

Atomic Mass

Atomic mass is the mass of an individual atom of an element, often expressed in atomic mass units (amu). This value is drawn from the weighted average of the masses of an element's naturally occurring isotopes, and it is used in calculating both the molar masses of compounds and the contributions of individual elements to the total mass.

Molar Mass Calculation

Molar mass is the sum of the atomic masses of all the atoms in a molecule, each multiplied by its frequency within the molecule. This calculation is fundamental in converting between the mass of a substance and the amount in moles, and it is essential for determining the mass percent composition of each element in a compound.

Mass Percent Composition

Mass percent composition is the fraction (expressed as a percentage) of each element's mass relative to the total molar mass of a compound. This concept is crucial for understanding how much of each element is present in a sample by mass, and it is determined by dividing the mass of a specific element (derived from its atomic mass multiplied by the number of atoms in the formula) by the compound’s total molar mass.

Chemical Formula

A chemical formula represents the types and numbers of atoms present in a compound. It serves as the blueprint for the compound, allowing one to calculate properties like the molar mass and to analyze the composition and structure of the compound.

Transcript

00:01 In this problem, we are asked to solve the mass percent composition of three different molecules.

00:08 To solve for the mass percent composition, we will need to use the formula shown above.

00:16 In part a, we are given malachite, which is the chemical formula is given here.

00:25 First, we would need to find the mole ratio between each individual element that is composed of this chemical.

00:36 We know that in malachite, there is copper, oxygen, hydrogen, and carbon.

00:45 The ratio between these different elements within this chemical is 2 to 5 to 2 to 1.

00:54 As we can see here, there is no common denominator, so this is the smallest number that we can reduce the ratio to.

01:05 Next, we will calculate how many grams of each individual element there are.

01:12 For one mole of malachite, we will have two moles of copper, as shown above.

01:21 And for the molar mass, we know that one mole of copper, is equivalent to 63 .55 grams of copper, which will give us 121 .7 grams of copper.

01:36 Next, for one mole of malachite, we will have 5 moles of oxygen.

01:43 And for one mole of oxygen, we know the molar mass is 16 grams of oxygen, which will give us 80 grams of oxygen in malachite.

01:53 And next, in 1 mole of malachite, we will have 2 moles of hydrogen.

02:01 And per 1 mole hydrogen, we will have 1 .01 grams of hydrogen for its molar mass.

02:09 So for 1 mole of malachite, we will have 2 .02 grams of hydrogen.

02:15 Lastly, we will solve for the number of grams of carbon inside of malachite.

02:20 For 1 mole of malachite, we will have 1 mole of carbon.

02:26 And for 1 mole of carbon, we know that the molar mass will be 12 grams of carbon, which will give us a total of 12 grams of carbon per 1 mole of malachite.

02:42 Going back to the mass percent composition equation, we need to find the total mass.

02:49 We need to find the total mass in order to solve for the mass percent.

02:54 The total mass of malachite is the sum of all of these individual elements of copper, oxygen, hydrogen, and carbon, which is given over here.

03:08 This will give us 215 .7 grams, which is our total mass of malachite.

03:19 Next, we can solve for our individual mass percent composition of each element inside of malachi, using the equation above.

03:30 We know that the percent of copper is 121 .7 grams of copper over the total mass, which is 215 .7 grams, times 100%, which will give us 56 .4%.

03:49 So 56, that will be the mass percent composition of copper in malachite.

03:56 For the percent composition of oxygen, we will do the same thing.

04:02 We know that we have 80 grams of oxygen over our total mass, which is 215 .7 grams, times 100%, which gives us 37 .1 % composition of oxygen in malachite.

04:17 Moving on to hydrogen, we will do the same thing.

04:21 We have 2 .02 grams of hydrogen over our total mass times 100%, which gives us 0 .94 % of hydrogen.

04:33 Lastly, we will solve for the percent composition of carbon.

04:38 We know that there are 12 grams of carbon and 1 mole of malachite over the total mass times 100%, which will give us 5 .6 % of carbon in one mole percent composition in one mole of malachite.

04:56 If we add these percentages together, we should have approximately 100%.

05:02 Because we are rounding numbers in the process of calculating grams of each element, there might be a slight rounding error.

05:11 So our total percent should be approximately 100%.

05:18 Next, we are given acetaminophen, which is given in this chemical equation.

05:24 We know that there are four elements in total that's composed in this element, carbon, hydrogen, nitrogen, and oxygen, and as we count the number of each element in the chemical equation, we know that there is an 8 to 9 to 1 to 2 ratio.

05:41 Like before, there is no common denominator, so this is the best we can do in reducing this ratio.

05:49 Next, as like before, we will calculate the mass of each element in one mole of acetaminophen...

Please give Ace some feedback