If an organic compound has its hydrogen: oxygen ratio as 2:1, it is likely to be
A. a protein
B. a cabohydrate
C. a fat
D. a fatty acid and glycerol
Correct Answer:B
Explanation
The correct option is B. a carbohydrate.
Detailed Explanation:
Understanding the Ratio: The question states that the organic compound has a hydrogen to oxygen ratio of 2:1. This is a key characteristic of carbohydrates. In chemistry, carbohydrates are defined as organic compounds that typically have the general formula ( C_n(H_2O)_n ), where ( n ) is the number of carbon atoms. This formula indicates that for every carbon atom, there are two hydrogen atoms and one oxygen atom, which simplifies to a hydrogen to oxygen ratio of 2:1.
Carbohydrates: Carbohydrates are primarily composed of carbon (C), hydrogen (H), and oxygen (O). They can be classified into three main categories:
Monosaccharides: Simple sugars like glucose and fructose, which have the basic formula ( C_6H_{12}O_6 ).
Disaccharides: Composed of two monosaccharides, such as sucrose (table sugar), which has the formula ( C_{12}H_{22}O_{11} ).
Polysaccharides: Long chains of monosaccharide units, such as starch and cellulose.
Why Other Options Are Incorrect:
A. a protein: Proteins are made up of amino acids, which contain carbon, hydrogen, oxygen, and nitrogen. The ratio of hydrogen to oxygen in proteins is not fixed at 2:1; it varies depending on the specific amino acids involved. Therefore, this option does not fit the given ratio.
C. a fat: Fats, or lipids, typically have a much higher ratio of hydrogen to oxygen than 2:1. For example, triglycerides (the main constituents of body fat in humans and animals) have a general formula of ( C_nH_{2n}O_3 ), which results in a hydrogen to oxygen ratio greater than 2:1. Thus, this option is also incorrect.
D. a fatty acid and glycerol: Fatty acids and glycerol are components of fats. Fatty acids have a long hydrocarbon chain and a carboxylic acid group, and they also do not maintain a 2:1 hydrogen to oxygen ratio. Glycerol, a three-carbon alcohol, has a different composition as well. Therefore, this option does not match the specified ratio.
Summary of Key Points:
The hydrogen to oxygen ratio of 2:1 is characteristic of carbohydrates.
Carbohydrates include monosaccharides, disaccharides, and polysaccharides, all adhering to the ( C_n(H_2O)_n ) formula.
Proteins, fats, and fatty acids do not conform to the 2:1 ratio, making them incorrect options.
Understanding the basic structures and formulas of organic compounds is crucial for identifying their classifications.
Revision Summary:
Carbohydrates have a hydrogen to oxygen ratio of 2:1.
The general formula for carbohydrates is ( C_n(H_2O)_n ).
Proteins and fats do not fit the 2:1 ratio due to their different compositions.
Familiarity with organic compound structures aids in classification and identification.