The most common monosaccharides, glucose, fructose and galactose, have either five or six carbon atoms. The presence of many polar groups makes these monosaccharides water soluble.
Glucose is a six carbon sugar that has an aldehyde structure. Glucose is often called blood sugar as it is present in the blood at high concentration.
It serves as major source of immediate energy. Fructose is a six carbon sugar with ketone structure. Fructose is known as fruit sugar as it is present in many fruits. Glucose and fructose are structural isomers, structurally different with same molecular formula 6. Galactose is a stereo isomer of glucose. They differ in special arrangement of hydrogen atom and hydroxyl group around one of the six carbon atoms.
A disaccharide is formed when two monosaccharides are bonded together via a condensation reaction with the release of a water molecule. Sucrose and lactose are common disaccharides. Sucrose is also known as table sugar as it is mainly used as a sweetener. Sucrose is formed from glucose and fructose.
Lactose is often called as milk sugar as it is important carbohydrate in milk. Lactose is formed from glucose and galactose is bonded together. After ingestion, disaccharides are too large to be absorbed into the blood stream directly, so the digestive enzymes sucrase and lactase break sucrose and lactose respectively into their monosaccharide units. Polysaccharides contain 12 or more monosaccharide units bonded together.
These are often termed complex sugars. Starch, glycogen and cellulose are important polysaccharides. Plants make starch and cellulose: starch is water soluble where as cellulose is insoluble. The animal counterpart of starch is a different polysacchride called glycogen. It is made by animals to store energy, mostly in muscles and liver. Glucose is the monomer for each of these three polymers. Although they have same monomer unit, they have different properties.
This is because of the way the glucose monomers are bonded differ in the three polysacchrides. Cellulose has a linear structure which resembles a chain like fence.
Starch molecules are either branched or unbranched, and glycogen is highly branched. Due to the difference in their bond shape, humans can digest starch and glycogen but not cellulose. Digestive enzymes can't fit cellulose into their active sites due to the specific lock and key fit needed for enzyme action. As a result, the cellulose in the fruits, vegetables, and grains that we eat passes through the digestive system without being changed or absorbed.
Molecules that behave like this are called dietary fiber. The main function of carbohydrates is as a source of energy, both immediate and stored. When carbohydrates are oxidized they release carbon dioxide, water and energy. Foods that are rich sources of carbohydrates include bread, rice, pasta, potatoes, milk, pie, soft drinks, vegetables, fruits etc 7. Because of the difference in the composition of the carbohydrates in each of these foods, their short and long-term effects on energy in the body differ.
Eating whole grain products helps the body's sugar control system 8. Insulin, which is produced by pancreatic beta cells, is secreted into the blood circulation in response to the rise in blood glucose after meals. Insulin regulates blood glucose levels by suppressing glucose production from the liver and stimulating glucose uptake by cells throughout the body.
When glucose or other simple sugars are eaten directly, blood sugar and therefore insulin rises dramatically. The fiber in whole grains leads to a slower rise in blood glucose and eases the workload for the insulin making cells in the pancreas 9.
Diabetes occurs when the pancreas is unable to secrete insulin—or cells in the body stop responding to insulin. The word protein came from the Greek root word protos , which means first Proteins are organic polymers made of amino acids linked together in a specific way.
Each amino acid has a carboxyl and an amino group. The amino and carboxyl groups provide convenient bonding sites for linking amino acids together. The amide bond that joins two amino acids is known as a peptide bond.
Proteins are not just large molecules but also randomly arranged chains of amino acids. There are 20 amino acids, which make up the tens of thousands of different proteins in our body. Our body makes some of these amino acids and rest are obtained from food. These amino acids are referred as essential amino acids as they are essential in the diet.
Proteins are the building blocks of the body. Proteins play many roles in our body. Proteins are involved in forming structures, digesting foods, catalyzing reactions, transporting substances, regulating cellular processes, recycling wastes, and even serving as an energy source when other sources are scarce.
For example, insulin is a protein hormone, a small protein with 51 amino acids. The recommended daily allowance of protein is 50 grams a day for a pound person and almost 65 grams for a pound person Common sources of protein are meat, milk, nuts, fish, and some fruits and vegetables.
Protein is found in the body in high concentrations in muscle, hair, skin, bone and all other tissues. The effects of dietary proteins on health probably are approximately the same for animal protein and plant protein. Animal proteins tend to be complete, as they are sources of all essential amino acids. However one must be careful about eating too much of it, as animal protein tends to come with saturated fat.
Though vegetable proteins are incomplete, that is, they do not have all essential amino acids, but still they are good source of proteins. Research says that eating a lot of protein does not harm the heart Choosing the right protein sources that are low in saturated fat will help you keep in good health. Fats are large, non polar, biological molecules. Fats are insoluble in water as they are non polar.
Fats have two major functions in living organisms. They store energy efficiently, and they make up most of the structure of cel1 membranes. Fats are convenient source of energy storage. Our dietary fat contains phospholipids, and cholesterol in addition to triglycerides.
A triglyceride is formed by condensation of one molecule of glycerol with three molecules of fatty acid. Animal and vegetable fats are complex mixtures of triglycerides. The cell membrane is made up of phospholipids that regulate transportation of substances across the cell membrane. Our body requires cholesterol to make estrogen, testosterone and other vital compounds. There are four types of fatty acids: monounsaturated, polyunsaturated, saturated and trans. All fatty acids are long chain hydrocarbons.
Unsaturated fatty acids contain double bonds between some of the carbon atoms. Depending on the number of double bonds, the fatty acid can be monounsaturated one double bond or polyunsaturated more than one double bond. Due to the cis orientation of double bonds naturally occurring in unsaturated fatty acids, they have a kink or bend that prevents them from packing together efficiently.
This results in less intermolecular attractions, and lower melting points. Unsaturated fatty acids are in liquid phase at room temperature.
These fatty acids are termed as good fats because eating these fats instead saturated fats and carbohydrates lowers levels of low-density lipoprotein bad cholesterol with out lowering the levels HDL good or protective cholesterol.
Olive oil, vegetable oil, and fish oils are rich in unsaturated fats. Saturated fatty acids do not contain double bonds hence they are saturated with hydrogen.
Saturated fatty acids can pack together due to their straight chain structure. Saturated fatty acids have higher melting points, hence they are in solid form at room temperature.
Whole milk, red meat, and coconut oil are good sources of saturated fats. These fats are termed as bad fats as they strongly increase the LDL bad cholesterol Hydrogenation, addition of hydrogen, to unsaturated fatty acids yields saturated fatty acids. For example, oleic acid can be hydrogenated to form stearic acid. Trans fats are mostly man made fats. Polyunsaturated fatty acids upon partial hydrogenation yield trans acids.
During this process, hydrogen will be added on to double bonded carbons, but not all, to create single bonds. At the same time, some of the remaining double bonds change their orientation, from cis to trans, resulting in new physical and chemical properties to fats. Like saturated fats, trans fats increase the LDL cholesterol. They also elevate the triglycerides and lipoproteins.
A higher level of these in the blood stream increases the chances of heart disease. This does not happen with saturated fats. This indicates that trans fats are more dangerous than saturated fats. Vegetable shortenings, most margarine, deep fried fast food, most commercially baked foods, and partially hydrogenated vegetable oil 14 are sources of trans fat.
Including the good fats in the diet and keeping away the bad fats keeps a person healthy. Most importantly, keep trans fats out of your meal. The Law of Conservation of Mass states that 'the mass of the universe is constant'. This means that mass is neither created nor destroyed. According to the Law of Conservation of Mass, one has to balance every chemical equation so that the mass of substances remain the same before and after the chemical change.
Another way of stating this, which is more convenient for chemists, is: all atoms present in the reactants must be accounted for among the products. A balanced equation gives the relative numbers of reactants and product molecules. As mentioned earlier, in our body several chemical reactions take place during digestion, respiration and other processes. Some examples of biochemical reactions:.
Example1: During cellular respiration, our cells make energy from the breaking down of glucose by oxygen into carbon dioxide and water. The process is an exothermic process, the energy releasing process. Example 3: Peptides are synthesized by coupling of carboxylic group of one amino acid with amino group of another amino acid to form peptide bond. A fraction of chemical reactions that occur in our body during metabolism, cellular respiration, and protein synthesis is mentioned above to show the importance of chemistry in understanding the metabolism, and our food.
We are all familiar with measuring the quantity of substances by their mass: I have one pound of oranges or 10 grams of gold. But there is another way of measuring amounts that is convenient for chemists, or anyone interested in substances that can react. A mole is a unit of measure equal to the number of carbon atoms in exactly 12 grams of pure Carbon A mole of any other substance is this same number of units of that substance.
One mole of any substance contains Avogadro's number of units of that substance. Avogadro's number has been determined experimentally to be 6. The molar mass of a compound is the mass in grams of one mole of the compound and is computed by summing the average masses of its constituent atoms. As I mentioned in the rationale, a stoichiometry problem requires the understanding the mole concept, molar mass, balancing equations, and conversions. As a mole is such a big number, I use Mole Facts 16 to fascinate my students.
Some of the mole facts are listed here:. Stoichiometry from the Greek stoicheion , element, and metria , science of measurement 17 deals with the calculation of the quantities of material consumed and produced in chemical reactions.
It is like chemical arithmetic. Stoichiometry is used in industry quite often to determine the amount of materials required to produce the desired amount of products in a given useful equation. Stoichiometry calculations help scientists and engineers working in industry to estimate the amount of products they will obtain from a given procedure: it can also help decide whether the product is profitable to produce or not.
Companies make many chemical substances, through chemical reactions, that are helpful in our lives. For example, addition of stannous fluoride, SnF 2 , to tooth paste to prevent the tooth decay in tooth paste industry; aspartame, a sugar substitute, in soft drinks in soft drink industry; preparation of citric acid from the fermentation of sugars sucrose in air in food industry; synthesis of aspirin in pharmaceutical industry; use of titanium metal and its alloys in aerospace industry; extraction of titanium from its ore rutile, TiO 2 , in metallurgy; production of the bleaching agent, calcium hypochlorite, from sodium hydroxide, calcium hydroxide, and chlorine in detergent industry; manufacture of polyethylene which is found in some milk cartons in polymer industry; removal of dangerous mercury compounds from industrial waste in environmental chemistry.
The list could go on. We can get rid of the fractional coefficients by multiplying by 2 even though this is a perfectly acceptable balanced chemical equation. At the very beginning of this problem, perhaps you could see this was the answer. If you can see the balanced equation by sight, you don't need to go by the guidelines.
Remember they are only guidelines to help if you run into trouble. You can see by simply adding a 2 in front of NO, we violate the first guideline even though it leads us to a balanced equation.
How is stoichiometry used in everyday life? What is stoichiometry and why is it useful? How do you explain stoichiometry to a child? How is stoichiometry used in industry? Why is it important to know stoichiometry? How is stoichiometry similar to cooking? What is the scientific reason of how stoichiometry is used in cooking?
How is a balanced equation similar to a recipe? What is a stoichiometric mixture? What is a rich mixture? What air-fuel ratio is best for power? Which is better lean or rich mixture? Stoichiometry and Balanced Equations In stoichiometry, balanced equations make it possible to compare different elements through the stoichiometric factor discussed earlier. Example 2 There are 12 party invitations and 20 stamps.
Based on this, we have the ratio of 2 stamps for 1 sent invite, based on the balanced equation. Invitations Stamps Party Invitations Sent In this example are all the reactants stamps and invitations used up? Example 3 What is the limiting reagent in this example?
Solution Stamps, because there was only enough to send out invitations, whereas there were enough invitations for 12 complete party invitations. Types of Reactions There are 6 basic types of reactions. Combustion : Combustion is the formation of CO 2 and H 2 O from the reaction of a chemical and O 2 Combination synthesis : Combination is the addition of 2 or more simple reactants to form a complex product.
Decomposition: Decomposition is when complex reactants are broken down into simpler products. Single Displacement : Single displacement is when an element from on reactant switches with an element of the other to form two new reactants.
Double Displacement: Double displacement is when two elements from on reactants switched with two elements of the other to form two new reactants. Acid-Base: Acid- base reactions are when two reactants form salts and water. Molar Mass Before applying stoichiometric factors to chemical equations, you need to understand molar mass. For compounds or molecules, you have to take the sum of the atomic mass times the number of each atom in order to determine the molar mass Example 4 What is the molar mass of H 2 O?
Step 3: Convert Variation in Stoichiometric Equations Almost every quantitative relationship can be converted into a ratio that can be useful in data analysis.
Percent Mass Percents establish a relationship as well. Example 7 How much 5 M stock solution is needed to prepare mL of 2 M solution? Determining Empirical Formulas An empirical formula can be determined through chemical stoichiometry by determining which elements are present in the molecule and in what ratio.
Example 8: Combustion of Organic Molecules 1. Solution This is a combustion reaction. Moles of oxygen in CO 2 : 0. Determining Molecular Formulas To determine a molecular formula, first determine the empirical formula for the compound as shown in the section above and then determine the molecular mass experimentally.
Example 9 In the example above, it was determined that the unknown molecule had an empirical formula of CH 2 O. Find the molar mass of the empircal formula CH 2 O. Determine the molecular mass experimentally. For our compound, it is Divide the experimentally determined molecular mass by the mass of the empirical formula.
Solution Step 1 : Write a balanced equation after determining the products and reactants. Problems Stoichiometry and balanced equations make it possible to use one piece of information to calculate another.
Weblinks for further reference 1. References T. Brown, H. E LeMay, B. Bursten, C. Chemistry: The Central Science. Prentice Hall, January 8,
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