Why Does Ice Float?

There are two parts to the answer for this question. First, let's take a look at why anything floats. Then, let's examine why ice floats on top of liquid water, instead of sinking to the bottom.

A substance floats if it is less dense, or has less mass per unit volume, than other components in a mixture. For example, if you toss a handful of rocks into a bucket of water, the rocks, which are dense compared to the water, will sink. The water, which is less dense than the rocks, will float. Basically, the rocks push the water out of the way, or displace it. For an object to be able to float, it has to displace a weight of fluid equal to its own weight.

Water reaches its maximum density at 4°C (40°F). As it cools further and freezes into ice, it actually becomes less dense. On the other hand, most substances are most dense in their solid (frozen) state than in their liquid state. Water is different because of hydrogen bonding.

A water molecule is made from one oxygen atom and two hydrogen atoms, strongly joined to each other with covalent bond. Water molecules are also attracted to each other by weaker chemical bonds (hydrogen bonds) between the positively-charged hydrogen atoms and the negatively-charged oxygen atoms of neighboring water molecules. As water cools below 4°C, the hydrogen bonds adjust to hold the negatively charged oxygen atoms apart. This produces a crystal lattice, which is commonly known as 'ice'.

Ice floats because it is about 9% less dense than liquid water. In other words, ice takes up about 9% more space than water, so a liter of ice weighs less than liter water. The heavier water displaces the lighter ice, so ice floats to the top. One consequence of this is that lakes and rivers freeze from top to bottom, allowing fish to survive even when the surface of a lake has frozen over. If ice sank, the water would be displaced to the top and exposed to the colder temperature, forcing rivers and lakes to fill with ice and freeze solid.

What Is In Chewing Gum?

Originally, chewing gum was made from the latex sap of the sapodilla tree (native to Central America). This sap was called chicle. Other natural gum bases may be used, such as sorva and jelutong. Sometimes beeswax or paraffin wax is used as a gum base. After World War II, chemists learned to make synthetic rubber, which came to replace most natural rubber in chewing gum (e.g., polyethylene and polyvinyl acetate). The last U.S. manufacturer to use chicle is Glee Gum.

In addition to the gum base, chewing gum contains sweeteners, flavorings, and softeners. Softeners are ingredients such as glycerin or vegetable oil that are used to blend the other ingredients and help prevent the gum from becoming hard or stiff.

Neither natural nor synthetic latex are readily degraded by the digestive system. However, if you swallow your gum it will almost certainly be excreted, usually in pretty much the same condition as when you swallowed it. However, frequent gum swallowing may contribute to the formation of a bezoar or enterolith, which is a sort of intestinal stone.

How Does Fireworks Work???

Firecrackers, sparklers, and aerial shells are all examples of fireworks. Though they share some common characteristics, each type works a little differently.

Firecrackers

Firecrackers are the original fireworks. In their simplest form, firecrackers consists of gunpowder wrapped in paper, with a fuse. Gunpowder consists of 75% potassium nitrate (KNO₃), 15% charcoal (carbon) or sugar, and 10% sulfur. The materials will react with each other when enough heat is applied. Lighting the fuse supplies the heat to light a firecracker. The charcoal or sugar is the fuel. Potassium nitrate is the oxidizer, and sulfur moderates the reaction. Carbon (from the charcoal or sugar) plus oxygen (from the air and the potassium nitrate) forms carbon dioxide and energy. Potassium nitrate, sulfur, and carbon react to form nitrogen and carbon dioxide gases and potassium sulfide. The pressure from the expanding nitrogen and carbon dioxide explode the paper wrapper of a firecracker. The loud bang is the pop of the wrapper being blown apart.

Sparklers

A sparkler consists of a chemical mixture that is molded onto a rigid stick or wire. These chemicals often are mixed with water to form a slurry that can be coated on a wire (by dipping) or poured into a tube. Once the mixture dries, you have a sparkler. Aluminum, iron, steel, zinc or magnesium dust or flakes may be used to create the bright, shimmering sparks. An example of a simple sparkler recipe consists of potassium perchlorate and dextrin, mixed with water to coat a stick, then dipped in aluminum flakes. The metal flakes heat up until they are incandescent and shine brightly or, at a high enough temperature, actually burn. A variety of chemicals can be added to create colors. The fuel and oxidizer are proportioned, along with the other chemicals, so that the sparkler burns slowly rather than exploding like a firecracker. Once one end of the sparkler is ignited, it burns progressively to the other end. In theory, the end of the stick or wire is suitable to support it while burning.

Rockets & Aerial Shells

When most people think of 'fireworks' an aerial shell probably comes to mind. These are the fireworks that are shot into the sky to explode. Some modern fireworks are launched using compressed air as a propellent and exploded using an electronic timer, but most aerial shells remain launched and exploded using gunpowder. Gunpowder-based aerial shells essentially function like two-stage rockets. The first stage of an aerial shell is a tube containing gunpowder, that is lit with a fuse much like a large firecracker. The difference is that the gunpowder is used to propel the firework into the air rather than explode the tube. There is a hole at the bottom of the firework so the expanding nitrogen and carbon dioxide gases launch the firework into the sky. The second stage of the aerial shell is a package of gunpowder, more oxidizer, and colorants. The packing of the components determines the shape of the firework.

Who Has Never Cries When Cutting Onions??

Why do onions make you cry?

It is not the strong odor of the onion that makes us cry, but the gas that the onion releases when we sever this member of the lily family.

Onions are known for their ability to reduce cooks to tears, and for the remarkable way in which their aroma is transformed during frying. Sulphur chemicals are responsible in both cases. The onion itself contains oil, which contains sulfur, an irritant to both our noses and to our eyes. Cutting an onion arouses a gas contained within the onion, propanethiol S-oxide, which then couples with the enzymes in the onion to emit a passive sulfur compound. When this upwardly mobile gas encounters the water produced by the tear ducts in our eyelids, it produces sulfuric acid.

These sulfured compounds react with the moisture in your eyes forming sulfuric acid, which produces a burning sensation. The nerve endings in your eyes are very sensitive and so they pick up on this irritation.

An automatic reaction many people show is to rub their eyes with their hands, which often makes the situation worse, because our hands are covered with the sulfur compounds from cutting the onion, which we then rub directly into our eyes.

Tricks to make onion-dicing less problematic:

The only remedy for this problem is to boil the onion, not to slice it or cut it up, which is not very practical. Some people suggest putting the onion in the fridge or the freezer for a few minutes because the cold decreases the speed of the chemical reaction. Another tip is to slice the area around the root of the onion last. Why? Because there are more sulfur compounds in the onion root.

Sulfuric acid irritates the eyes. In response to this acid, our eyes automatically blink, and produce tears which wash the eye and flush out the acid.

Why Meals Cook Faster In Pressure Cooker??

Pressure cookers are designed to cook foods at higher temperatures so the cooking gets done faster.

A pressure cooker consists of a pot and lid, which are usually made of metals such as aluminum or stainless steel. The lid has a rubber ring to seal off the space between the lid and the pot, a safety valve made of low melting point alloy, a vent to allow steam to escape, and a detachable vent stopper or pressure regulator that sits on top of the vent throughout the cooking process. This pressure regulator generates extra force (pressure) in addition to the atmospheric pressure (1 atm), which allows water inside the pot to boil under a higher pressure and hence at a temperature higher than its normal boiling point (100°C). So, food can be cooked at a higher temperature (usually 125°C for most pressure cookers). Generally, for every 10°C increase, chemical reaction rate doubles.

Besides cooking faster, this method retains more nutrients present in the food than other methods. And did you know that a pressure cooker is often used by mountain climbers? Without it, water boils off before reaching 100ºC because of the lower atmospheric pressure at high altitudes, leaving the food improperly cooked.

All right. As you know, water normally boils at 100°C, so the temperature of water can’t exceed 100°C in an open vessel (like what’s used in conventional cooking). Under normal conditions (1 atmosphere external pressure at sea level), any food in water can’t be cooked at temperatures greater than 100°C. However, the boiling point of water varies with external pressures—water boils at a higher temperature when the external pressure is increased. So the higher pressure inside a pressure cooker lets the water boil at temperatures greater than 100°C. Make sense? When the external pressure is lowered, water boils at a lower temperature.

The advantages of using a pressure cooker besides saving time:

Use less fuel, and there’s better retention of certain nutrients due to less water required and shortened cooking time (up to 70% faster than with conventional cookers). In addition, toxins and microbes can be destroyed more efficiently at greater temperatures. The same logic applies to canning foods and autoclave instruments

Eat YouR Appl3 QuickLY!!!

Have you ever realize that after you cut an apple, it turns brown in a few minutes??





Apples discolor or turned brown when peeled or bruised and exposed to air.

There are millions of tiny cells inside each apple. When cutting the apple, it cells get exposed to air. This damages the wall that protects each cell and exposes its contents to oxygen in the air.


This discoloration or browning is due to oxygen, O2, reacting with chemicals released, breaking down the cells in the fruit. The reaction is called enzymatic oxidation as it is a process catalyzed by the enzymes present in the apples. However, the enzymes are destroyed by certain chemicals (e.g. Vitamin C - Absorbic acid) or by high heat. Vitamin C, being an highly reactive anti-oxidant reacts with the O2 in the air, preventing or slowing down the enzymatic oxidation of the apples.