In burning, the two atoms or molecules will combine and release energy. Usually one of the two molecules is oxygen or something else chemically like it called an oxidizer. When the molecules combine and release energy, it is released in the form of heat and often light. Hydrogen burns with oxygen and produces water.

Fire is the result of applying enough heat to a fuel source, when you’ve got a whole lot of oxygen around. As the atoms in the fuel heat up, they begin to vibrate until they break free of the bonds holding them together and are released as volatile gases. These gases react with oxygen in the surrounding atmosphere.

During a home fire, there’s an increased level of carbon monoxide and carbon dioxide as well as damaging levels of chemical and thermal irritants. These irritants can permanently damage a person’s or animal’s respiratory system and cause death.

Chemical reactions that complete in a very short time, such as less than 10 -6 seconds, they are called fast reactions. Examples: Magnesium ribbon is burnt in the flame of Bunsen burner; it quickly gets combusted with a noticeable spark. Similarly, a neutralization reaction between acids and bases is a fast reaction.

Reactions in phases that easily mix, such as gases and liquids, occur much faster than reactions between solids. The extent of mixing of the reactants influences the frequency of molecular collisions – if reactants are more thoroughly mixed, the molecules will collide more often and thus react faster.

Fast reactions: These reactions are so fast that they occur as soon as the reactants are bought together. Generally, these reactions involve ionic species and thus, are known as ionic reactions. These reactions take about 10−14 to 10−16 seconds for completion.

Seven top tips to improve your reflexes

1. Pick a sport, any sport – and practise. What exactly do you want to improve your reflexes for?
2. Chill out.
3. Eat a lot of spinach and eggs.
4. Play more video games (no, really)
5. Use your loose change.
6. Playing ball.
7. Make sure you get enough sleep.

The pressure of gaseous reactants has basically the same effect as concentration. The higher the reactant pressure, the faster the reaction rate. This is due to the increased number of collisions. But if there’s a complex mechanism involved, changing the pressure may not have the expected result.

Reaction Rates

• The concentration of the reactants. The more concentrated the faster the rate.
• Temperature. Usually reactions speed up with increasing temperature.
• Physical state of reactants.
• The presence (and concentration/physical form) of a catalyst (or inhibitor).
• Light.

1. Increase concentration. This increases the number of collisions. The more collisions per second, the faster the reaction.
2. Increase temperature. This increases the number of collisions because the molecules are moving faster.
3. Use a catalyst. A catalyst lowers the barrier to the reaction.

To slow down a reaction, you need to do the opposite. Factors that can affect rates of reactions include surface area, temperature, concentration, and the presence of catalysts and inhibitors. Concentration – another way to increase the rate of a chemical reaction is to increase the concentration of the reactants.

Some signs of a chemical change are a change in color and the formation of bubbles. The five conditions of chemical change: color change, formation of a precipitate, formation of a gas, odor change, temperature change.

A chemical change occurs whenever matter changes into an entirely different substance with different chemical properties. Because chemical changes result in different substances, they often cannot be undone.

A change in color is also another characteristic of a chemical reaction taking place. This change in color is evidence of a chemical reaction. However, one must be careful; sometimes a change in color is simply the mixing of two colors, but no real change in the composition of the substances in question.

The color of an object depends upon which wavelengths of light it reflects back to your eyes. That means changes in temperature cause the liquid crystals to change shape, thereby reflecting different colors of light and causing the color of the “stone” to change.

When two or more substances combine, they create one or more new substances, which sometimes have different molecular structures from the original substances, meaning they absorb and radiate light in different ways, leading to a color change.