couse and effect chemical reaction

A chemical reaction is a process that leads to the transformation of one set of chemical substances to another.[1] Classically, chemical reactions encompass changes that only involve the positions of electrons in the forming and breaking of chemical bonds between atoms, with no change to the nuclei (no change to the elements present), and can often be described by a chemical equation. Nuclear chemistry is a sub-discipline of chemistry that involves the chemical reactions of unstable and radioactive elements where both electronic and nuclear changes can occur.

The substance (or substances) initially involved in a chemical reaction are called reactants or reagents. Chemical reactions are usually characterized by a chemical change, and they yield one or more products, which usually have properties different from the reactants. Reactions often consist of a sequence of individual sub-steps, the so-called elementary reactions, and the information on the precise course of action is part of the reaction mechanism. Chemical reactions are described with chemical equations, which symbolically present the starting materials, end products, and sometimes intermediate products and reaction conditions.

Chemical reactions happen at a characteristic reaction rate at a given temperature and chemical concentration. Typically, reaction rates increase with increasing temperature because there is more thermal energy available to reach the activation energy necessary for breaking bonds between atoms.

Reactions may proceed in the forward or reverse direction until they go to completion or reach equilibrium. Reactions that proceed in the forward direction to approach equilibrium are often described as spontaneous, requiring no input of free energy to go forward. Non-spontaneous reactions require input of free energy to go forward (examples include charging a battery by applying an external electrical power source, or photosynthesis driven by absorption of electromagnetic radiation in the form of sunlight).

Different chemical reactions are used in combinations during chemical synthesis in order to obtain a desired product. In biochemistry, a consecutive series of chemical reactions (where the product of one reaction is the reactant of the next reaction) form metabolic pathways. These reactions are often catalyzed by protein enzymes. Enzymes increase the rates of biochemical reactions, so that metabolic syntheses and decompositions impossible under ordinary conditions can occur at the temperatures and concentrations present within a cell.

The general concept of a chemical reaction has been extended to reactions between entities smaller than atoms, including nuclear reactions, radioactive decays, and reactions between elementary particles as described by quantum field theory.

Chemical Change
A. Understanding
            Chemical changes are changes in substances that produce new substances. For example: the paper before being burned has properties different from the paper before being burned. Examples of chemical changes are rice rot, stale milk, stale vegetables, rotting eggs, salted eggs, rusted iron, etc.

B. The characteristics of chemical changes
1. The formation of new types of substances
2. Substances that change can not return to their original shape
3. Followed by changes in chemical properties through chemical reactions
During chemical mass changes the substance before the reaction is equal to the mass of the substance after the reaction.

C. The causes of chemical changes

1. Can occur due to combustion
2. Can occur due to mixing of substances
3. Can occur due to the flow of electricity
4. Can occur due to mixing of two or more substances that produce new substances. Example:
1) Sodium hydroxide + hydrochloric acid
2) When recharging the battery

An example: Whether you call her “Kiki” from her character’s name in “Fresh Beat Band” or her real name of Yvette Gozalez-Nacer, she is still pretty hot.

In this tutorial, you’ll learn about what are generally considered the six types of chemical reaction.  Though not particularly interesting, this will come in very handy when you start learning about how to predict reaction products.

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Reaction type 1:  Combustion reaction

A combustion reaction occurs when stuff burns.  OK… I assume you already knew that, so I’ll just give you the chemical definition:

Combustion reactions take place when a compound containing carbon and hydrogen reacts with oxygen to make water vapor, carbon dioxide, and heat.

This sounds annoying, I know, but it’s really not.  Consider the general form of a combustion reaction:

CₘHₙ + O₂ → CO₂ + H₂O

Basically, if anything containing C and H reacts with oxygen gas, you end up with carbon dioxide and water vapor.  And lots of heat.

British Petroleum (BP) was kind enough to spill a vast quantity of oil in the ocean in 2010, some of which was burned. Thanks BP!

One example of combustion takes place when cyclohexane (which is present in crude oil) is burned:

C₆H₁₂ + 9 O₂ → 6 CO₂ + 6 H₂O

These birds like being covered in crude oil so much that many die from sheer joy. Thanks BP!

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Reaction type 2:  Synthesis reaction

A synthesis reaction is a reaction in which simple compounds are combined to make a more complex one.  An analogue you might see in everyday life if that of making a turkey sandwich – you start with two slices of bread and a slice of turkey and end up with a sandwich.  The general form for a synthesis reaction reflects this:

A + B →C

One specific example of this sort of reaction occurs when sodium and chlorine gas combine to make sodium chloride:

2 Na + Cl₂ →2 NaCl

For the reactions you’ll run into, it’s likely that the reagents will be fairly simple and the products will be easy to predict.  Keep in mind, however, that the real world doesn’t work that way.

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Reaction type 3:  Decomposition reaction

A decomposition reaction is one where a molecule breaks apart into simpler ones.  For example, I would guess that Johannes Sebastian Bach is in much simpler pieces now than when he was buried in 1750.

I know… you were expecting me to tell that old joke. Nope. Not gonna do it. I’ll just make fun of his sheep-like hair instead.

In the chemical world, the general form for a decomposition reaction is this:

C → A + B

And an example of it occurs when hydrogen peroxide breaks apart to form oxygen gas and water:

2 H₂O₂  → 2 H₂O + O₂

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Reaction Type 4:  Single displacement reaction

Also known as a “single replacement reaction”, this type of reaction occurs when a pure element switches places with an element in a chemical compound.  Essentially, two atoms switch places, where one of the atoms isn’t stuck to anything else.  The general form of this reaction is:

A + BC → B + AC

In this case, the elements A and B switched places.  This type of a reaction is also a very common type of redox reaction, which you’ll learn about when you’ve done some more chemistry.

Many metals will boil when you place them into a strong acid.  For example, if you put magnesium into hydrochloric acid, you’ll get the following single-displacement reaction:

Mg + 2 HCl → H₂ + MgCl₂

Because hydrogen is a gas, bubbles can be seen during this reaction.

All of which makes “hot tub night” more adventurous than usual.

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Reaction type 5:  Double displacement reaction

Also called a double “replacement” reaction, this type of reaction occurs when the cations of two chemical compounds switch places.  The general form for this reaction is:

AB + CD → CB + AD

In which you can see that A and C switched places.  If you were, for some reason, interested in adding hydrochloric acid to silver nitrate, you’d see the following double displacement reaction:

HCl + AgNO₂ → AgCl + HNO₂

Silver chloride will eventually degrade in light to form silver metal and chloride gas, so if you’re willing to wait around, you’ll eventually be able to have a very small amount of impure silver and a very small amount of unbelievably toxic gas to play with.  Which, now that I mention it, seems like a very bad idea.

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Reaction type 6:  Acid-base reaction

If you combine an acid with a base, you’ll get water and something else.  Well, this isn’t entirely true, depending on your definition of an acid and base, but for most practical purposes, we can assume that this works out pretty well.  In any case, acid-base reactions are pretty much the same thing as double displacement reactions, except that water is one of the things that’s made:

HA + BOH →BA + H₂O

As you can see, the H and B switched places, which is where the water came from.  Aside from that, it’s the same thing as a double displacement reaction.

One example of an acid-base reaction occurs when nitric acid is neutralized with sodium hydroxide:

HNO₃ + NaOH → NaNO₃ + H₂O

Incidentally, I would recommend that if you do this particular reaction you be very careful, as both nitric acid and sodium hydroxide are very caustic.