Cysteine, shown here, is one of the 20 amino acids found in proteins in humans. Write the molecu

step 1 We have given information. There are three carbon atoms, one nitrogen atom, one sulfur atom, two

Cysteine, shown here, is one of the 20 amino acids found in...

Key Concepts

Molecular Formula

The molecular formula represents the number and types of atoms present in a molecule. It shows the composition by listing each element symbol followed by a subscript indicating the number of atoms of that element in one molecule. This concept is fundamental in chemistry as it provides the basic information needed to understand a compound’s structure and properties.

Percent Composition by Mass

Percent composition by mass is the calculation of the mass percentage of each element in a compound. To determine this, the mass contribution of each element (obtained by multiplying the number of atoms by the atomic mass) is divided by the compound's total molecular mass, and the result is multiplied by 100. This calculation is crucial for understanding the elemental makeup of a substance and for applications in analytical chemistry.

Amino Acids

Amino acids are the building blocks of proteins, featuring a basic structure that includes an amino group, a carboxyl group, a hydrogen atom, and a variable side chain (R group). Understanding the chemical composition and molecular formula of amino acids is important in biochemistry because it allows for the exploration of protein structure, function, and the metabolic pathways in living organisms.

Transcript

00:04 We have given information.

00:10 There are three carbon atoms, one nitrogen atom, one sulfur atom, two oxygen atoms, and seven hydrogen atoms.

00:57 Therefore, the molecular formula of cysteine is a system.

01:18 Is c3nso2h7 we have to find the percent composition by mass so the molar mass of 16 is sustain is we have formula to find molar mass is molar mass of c3 ns or 2 7 is equal to 3 into molar mass of carbon plus molar mass of nitrogen plus molar mass of sulfur plus 2 into molar mass of oxygen plus 7 into molar mass of hydrogen is equal to 3 into molar mass of carbon is 12 .011 gram per mole plus smaller mass of nitrogen is 14 .007 gram per mole plus smaller mass of sulfuris 32 .065 gram per mole plus smaller mass of oxygen is 2 into 15 .99 gram per mole plus 7 into molar mass of hydrogen is 1 .008 gram per mole is equal to we have the calculated molar mass of steam is 121 .159 gram per mole now we can find the mass percent composition.

05:13 So percent of carbon is equal to 3 into molar mass of carbon divided by molar mass of 16 c3ns o2h7, multiply 100 percent.

05:48 Is equal to 3 into 12 .011 gram per mole molar mass of carbon and molar mass of the compound system is 12 .159 gram per mole.

06:22 Multiply 100%.

06:26 Is equal to 29 .74%.

06:39 The mass percent composition of carbon in the compound is 29 .74%.

06:53 And next we have mass person composition of nitrogen is equal to mass of nitrogen, molar mass of nitrogen, divided by molar mass of 16 c3 c3n s -o2 -h7 multiply 100 % is equal to we have 14 .molar mass of nitrogen is 14 .007 gram per mole divided by molar mass of the compound is 121.

08:00 159 gram per mole multiply 100 % is equal to 11 .56%.

08:36 So the mass percent composition of nitrogen and the compound is 11 .56%...

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