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experimental procedure
what's happening
Iron is a crucial component of a balanced diet (there should actually be enough iron in your body to make one or two small nails), but some people might not consume enough iron naturally to sustain themselves. Because of this, many food manufacturers add iron to some foods to boost the average daily intake of this important mineral. Some foods may use a chemical form like ferric orthophosphate (FePO4) or ferrous sulfate (FeSO4), but most cereals simply use elemental (i.e. the pure atom) iron (Fe), also called "Reduced Iron".
The iron you see in your cereal is elemental iron- actual metallic iron filings or shavings similar to the little flakes you might see come off of a steel wool pad when you squeeze or rub it, just much smaller. That's right, you're eating metal in the morning! But not to worry, acids in your digestive tract can change this metallic iron into a form that is easily absorbed and used by your body. [Note: if you don't see any iron particles in this experiment you probably have a cereal that add one of the chemical forms listed above, so try a different cereal instead.] These very tiny metal particles are mixed into the rest of the cereal ingredients, which is why you don't normally see them, but a magnet will attract these small iron filings that are present in the cereal, separating them from the other cereal components which are not attracted to the magnet (there's more information about magnetism in the reference links below). Crushing the cereal and mixing it with water makes it much easier to separate the iron. By the way, this is also why you need to use a wooden popsicle stick or plastic spoon to stir in Step 8 of the procedure above (if your cup doesn't have a lid). Most metal spoons are made of steel, which contains a lot of iron and therefore will also be attracted to your magnet (although some types of steel are actually not very magnetic at all). Separating iron from cereal requires a powerful magnetic field, which is why we need to use a strong neodymium magnet, which is actually made from the elements neodymium, iron and boron (Nd2Fe14B). Neodymium is rarely found in nature, so these magnets are sometimes called Rare Earth magnets. Neodymium magnets are usually plated with a thin layer of another metal like nickel so they look like they're metal, but they are actually a type of ceramic. Ceramic materials are similar to glass, so these magnets are fragile and can shatter or break quite easily, often producing sharp edges, if you allow them to slam together. Because of this as well as their strength they must be handled very carefully. Some breakfast cereals contain much more iron that other cereals. You can find out how much iron any cereal contains by reading the "Nutrition Facts" labels on the side of the box (like the photo above). For example, "Total" cereal contains 100% of the recommended daily iron allowance, while "Shredded Wheat" contains only 8% - this is why you should see more iron filings from the Total cereal. Test several different cereals, does the amount of iron you see agree with the information on the labels? Is it important that you use the same amount of each cereal and shake it for the same length of time? Is it important to use the same amount of water? Why or why not?
variations and related activities
After you have separated the iron from the cereal and water mix and rinsed the cup with water, carefully remove the magnet from the bottom of the cup. Be sure not to tip the cup as once the magnet is removed the iron particles will be free to move. Add a little bit of water to the cup and gently stir or swirl the cup to mix the iron particles. Now hold the magnet near the sides or bottom of the cup and observe how the tiny iron particles move. Try holding the magnet in different positions. How does this affect the movement and orientation of the iron particles? If you're careful you may be able to observe the shape of the magnetic field lines that surround the magnet. You can also try this with a little bit of vegetable or baby oil instead of water in the cup [first tape the magnet to the bottom of the cup again to attract and pin all the iron, then carefully dump out the water and gently dry the cup without disturbing the iron particles, then add the oil]. How does the oil affect the motion of the iron particles?
If you hold your magnet near a flake of piece of the cereal, does it move? What if you crush the cereal into smaller pieces? Try floating a piece of cereal in a bowl of water, then holding the magnet very close. Does it move now? Another way to do this experiment is to place your magnet inside a small balloon, squeeze out any air inside, then tie it. Now simply drop the balloon into your bowl of mashed cereal and water mixture, attach the lid and shake several minutes as before. Open the lid, remove the balloon and rinse it with water to see the iron filings stuck to the balloon. If you want to try another cool science experiment with your left over cereal (although it has nothing to do with iron or metal), check out the "Cheerios Effect" (see reference link below). As the name suggests, it works best with Cheerios, but try it with other cereals too.
References and links to more information
Other variations of this experiment:
Why iron is so important for your body:
Which breakfast cereals have the most iron:
Iron and magnetism (ferromagnetism):
Magnetic field lines: The Cheerios Effect (and how it affects bugs that walk on water):
¡Hay metal en mi cereal! (en español)
Los metales como el hierro y el acero se utilizan para fabricar automóviles, barcos y clavos. Es posible que también haya escuchado que necesita alimentos ricos en hierro en su dieta para una buena salud; la deficiencia de hierro puede provocar enfermedades como la anemia. Pero tal vez nunca se dio cuenta de que en realidad es el mismo hierro en cada caso. Así es, estás comiendo exactamente lo mismo que se encuentra en las uñas todos los días, ¡y en este experimento lo verás por ti mismo!
Lo que necesitarás
Procedimiento experimental
QUÉ ESTA PASANDO
El hierro es un componente crucial de una dieta equilibrada (en realidad, debería haber suficiente hierro en su cuerpo para hacer una o dos uñas pequeñas), pero es posible que algunas personas no consuman suficiente hierro de forma natural para mantenerse. Debido a esto, muchos fabricantes de alimentos agregan hierro a algunos alimentos para aumentar la ingesta diaria promedio de este importante mineral. Algunos alimentos pueden usar una forma química como el ortofosfato férrico (FePO4) o el sulfato ferroso (FeSO4), pero la mayoría de los cereales simplemente usan hierro (Fe) elemental (es decir, el átomo puro), también llamado "Hierro reducido".
El hierro que ve en su cereal es hierro elemental, limaduras o virutas de hierro metálico reales similares a las pequeñas escamas que puede ver salir de una almohadilla de lana de acero cuando la aprieta o frota, pero mucho más pequeñas. Así es, ¡estás comiendo metal por la mañana! Pero no se preocupe, los ácidos en su tracto digestivo pueden cambiar este hierro metálico a una forma que su cuerpo absorbe y utiliza fácilmente. [Nota: si no ve ninguna partícula de hierro en este experimento, probablemente tenga un cereal que agregue una de las formas químicas mencionadas anteriormente, así que pruebe con un cereal diferente en su lugar.] Estas diminutas partículas de metal se mezclan con el resto del ingredientes de los cereales, por lo que normalmente no los ve, pero un imán atraerá estas pequeñas limaduras de hierro que están presentes en el cereal, separándolos de los otros componentes del cereal que no son atraídos por el imán (hay más información sobre el magnetismo en los enlaces de referencia a continuación). Triturar el cereal y mezclarlo con agua hace que sea mucho más fácil separar el hierro. Por cierto, esta es también la razón por la que debe usar un palito de paleta de madera o una cuchara de plástico para revolver en el Paso 8 del procedimiento anterior (si su taza no tiene tapa). La mayoría de las cucharas de metal están hechas de acero, que contiene mucho hierro y, por lo tanto, también se sentirán atraídas por su imán (aunque algunos tipos de acero en realidad no son muy magnéticos). La separación del hierro del cereal requiere un campo magnético potente, por lo que necesitamos utilizar un imán de neodimio potente, que en realidad está hecho de los elementos neodimio, hierro y boro (Nd2Fe14B). El neodimio rara vez se encuentra en la naturaleza, por lo que estos imanes a veces se denominan imanes de tierras raras. Los imanes de neodimio generalmente se recubren con una capa delgada de otro metal como el níquel para que parezcan de metal, pero en realidad son un tipo de cerámica. Los materiales cerámicos son similares al vidrio, por lo que estos imanes son frágiles y pueden romperse o romperse con bastante facilidad, a menudo produciendo bordes afilados, si permite que se golpeen entre sí. Debido a esto, así como a su fuerza, deben manejarse con mucho cuidado. Algunos cereales para el desayuno contienen mucho más hierro que otros cereales. Puede averiguar cuánto hierro contiene cualquier cereal leyendo las etiquetas de "Información nutricional" al costado de la caja (como la foto de arriba). Por ejemplo, el cereal "Total" contiene el 100% de la cantidad diaria recomendada de hierro, mientras que el "Trigo desmenuzado" contiene solo el 8%; es por eso que debería ver más limaduras de hierro del cereal Total. Pruebe varios cereales diferentes, ¿la cantidad de hierro que ve coincide con la información de las etiquetas? ¿Es importante que use la misma cantidad de cada cereal y lo agite durante el mismo tiempo? ¿Es importante utilizar la misma cantidad de agua? ¿Por qué o por qué no?
variaciones y actividades relacionada
Próximamente
REFERENCIAS Y ENLACES A MÁS INFORMACIÓN
Otras variaciones de este experimento:
Por qué el hierro es tan importante para tu cuerpo:
Qué cereales para el desayuno tienen más hierro:
Hierro y magnetismo (ferromagnetismo):
Líneas de campo magnético: El efecto Cheerios (y cómo afecta a los insectos que caminan sobre el agua):
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Have you ever wondered what makes a flour dough rise, or why there are lots of little holes inside your bread or pancakes? And what is the difference between baking soda and baking powder? Well, you're in luck because that's what this experiment is all about.
Este experimento está disponible en español Click and expand the tabs below to get started.
what you'll need
experimental procedure
what's happening
Baking soda is the common name for sodium bicarbonate, a type of substance or chemical called a base. When it is mixed with water is simply dissolves with no reaction. Baking powder, however, contains not only sodium bicarbonate but also another type of chemical called an acid (or sometimes two different acids). When these chemicals dissolve in water the base sodium bicarbonate reacts with the acid. This is called a chemical reaction because it results in the creation of one of more new and completely different substances. Acids and bases often react with each other. In this reaction the new substance is a gas called carbon dioxide, which is the tiny bubbles that you observe. You can also hear them popping as the gas escapes.
The baking soda did not react because there was no acid present, but if you add a little acid like vinegar or lemon juice then you will get a reaction that also produces carbon dioxide gas- in fact, lots of gas bubbles and foam! You may have done this reaction before to make the famous vinegar and baking soda volcano! Chemical reactions like this are used in baking breads, pancakes, cookies and other foods. When mixed with flour and water to make a dough the gas bubbles are trapped inside and cause the dough to inflate like a balloon or rise. That's what happened in the third cup when you added flour. This is called leavening, and ingredients like baking powder or baking soda are call leavening agents. Baking this dough at high temperature in an oven causes the flour molecules to lock together into a firm solid structure giving us something good to eat! Meanwhile the carbon dioxide bubbles eventually pop and the gas escapes, leaving behind the tiny little holes we see in baked goods.
variations and related activities
Some recipes use baking soda instead of baking powder because there is some other ingredient already present that provides the acid needed to produce the gas. Some recipes even use both baking soda and baking powder to produce carbon dioxide at different times during the baking.
Most baking powder used today is "Double Acting Baking Powder". It contains two different acids, one which reacts as soon as the water is added and a second acid that doesn't react until it reaches a certain high temperature. This causes the dough to rise twice- once when it is first mixed then again during baking in the oven. You can continue this activity in a tasty way with a simple homemade pancake recipe (see link below), and make it into a real experiment by making some pancakes without the baking powder and baking soda. How do these pancakes compare to the normal ones? What if you leave out one of the other ingredients? Pizza dough and some other baked goods use a very different ingredient- yeast- to make the dough rise. Yeasts are actually tiny living organisms called fungi that "eat" sugars and "burp" carbon dioxide gas. Check out the references below if you would like to experiment with yeast.
references and links to more information
What purpose do the various ingredients serve in baking?:
Try a pancake science recipe and experiment: Other baking science experiments: More baking Soda experiments:
Yeast science and baking experiments:
Hornear con gas (en español)
¿Alguna vez te has preguntado qué hace que la masa de harina se eleve o por qué hay muchos pequeños agujeros dentro de tu pan o panqueques? ¿Y cuál es la diferencia entre bicarbonato de sodio y levadura en polvo? Bueno, estás de suerte porque de eso se trata este experimento.
Lo que necesitarás
Procedimiento experimental
Qué esta pasando
Bicarbonato de sodio es el nombre común del bicarbonato de sodio, un tipo de sustancia o químico llamado base. Cuando se mezcla con agua, simplemente se disuelve sin reacción. Sin embargo, el polvo de hornear contiene no solo bicarbonato de sodio, sino también otro tipo de químico llamado ácido (oa veces dos ácidos diferentes). Cuando estos productos químicos se disuelven en agua, el bicarbonato de sodio básico reacciona con el ácido. Esto se llama reacción química porque da como resultado la creación de una o más sustancias nuevas y completamente diferentes. Los ácidos y las bases a menudo reaccionan entre sí. En esta reacción, la nueva sustancia es un gas llamado dióxido de carbono, que son las diminutas burbujas que observas. También puede escucharlos estallar cuando el gas se escapa.
El bicarbonato de sodio no reaccionó porque no había ácido presente, pero si agrega un poco de ácido como vinagre o jugo de limón, obtendrá una reacción que también produce dióxido de carbono, de hecho, ¡muchas burbujas de gas y espuma! ¡Es posible que hayas hecho esta reacción antes para hacer el famoso volcán de vinagre y bicarbonato de sodio! Las reacciones químicas como esta se utilizan para hornear panes, panqueques, galletas y otros alimentos. Cuando se mezcla con harina y agua para hacer una masa, las burbujas de gas quedan atrapadas en el interior y hacen que la masa se infle como un globo o se eleve. Eso es lo que sucedió en la tercera taza cuando agregaste harina. ¡Hornear esta masa a alta temperatura en un horno hace que las moléculas de harina se bloqueen en una estructura sólida y firme que nos da algo bueno para comer! Mientras tanto, las burbujas de dióxido de carbono eventualmente explotan y el gas escapa, dejando atrás los pequeños agujeros que vemos en los productos horneados.
Variaciones y actividades relacionadas
Algunas recetas usan bicarbonato de sodio en lugar de polvo de hornear porque ya hay algún otro ingrediente presente que proporciona el ácido necesario para producir el gas. Algunas recetas incluso usan bicarbonato de sodio y polvo de hornear para producir dióxido de carbono en diferentes momentos durante la cocción.
La mayor parte del polvo de hornear que se usa hoy en día es el "polvo de hornear de doble acción". Contiene dos ácidos diferentes, uno que reacciona tan pronto como se agrega el agua y un segundo ácido que no reacciona hasta que alcanza una cierta temperatura alta. Esto hace que la masa suba dos veces, una cuando se mezcla por primera vez y luego nuevamente durante la cocción en el horno. Puede continuar este experimento de una manera sabrosa con una receta de panqueques casera simple (link abajo). La masa de pizza y algunos otros productos horneados utilizan un ingrediente muy diferente, la levadura, para hacer que la masa suba. Las levaduras son en realidad pequeños organismos vivos llamados hongos que "comen" azúcares y "eructan" gas de dióxido de carbono. Consulte las referencias a continuación si desea experimentar con levadura
what you'll need
experimental procedure
what's happening
Let’s take a closer look at our crackers. Do they look poofy at all to you? Or are they pretty flat? They should be flat, because we didn’t add any leavening to them. Leavening is the cooking term for any ingredient that will make things that you bake poofy. Things like baking powder and baking soda make bread and cakes rise because they react with other ingredients in the dough to make carbon dioxide bubbles. The holes that we see when we look at a piece of bread are the outsides of those carbon dioxide bubbles. The carbon dioxide escapes into the air, and we have a delicious piece of bread. However, in this case, we didn’t want the crackers to be poofy, so we didn’t put anything in that would make the bubbles. So, our crackers should be flat and delicious! variations and related activities
Coming soon. references and links to more information
Coming soon.
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 You won't believe how easy it is to make your own butter simply by shaking a cup of heavy whipping cream, which comes from milk. Give it a try- and you even get to eat this experiment when you're done! Click tabs below to get started what you'll need
For whipped cream (optional):
Be sure to ask your mom, dad or another adult to help-you can share your butter with them. experimental procedure
Once you finish rinsing your butter, remove all the water and taste it on some bread or a cracker. Most butter you find in the grocery store has salt added, but your butter is unsalted (sometimes called sweet butter). If you don't like the taste, add a pinch of salt. Additional Optional Experimental Procedure: You can also make your own real whipped cream.
what's happening
Butter is very interesting scientifically. We used cream to make butter, but where does cream come from? Cream comes from cows. It is part of the milk that a cow gives. It has a lot of fat in it. Fat occurs in pieces called molecules. These molecules like to stick together in big clumps, but at the dairy they homogenized the milk to keep the fat and everything else all mixed up well. When you shake the cream, however, the molecules which were floating around start sticking to each other. When enough of them stick together they won't float or stay mixed up any more and you have butter!
more detailed explanation
You've probably heard that oil and water don't mix, but milk is in fact a mixture of many different components, including sugars, proteins, fats and yes, water. [Fats and oils are basically similar molecules, also often called lipids, and made of smaller building blocks called fatty acids. Although fat, oil and lipid are often used to refer to fats, "oil" generally refers to a fat that is liquid at normal room temperature and "fat" is solid at room temperature.] The oil or fat in milk can mix with water without separating because they form into little globules sort of like water balloons. The fat is inside a thin skin or membrane which helps attract water somewhat, and because fat is less dense than water, the globules float and form what's called a colloidal suspension or emulsion. The smaller the globules, the easier it is for them to remain emulsified, but if they are too large they will separate and float to the surface. Years ago before milk was homogenized, the fat globules would float to the top and form a layer called the cream, which contained most of the milk's fat. Homogenization breaks up the larger globules into smaller ones, which, along with the milk proteins that then help form a stronger globule membrane, prevent this separation. The cream you buy at the grocery store is separated at the dairy and then homogenized to keep the fat suspended in the liquid. Heavy whipping cream means that it has a very high fat content, 36-40% (normal cream is about 30% fat, while Half & Half is 12% and whole milk 3.5% fat). Butter is essentially pure milk fat.
In our heavy cream, the fat globules are still emulsified, or suspended in the water along with some protein and sugar. If we shake the cream though, the globules will begin to crash into one another and pop or burst their membranes. When this happens the fat molecules spill out and clump together with other fat molecules. At first as this happens the fat traps a lot of air and forms bubbles or foam, which is the whipped cream. The more you shake it, however, the more bubbles pop and the more densely the fat clumps become until they can no longer remain suspended in the water, and they separate completely. This is the butter, and the remaining liquid, mostly water and proteins, is called buttermilk. The butter you make is not only good to eat, but will stay fresh for a long time, especially if it is thoroughly rinsed of all the milk liquid, since the milk can spoil. Adding sugar to the whipped cream not only sweetens and thickens it, but helps prevent the fat bubbles from popping so that it will stay a light fluffy foam much longer. variations and related activities
Try using cold heavy whipping cream to make butter. Try warm cream. Does it take more or less shaking to get to butter? How do you think temperature affects this process? If you like these milk science activities, you can also try our Milk Fireworks experiment, as well as making cottage cheese and glue (see link below) from milk. references and links to more information
Others versions of this activity:
Experiment with the temperature of the cream: Learn more about milk chemistry: What is homogenized milk?: Whipped cream as a science fair project:
What happens when whipped cream comes out of a can?: You can also make glue from milk:
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Click and expand the tabs below to get started. What you'll need
experimental procedure
what's happening
Modern disposable baby diapers contain a small amount (4-5 grams) of polyacrylic acid in a powder form (sodium polyacrylate), which is mixed into the fluff in the middle layer of the diaper. The inside layer of the diaper allows water to pass through it into the absorbent middle layer, and the outer layer is waterproof, so both baby and mommy stay dry. Polyacrylic acid can absorb about more than 100 times its own weight in water, which is why an average sized diaper can absorb up to 16 ounces of water. Luckily that's more than a baby usually pees.
Why is this powder so good at absorbing water? Polyacrylic acid is a polymer made from the monomer acrylic acid. Polymer molecules are kind of like long chain made up of lots of identical links (the monomers). Polyacrylic acid chains contain thousands of monomer units, as well as cross-linking between different molecule chains, which makes them kind of tangle together. Most polymers, such as polyethylene and polystyrene (used in trash bags, plastic bottles, and Styrofoam®, for example) are hydrophobic, meaning they repel water. Polyacrylic acid, however, is very hydrophilic - it attracts water- because of the carboxylic acid groups (COOH) in the polymer, which can hydrogen-bond to water molecules. The cross-linking also helps trap lots of bonded water molecules inside the tangled chains.
Variations and related activities
You can make this activity more colorful by adding a few drops of food coloring to the water. Also try adding some table salt to the water. What happens? [Table salt is sodium chloride (NaCl) and the chloride ions will bond with the SAP and prevent water molecules from doing so.] If you place the wet polymer on a towel or napkin and allow it to dry out for a few days it will dehydrate and shrink back to almost its original powder form and can be used over an over again. Polyacrylic acid, often just called baby diaper polymer or super absorbent polymer (SAP), comes in many forms and has many other applications. SAP is often used to clean up hazardous waste spills- even more hazardous than what ends up in a baby diaper! Just sprinkle the dry powder on the spilled liquid and then sweep or vacuum it up. You can also find SAP in moisture-control potting soils at a garden store. If you over-water your plants the SAP will absorb the excess water. As the soil dries the SAP dehydrates and the excess water returns to the soil, maintaining just the right amount or moisture for the plant to thrive. You can also buy headbands and neckbands that contain SAP inside, after you wet them the water evaporates slowly and keeps you cool for a long time (see the reference link below to make your own!) You can buy Instant Snow powder from many stores online (see references below). Instant snow is exactly the same material, it's just ground up into a much finer powder. This causes it to form smaller molecular structures and puff up instantly when it absorbs water, giving it the look and feel of real snow. It's often used in movies when they want snow in a scene without the need for cold temperatures- and the wet mess when it melts! Orbeez and other water beads are clear spheres and other fun shapes made from the same polyacrylic acid SAP material, but prepared a little differently to form the shapes you see when they absorb water. Typical Orbeez spheres start as 3 or 4 mm beads, but can grow to more than 1" in diameter as they absorb water. Because they are composed almost entirely of water when fully grown, they are essentially invisible in a bowl of water (as long as both the spheres and the liquid water are clean). Water is water. The index of refraction (a measure of how light bends as it passes through a material) of the liquid water is the same as the water in the sphere, so light rays are not refracted as they pass from the water in the bowl to the water in the beads, and the spheres are therefore almost completely indistinguishable from the rest of the water. They also bounce (but can break if you bounce them too hard) and act as little magnifying glasses. Just as with the baby diaper polymer, you can add food colors to make colored Orbeez, and if you let them dry they will shrink back down to little beads that you can use over and over again. references and links to more information
The science of sodium polyacrylate and SAP's:
Here are some other ways to do this experiment:
This video from Science Beyond at the St. Louis Science Center shows you the secret behind one of our most popular demonstrations: Fun with Instant Snow powder: Orbeez!: Make your own cooling headband or neck bandana with SAP:
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