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Know the Standard State Conditions Values of thermodynamic quantities are commonly expressed for standard state conditions, so it is a good idea to understand what the standard state conditions are. A superscript circle is used to denote a thermodynamic quantity that is under standard state conditions: ΔH = ΔH° ΔS = ΔS° ΔS = ΔS° Standard State Conditions Certain assumptions apply to standard state conditions. Standard temperature and pressure commonly is abbreviated as STP. The standard state temperature is 25°C (298 K). It is possible to calculate standard state values for other temperatures. All liquids are pure. The concentration of all solutions is 1 M (1 molar). All gases are pure. All gases are at 1 atm pressure. The energy of formation of an element in its normal state is defined as zer

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This is a collection of problem sets, lecture notes, articles, and labs for physical chemistry, thermochemistry, and thermodynamics. Laws of Thermochemistry Thermochemical equations are just like other balanced equations except they also specify the heat flow for the reaction. The heat flow is listed to the right of the equation using the symbol ΔH. The most common units are kilojoules, kJ. Here are two thermochemical equations: H2 (g) + ½ O2 (g) → H2O (l); ΔH = -285.8 kJ HgO (s) → Hg (l) + ½ O2 (g); ΔH = +90.7 kJ When you write thermochemical equations, be sure to keep the following points in mind: Coefficients refer to the number of moles. Thus, for the first equation, -282.8 kJ is the ΔH when 1 mol of H2O (l) is formed from 1 mol H2 (g) and ½ mol O2. Enthalpy changes for a phase change, so the enthalpy of a substance depends on whether is it is a solid, liquid, or gas. Be sure to specify the phase of the reactants and products using (s), (l), or (g) and be sure to look up the corre...

These are the structures for the twenty natural amino acids, plus the general structure for an amino acid.

If it isn't carbon-based, it's probably covered here. Of course, inorganic reactions of carbon are described, too. You'll find lecture and lab notes, molecular structures, journals, and study guides. Types of Inorganic Chemical Reactions Elements and compounds react with each other in numerous ways. Memorizing every type of reaction would be challenging and also unncecessary, since nearly every inorganic chemical reaction falls into one or more of four broad categories. Combination Reactions Two or more reactants form one product in a combination reaction. An example of a combination reaction is the formation of sulfur dioxide when sulfur is burned in air: S (s) + O2 (g) --> SO2 (g) Decomposition Reactions In a decomposition reaction, a compound breaks down into two or more substances. Decomposition usually results from electrolysis or heating. An example of a decomposition reaction is the breakdown of mercury (II) oxide into its component elements. 2HgO (s) + heat --...

Citric Acid Cycle - Overview of the Citric Acid Cycle The Citric Acid Cycle is also known as the Krebs Cycle or Tricarboxylic Acid (TCA) Cycle. It is a series of chemical reactions that takes place in the cell that breaks down food molecules into carbon dioxide, water, and energy. Narayanese, wikipedia.org The citric acid cycle, also known as the Krebs cycle or tricarboxylic acid (TCA) cycle, is a series of chemical reactions in the cell that breaks down food molecules into carbon dioxide, water, and energy. In plants and animals, these reactions take place in the mitochondria of the cell as part of cellular respiration. Many bacteria perform the citric acid cycle too, though they do not have mitochondria so the reactions take place in the cytoplasm of bacterial cells. Sir Hans Adolf Krebs, a British biochemist, is credited with discovering the cycle. Sir Krebs outlined the steps of the cycle in 1937. The overall reaction for the citric acid cycle is: Acetyl-CoA + 3 NAD+ + Q + GDP + P...

This chemistry glossary offers definitions for terms which are commonly used in chemistry and chemical engineering. An engineering glossary is available, too. abrasive absolute error absolute pressure absolute temperature absolute uncertainty absolute zero absorbance absorption absorption cross section absorption spectroscopy absorption spectrum absorptivity accelerator accuracy acetate acid acid anhydride acid-base titration acid dissociation constant - Ka acidic solution actinides activated complex activation energy - Ea actual yield addition polymer addition reaction adhesive adsorption aerosol alchemy alcohol aldehyde alkali metal alkaline alkaline earth metal alkane alkene alkyl group alkyne allotrope alloy alpha particle alternating copolymer ammeter amorphous analytical chemistry anion androgen anisotropy annealing antiferromagnetism antioxidant aromatic compound aqueous solution Arrhenius rate equation astrochemistry atactic atom atomic mass atomic mass unit (amu) atomic num...

Soap is good at cleaning because it acts as an emulsifier, enabling one liquid to disperse into another immiscible liquid. While oil (which attracts dirt) doesn't naturally mix with water, soap can suspend oil/dirt in such a way that it can be removed. It's easy to demonstrate the action of an emulsifer. All you need are two immiscible liquids and a little dishwashing detergent or soap. Emulsifier Demo Materials water kerosene or oil dishwashing detergent or soap flask or clear glass Perform the Demonstration Add some kerosene or oil together with some water in a flask. Swirl the contents around to try to mix them. What happens? Add a squirt of dishwashing liquid. Swirl or shake the flask to mix the ingredients. How has the layer of kerosene or oil been changed? What could be easier, right?

As silver oxidizes it will tarnish. This layer of oxidation can be removed without polishing and scrubbing by simply dipping your silver in this non-toxic electrochemical dip. Another big advantage to using a dip is that the liquid can reach places a polishing cloth cannot. You can use chemistry to removethe tarnish from your silver without even touching it. Mel Curtis, Getty Image Difficulty: Easy Time Required: Minutes Here's How: Line the bottom of the sink or a glass baking dish with a sheet of aluminum foil. Fill the foil-lined container with steaming hot water. Add salt (sodium chloride) and baking soda (sodium bicarbonate) to the water. Some recipes call for 2 tsp baking soda and 1 tsp salt, whereas others call for 2 tablespoons each of baking soda and salt. Personally, I wouldn't measure the amounts... just add a bit of each substance. Drop the silver items into the container so that they are touching each other and resting on the foil. You will be able to watch the ta...

Here's a cute cartoon to brighten your day. Sulfur pentafluoride presumably binds with itself to make disulfur decafluoride, a chemical warfare pulmonary agent similar to your good old friend phosgene . Fun stuff. Disulfur decafluoride eventually decomposes into sulfur hexafluoride (which can be used as a sort of anti-helium in gas density demonstrations ) and sulfur tetrafluoride (which reacts with moisture in the air to form sulfurous acid and hydrofluoric acid). Incidentally, while I have no idea about the color of sulfur pentafluoride, I can tell you disulfur decafluoride is colorless and one breath can kill you in a day. It takes a while because its actually the acids produced by the sulfur tetrafluoride reacting with water that likely do you in.

One of my self-improvement projects has been to try to learn how to write legibly. It would be easy to blame my handwriting on being left-handed, but it probably has a lot more to do with trying to write quickly rather than neatly. So, I got a pen and some ink and have been practicing. Ink is one of the practical contributions of chemistry. You can make invisible inks and tattoo inks in addition to writing and drawing inks. Although ink recipes may be closely-guarded secrets, the basic principles of preparing ink are simple. You want to mix a pigment with a carrier (usually water). It helps to include a chemical which will allow the ink to flow fluidly and adhere to the paper (gum arabic). Here are some easy ink recipes to get you started ma Black Permanent Ink 1/2 tsp lamp black (which you can buy or can make by holding a plate over a candle and collecting the soot or from collecting other char) 1 egg yolk 1 tsp gum arabic 1/2 cup honey Mix together the egg yolk, gum arabic, and ho...

Here's an easy and colorful chemistry demonstration for you. Take a long glass tube and fill it with Universal Indicator solution. Add a few drops of 0.02M HCl to one end of the tube and seal it with a stopper. Add a couple of drops of 0.02M NaOH to the other end of the tube and seal it. The Universal Indicator will respond to the pH gradient by providing you with a lovely rainbow. You can invert the tube a few times to speed things up. You can get a similar result using home chemistry. Fill a clear straw with red cabbage juice . Add a little lemon juice or vinegar to one end of the straw. Add a few drops of baking soda or laundry detergent solution to the other end of the straw.

November 13 th is Edward Doisy's birthday. Doisy was an American biochemist who shared the 1943 Nobel Prize in Medicine with Henrik Dam for their work concerning vitamin K. Dam discovered the vitamin and Doisy identified, isolated, determined the structures, and synthesized of two different forms of vitamin K. Vitamin K is actually a group of vitamins named after "Koagulations-Vitamin" in German because they are required for processes of blood coagulation. They are also involved in the process of binding calcium during bone metabolism. Deficiency is rare in adults, but newborns have a higher risk, and an injection of vitamin K1 is recommended by the American Academy of Pediatrics shortly after birth. Other research into the K vitamins is looking at links between vitamin K and bone health, Alzheimer's disease, and certain cancers.

Three of my children have birthdays in November, so I've already got a jump on holiday shopping ideas. I have a few different gift lists that I use to jog my memory when I need ideas. Top Science Toys is an all-inclusive collection of fun and educational science toys and gadgets. I also have a list of gifts you can make by applying your command of chemistry. This year I've added a new list to the collection: Chemistry Gift Ideas. These are gifts someone with a love of chemistry would especially enjoy. With the possible exception of a chemical volcano, chemistry gifts are a little harder to find in stores than other gifts. Most of the online retailers offer overnight shipping so even if you wait until the last minute for your holiday shopping, you'll still find the perfect present!

A plasma ball is one of the cool items that made my Top Science Toys list.

A diamond crystal is a form of elemental carbon. USGS

Oxygen 65% of Body Weight Oxygen is present in water and other compounds. Liquid oxygen in an unsilvered dewar flask. Liquid oxygen is blue. Warwick Hillier, Australia National University, Canberra Oxygen is necessary for respiration. You will find this element in the lungs, since about 20% of the air you breathe is oxygen.

99% of the mass of the human body is made up of only six elements: oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus. Every organic molecule contains carbon. Since 65-90% of each body cell consists of water (by weight), it isn't surprising that oxygen and hydrogen are major components of the body. Here's is a look at the major elements in the body and what these elements do. Carbon Carbon is found in every organic molecule in the body. Photograph of graphite, one of the forms of elemental carbon. U.S. Geological Survey Carbon is ingested in food that is eaten and breathed in as a component of air. It is found in the lungs as a waste product of respiration, carbon dioxide.

The Chemical Basis for Life Carbon is the basis for organic chemistry , as it occurs in all living organisms. Carbon is a nonmetal that can bond with itself and many other chemical elements , forming nearly ten million compounds . Elemental carbon can take the form of one of the hardest substances (diamond) or one of the softest (graphite). Carbon is made in the interiors of stars, though it was not produced in the Big Bang. Carbon compounds have limitless uses. In its elemental form, diamond is a gemstone and used for drilling/cutting; graphite is used in pencils, as a lubricant, and to protect against rust; while charcoal is used to remove toxins, tastes, and odors. The isotope Carbon-14 is used in radiocarbon dating. Carbon has the highest melting/sublimation point of the elements. The melting point of diamond is ~3550°C, with the sublimation point of carbon around 3800°C. Pure carbon exists free in nature and has been known since prehistoric time. The origin of the name 'carbo...

Chemistry of Carbohydrates Carbohydrates or saccharides are the most abundant class of biomolecules. Carbohydrates are used to store energy, though they serve other important functions as well. This is an overview of carbohydrate chemistry, including a look at the types of carbohydrates, their functions, and carbohydrate classification. What Is a Carbohydrate? Carbohydrates are a common class of simple organic compouds. A carbohydrate is an aldehyde or a ketone that has additional hydroxyl groups. The simplest carbohydrates are called monosaccharides, which has the basic structure (C·H2O)n, where n is three or greater. Monosaccharides link together to form oligosaccharides and polysaccharides. Two monosaccharides link together to form a disaccharide. Functions of CarbohydratesCarbohydrates serve several biochemical functions: Monosaccharides are a fuel for celular metabolism. Monosaccharides are used in several biosynthesis reactions. Monosaccharides may be converted into space-saving ...

Introductory Stoichiometry A chemical equation describes what happens in a chemical reaction . The equation identifies the reactants (starting materials) and products (resulting substance), the formulas of the participants, the phases of the participants (solid, liquid, gas), and the amount of each substance. Balancing a chemical equation refers to establishing the mathematical relationship between the quantity of reactants and products. The quantities are expressed as grams or moles. It takes practice to be able to write balanced equations . There are essentially three steps to the process: Write the unbalanced equation. Chemical formulas of reactants are listed on the lefthand side of the equation. Products are listed on the righthand side of the equation. Reactants and products are separated by putting an arrow between them to show the direction of the reaction. Reactions at equilibrium will have arrows facing both directions. Balance the equation. Apply the Law of Conservation of...

Tin oxide is heated with hydrogen gas to form tin metal and water vapor. Write the balanced equation that describes this reaction. Write the unbalanced equation. SnO2 + H2 → Sn + H2O Refer to Table of Common Polyatomic Ions and Formulas of Ionic Compounds if you have trouble writing the chemical formulas of the products and reactants. Balance the equation. Look at the equation and see which elements are not balanced. In this case, there are two oxygen atoms on the lefthand side of the equation and only one on the righthand side. Correct this by putting a coefficient of 2 in front of water: SnO2 + H2 → Sn + 2 H2O This puts the hydrogen atoms out of balance. Now there are two hydrogen atoms on the left and four hydrogen atoms on the right. To get four hydrogen atoms on the right, add a coefficient of 2 for the hydrogen gas. Remember, coefficients are multipliers, so if we write 2 H2O it denotes 2x2=4 hydrogen atoms and 2x1=2 oxygen atoms. SnO2 + 2 H2 → Sn + 2 H2O The equation is...