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Answers to Questions Frequently Asked by Chemistry Students

Got questions about chemistry? Here are the answers to the most common questions I have been asked by chemistry students. These FAQs may help you with your homework or aid you in understanding chemistry concepts.

What Is the Importance of Chemistry?
What is the importance of chemistry? Why would you want to learn about chemistry? Chemistry is the study of matter and its interactions with other matter and energy. Here's a look at the importance of chemistry and why you should study it.

Who Was the First Chemist?
Chemistry has been around for a very long time! Do you know the name of the first chemist in recorded history? Would it surprise you that the first chemist was a woman?

Can I Teach Myself Chemistry?
You can teach yourself general chemistry with this step-by-step introduction to the basic concepts.

Chemistry Basics - What Is Chemistry?
Start learning chemistry with the basics. Learn what chemistry is, what chemists do, and why it's important to study chemistry.

Who Invented the Periodic Table?
Do you know who described the first periodic table of the elements that ordered the elements by increasing atomic weight and according to trends in their properties? I'll give you a hint. It was not Dmitri Mendeleev. The actual inventor of the periodic table is someone rarely mentioned in chemistry history books.

What Is the Difference Between a Scientist and an Engineer?
Scientist versus engineer: are they the same? Different? Here's a look at the definitions of scientist and engineer and the difference between a scientist and engineer.

What Are Elements?
What are elements? The chemical elements are central to the study of chemistry and other science. This is the definition of elements and an introduction to the elements.

What Is Chemical Engineering? What Do Chemical Engineers Do?
Are you confused about how chemical engineering differs from pure chemistry or other types of engineering? Here's an explanation of what chemical engineering is and what chemical engineers do.

How Do I Study Chemistry?
Here are some homework and study tips to help you succeed in chemistry.

What Is the Difference Between a Hypothesis, Theory, and Law?
Words have very specific meanings in chemistry and other sciences. Learn about the difference between a scientific law, hypothesis, and theory. Examples are provided for each term.

Can a Candle Burn in Zero Gravity?
Can a candle burn in the absence of gravity? Here's the answer to this frequently asked question about fire.

Can Hot Water Freeze Faster Than Cold Water?
Can hot water freeze faster than cold water? You may have heard this question and wondered how, if it's true, it could even be possible. Here's the answer to the question.

Does Hard Water Boil at a Higher Temperature?
Does hard water boil at a higher temperature than normal water? Here's the answer to the question and the explanation behind it.

Do You Add Sulfuric Acid to Water or Water to Sulfuric Acid?
It's important to add sulfuric acid to water and not water to concentrated sulfuric acid. Here's an explanation of why you don't want to make a mistake and some mnemonics that might help you remember how to play it safe in the chemistry lab.

How Are New Elements Discovered?
Find out if there are any elements left to be discovered and how they would be found.

How Can I Make My Own pH Paper?
You can make pH indicator from poinsettia flowers, then use the indicator to make your own pH paper test strips.

How Can I Test for Vitamin C?
Use this redox-based iodometric titration to determine the amount of Vitamin C or ascorbic acid in juice and other samples.

How Do Detergents Clean?
Learn about the chemistry behind the cleaning power of detergents.

How Do I Balance Equations?
A chemical equation describes what happens in a chemical reaction. It takes practice to be able to write balanced equations, but the process involves the same basic steps, no matter how complex the reaction. This tutorial guides you through the steps.

How Do I Balance Redox Reactions?
Get step-by-step instructions for balancing redox reactions for conservation of mass and charge in electrochemistry.

How Do I Calculate Concentration?
Do the units for solution concentration confuse you? Get definitions and examples for calculating percent composition by mass, mole fraction, molarity, molality, and normality. I've also included a bit of information on dilutions.

How Do I Clean Laboratory Glassware?
Cleaning laboratory glassware isn't as simple as washing the dishes. Here's how to wash your glassware so that you won't ruin your chemical solution, laboratory experiment, or the glass.

How Do I Dispose of Mercury?
Mercury is an extremely toxic metal that is found in fluorescent light bulbs, mercury thermometers, and other household items. If you break a thermometer or a mercury-containing bulb, it's important to dispose of the mercury properly so that you don't accidentally poison yourself or contaminate the area with mercury.

How Do I Do a Science Fair Project?
Science fair projects are a great way to learn about experimentation, the scientific method, and science concepts. However, it can be hard to find an idea or get answers to questions once you get started. Here is a collection of resources to give your project the winning edge.

How Do I Draw a Lewis or Electron Dot Structure?
Learn about Lewis structures, also called electron dot structures and get step-by-step help drawing them.

How Do I Fail a Chemistry Class?
Ok, so no one really needs to ask that. Avoid these mistakes to help ensure success in your chemistry class.

How Do I Grow a Seed Crystal?
A seed crystal is a small single crystal that you use to grow a much larger crystal from a saturated crystal solution. This is how you can grow a seed crystal yourself.

How Do I Make a Mixture? How Do I Make a Compound?
Do you know the difference between a mixture and a compound? Combine iron and sulfur to make a mixture and then react them to form a chemical compound.

How Do I Make a Smoke Bomb?
You can easily make a smoke bomb using inexpensive materials to produce safe smoke.

How Do I Make Disappearing Ink? How Does It Work?
Learn how to make blue or red ink that will disappear after exposure to air. Tips for restoring the color and an explanation of the acid-base chemistry of the reaction are also included.

How Do I Memorize the Order of the Elements?
Here's a handy mnemonic device to help memorize the symbols and sequence of the first nine elements in the periodic table.

How Do I Perform a Recrystallization?
Recrystallization is a laboratory technique used to purify a sample based on the different solubilites of its components. Learn how to perform a recrystallization and get tips on how to avoid common problems and improve your product yield.

How Do I Perform the Mohs Test?
The Mohs test is one way to determine the hardness of a rock or mineral. You can use the Mohs hardness to help identify an unknown specimen. Here's how you can do the test yourself.

How Do I Read a Meniscus?
The meniscus is the curve seen at the top of a liquid in response to its container. When you read a scale on the side of a container with a meniscus, such as a graduated cylinder or volumetric flask, it's important that the measurement accounts for the meniscus. Here's how to read a meniscus.

How Do I Take a Test?
How you take a test is at least as important as your preparation for it. These tips can help you make the grade.

How Do I Use Flash Cards?
Flash cards can be a great study aid. You can use them to help memorize facts, lists, and structures as well as to reinforce important concepts. Here's how to prepare and use flash cards to help study chemistry.

How Do I Write a Bibliography?
Learn how to cite your sources for a science fair project. See examples for books, online references, and conversations.

How Do I Write a Lab Report?
Lab reports are an essential part of all laboratory courses and usually a significant part of your grade. If your instructor gives you an outline for how to write a lab report, use that. Here's a format for a lab report you can use if you aren't sure what to write or need an explanation of what to include in the different parts of the report.

How Do I Write in Scientific Notation?
Scientific notation uses exponents to express numerical figures. Here's an explanation of what scientific notation is, plus examples of how to write numbers and perform addition, subtraction, multiplication and division problems using scientific notation.

How Do Mood Rings Work?
Mood rings have a stone that is supposed to change color to show your emotions. Do they work? If so, do you know how? Here's your chance to find out.

How Do Plants Make Food? How Photosynthesis Works
Photosynthesis is the name for the set of chemical reactions used by plants and other organisms to make food from sunlight, carbon dioxide, and water. Here's a look at the process and study questions to help make sure you understand the key concepts.

How Do Pregnancy Tests Work?
Learn how blood tests and home pregnancy urine tests work, how early they can be used, and some reasons for false positive and negative test results.

How Does Atomic Number Relate to Atomic Mass?
Higher atomic number doesn't imply higher atomic mass. At least not always! Sometimes one element of lower atomic number can have a higher atomic mass. Learn about the effect of isotopic ratios on atomic mass.

How Does Carbon 14 Dating Work?
Here's a worked example of the calculation for carbon 14 dating of organic material. The same principle can be applied to other isotopic ratios used to estimate age.

How Does Soap Clean?
You may use it every day, but do you know how it works? Learn about emulsions, micelles, and soap scum! Then check out links to sites about bubbles, soapmaking, and the regulation of soap chemistry.

How Is Aspirin Made?
Learn how to synthesize aspirin, acetylsalicylic acid, from salicyclic acid. Get information about the history of aspirin, the effects of salicylates, and see the structures of the reactants.

How Is the Water-into-Wine Demonstration Done?
Turn a clear liquid into a red liquid, then back to clear again. This demonstration is commonly called turning water into wine or blood, and can be used to demonstrate acid-base indicators.

Is Heavy Water Radioactive?
Heavy water contains deuterium, an isotope of hydrogen with a proton and a neutron for each deuterium atom. Is this a radioactive isotope? Is heavy water radioactive?

What Are Examples of Endothermic Reactions?
Are you looking for examples of endothermic reactions for homework or to set up a demonstration? Here's a list of several heat-absorbing or endothermic chemical reactions and processes.

What are Solutions, Suspensions, Colloids, and Dispersions?
Learn how to distiguish between solutions, suspensions, colloids, and dispersions. Get examples of the different types of mixtures.

What Are Some Careers in Chemistry?
Chemistry isn't just for chemists! Here's a nice long list of chemistry-related careers, along with a discussion on how your degree impacts your employment options.

What Are Some Chemistry Demos I Can Do?
This is the list of my personal favorite chemistry demonstrations and activities. They tend to involve pretty colors, fire, or ice. Some projects require adult supervision or access to a chemistry lab. Others are easy and safe enough for kids to perform.

What Are Some Examples of Atoms?
Atoms are fundamental units of matter that cannot be broken down using any chemical means. Here are some examples of atoms.

What Are Some Examples of Polymers?
Do you need some examples of polymers? Here is a list of materials that are polymers, plus some examples of materials that are not polymers.

What are the Chemistry Laboratory Safety Rules?
Make your chemistry laboratory experience safe by following these simple rules.

What Are the Elements in the Human Body?
Do you know the chemical composition of the human body? Here's the list of elements, given in percentage according to weight.

What Are the Names and Symbols of the Elements?
It's easier to navigate the periodic table and write chemical equations and formulae once you know the symbols for the elements. Here's an alphabetical list of element symbols with corresponding element names.

What Are the Periodic Properties of Elements?
The properties of the elements exhibit periodicity. Learn how to use the periodic table to predict the trends in atomic radius, ionization energy, electron affinity, and electronegativity.

What Are the States of Matter?
Get definitions and examples of the main states of matter: solids, liquids, gases, and plasma.

What Are the Uses of Food Additives?
This is a list of common food additives and a description of their uses.

Why Are Transition Metals Called Transition Metals?
Have you ever wondered where the transition elements got their name? It's not like they are a transition between nonmetals and metals or between one type of metal and another. Here's a look at the reason for the name.

What Do s, p, d, and f Mean?
s, p, d, and f are orbital names that stand for sharp, principal, diffuse, and fundamental. This summary tells more about orbitals and electronic structure.

What Elements Are In the Body and What Do They Do?
Find out what elements are in the human body and what these elements do.

What Happens If I Touch Dry Ice?
Dry ice is solid carbon dioxide, which is extremely cold. You should wear gloves or other protective gear when you handle dry ice, but have you ever wondered what would happen to your hand if you touched it? Here's the answer.

What Home Chemicals Shouldn't Be Mixed?
Labs have lists of chemicals that don't go together, but it isn't as easy to avoid dangerous mixtures with home chemicals because they aren't pure substances. Here's some help. Be safe and don't mix these common household chemicals.

What Is a CAS Number?
Many molecules are identified by a number following a CAS prefix. What are these CAS numbers and what do they mean?

What Is a Chemical?
Are you wondering what makes a chemical a chemical? Here's the answer to this frequently asked chemistry question.

What Is a Chemical Element?
Get the definition for a chemical element.

What Is a Crystal?
Get the definition for a crystal and learn about some common types of crystals.

What Is a Heavy Metal?
Find out what a heavy metal is and get examples of heavy metals.

What Is a Mixture?
You may have heard the term mixture used in reference to chemistry or cooking. Let's take a look at what a mixture is.

What Is a Mole and Why Are Moles Used?
No, we're not talking about the small burrowing mammal! Here's a look at a standard unit in chemistry and why it's used.

What is a Titration?
Grasp the basic chemical concepts of titration, a technique used to determine the molarity of an acid or a base.

What Is Absolute Zero?
Learn about absolute zero and the Kelvin and Celsius temperature scales.

What Is Activated Charcoal and How Does it Work?
Activated charcoal isn't the same as your average barbeque briquette! It's a special type of carbon. Learn what activated charcoal is and why it is used in filters and medicines.

What Is an Atom?
Are you confused about atoms, elements, protons, neutrons, electrons, isotopes, and ions? Here's a basic look at the model of the atom. It's a great overview for kids or anyone looking to grasp the essentials of atomic theory.

What Is Bleach and How Does It Work?
Learn what a bleach is, get examples of different types, and find out how bleach works.

What Is Chemistry?
Here are long and short answers to this Frequently Asked Question.

What Is Distillation?
Distillation is a common chemistry process used to separate materials by changing their states of matter. Learn more about how the process works and find out about different types of distillations.

What Is Fluoride?
Are you confused about the difference between fluoride and fluorine or simply want to know what fluoride is? Here's the answer to this common chemistry question.

What Is Mole Day? When Is Mole Day?
Have you heard about Mole Day? Here's a look at what Mole Day is, when Mole Day is observed, and what you can do to celebrate Mole Day.

What Is Protium?
What is protium? Here's the answer to this common science and element question.

What Is Radioactivity? What is Radiation?
Learn about natural and induced radioactivity and alpha, beta, and gamma radiation.

What Is Reverse Osmosis?
This handy technique is used to desalinate seawater and purify bottled water. Find out how it works!

What Is Soap and How Is it Made?
Soap is a salt made from a chemical reaction between fat and sodium or potassium hydroxide. This article explains the saponification reaction both in words and with structure diagrams and provides links for further information.

What Is the Difference between a Molecule and a Compound?
Molecules and compounds are two types of chemical species. Here is a look at the difference between a molecule and a compound.

What Is the Difference Between an Ionic and Covalent Chemical Bond?
Learn to distinguish between ionic and covalent bonds, and determine whether a bond will be polar or nonpolar.

What Is the Difference Between Baking Powder & Baking Soda?
Learn about the difference between these two common cooking ingredients, the effect of substitutions, and find out how you can use baking soda to make your own baking powder.

What Is the Difference Between Flammable and Inflammable?
Flammable and inflammable are two words that are commonly confusing. Learn what flammable and inflammable mean and whether they are synonyms or antonyms.

What Is the Difference Between Nuclear Fission and Fusion?
Nuclear fission and nuclear fusion both are nuclear phenomena that release large amounts of energy, but they are different processes which yield different products. Learn what nuclear fission and nuclear fusion are and how you can tell them apart.

What Is the Difference between Strong and Weak Acids and Bases?
Learn about strong and weak acids and bases. Get definitions and examples of each type.

What Is the IUPAC and What Does It Do?
Find out what the IUPAC is and learn a little about about what the IUPAC does.

What Is the Lightest or Least Dense Solid?
I'll give you a hint: it isn't styrofoam! The world's lightest solid resembles a sort of solid smoke, with a density of only 19 grams per liter.

What Is the Greenhouse Effect?
Learn what the greenhouse effect is and how it is related to climate.

What Is the Mohs Scale of Hardness?
The Mohs Scale of Hardness measures how well a substance resists scratching by another material. You can use this scale to test the hardness of rocks, minerals, and crystals, to help identify them.

What Is the Most Abundant Element?
The elemental composition of the universe and the earth's crust are very different! How different? Take a look...

What Is the Most Bitter Compound?
I've had some scorched coffee that I'm sure should have qualified for this award, but it turns out there's a real answer to this question of taste. Do you know what it is?

What Is the Most Poisonous Chemical Compound?
How poisonous something is depends a lot on how it's administered and a several other factors, but this list will give you a general look at some of the most toxic substances known to man.

What is the pH of a Common Chemical?
Here's a table of the pH of several common chemicals. You can use the list to set up color ranges for pH indicators or simply to learn more about acids and bases.

What Is the Scientific Method?
Science fair and research projects apply the scientific method. Here's an informal explanation of the scientific method and how it is used.

What Is the Smelliest Chemical?
There are some man-made chemicals with a stench well beyond the gentle perfume of dirty gym socks and skunk spray. Do you know the names of these super-stinkers?

What is the State of Matter of Fire?
What is the state of matter of fire or flame? Is it a liquid, solid, or gas? Learn the answer to this question and get information about the chemistry of fire.

What Is the Strongest Acid?
Do you know what the strongest acid is? I'll give you a hint. It's not hydrochloric acid nor is it sulfuric acid.

What Is the Sweetest Compound?
Did you know there are sweeteners that are 200,000 times sweeter than table sugar? Take a look at this list to find out how your favorite sweetener rates.

What Materials Glow Under a Black or Ultraviolet Light?
Black lights emit ultraviolet radiation, giving certain materials an eerie glow. Which materials? You can do a little experimental research or you can check out this list!

What Should I do with Returned Tests?
Learn why you should review a returned chemistry test and how to do it to gain the most benefit from the exam.

What Temperature Does Water Boil?
At what temperature does water boil? What determines the boiling point of water? Here's the answer to this common question.

Which Elements Are Named for People?
Alphabetical list of the chemical elements named after people.

Which Elements Are Named for Places?
Alphabetical list of elements in chemistry named for places or element toponyms.

Who Are Some Famous Chemists?
This is an index of famous chemists and other scientists who made important contributions to the field of chemistry, arranged alphabetically according to the scientist's last name.

Who Made Chemistry Discoveries? When?
Find out who did what and when they did it. This timeline chronicles achievements in chemistry and in other disciplines (e.g., physics, mathematics) as they apply to chemistry.

Why Are Phosphates Used in Cleaning?
Here's a question and answer from the About Chemistry forum.

Why Do a Science Fair Project?
There are excellent reasons why you would want to do a science fair project, even if it isn't for a grade.

Why Do Cut or Bruised Apples Turn Brown?
Learn why apples, pears, bananas, potatoes, and other fruits and vegetables turn brown when they are cut or damaged.

Why Do Onions Make You Cry?
Find out why you cry when you cut onions and how you can keep it from happening.

Why Do Students Fail Chemistry?
Worried about failing chemistry? Here's a look at the main reasons why students fail. Avoiding these common problems could be a key to science class success!

Why Does Ice Float?
Learn about hydrogen bonding and density to understand why ice floats on water.

Why Is lb the Symbol for Pounds?
Have you ever wondered why lb is used as the symbol for the pounds unit? Here's the answer to the question.

Why Is Stainless Steel Stainless?
Learn about the chemistry of stainless steel. This article, from your About Guide, also includes descriptions of the different types of stainless steels, comments on passivation, and numerous links to sites offering related information.

What Is a Chemical Equation?
Chemical Equation - What Is a Chemical Equation?

What Is the Shape of an Electron?
Electrons are too small to observe directly, but it's possible to determine their shape by watching how they influence chemical bonds. By observing the movement of electrons, scientists have been able to discern their shape.

What Is Tin Cry?
Learn about tin cry. Find out what tin cry is and why it occurs. Also, here is a demo in which you can make tin cry repeatedly.

What is the Difference Between Chemical Reaction and Chemical Equation?
What is the difference between a chemical reaction and the chemical equation? The terms are often used interchangeably, but they are technically different.

What Is Pitchblende?
Pitchblende is a mineral and the primary source of uranium.

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