Cause and Effect

         Chemistry is the science of dealing with the compounds, elements, and molecular structure of matter. Essentially, chemistry is the science of examining substances and objects to find out what they're made of and how the react to different conditions.

        A cause-effect relationship is a relationship in which one event (the cause) makes another event happen (the effect). One cause can have several effects. For example, let's say you were conducting an experiment using regular high school students with no athletic ability. The purpose of our experiment is to see if becoming an all-star athlete would increase their attractiveness and popularity ratings among other high school students.

       Suppose that your results showed that not only did the students view the all-star athletes as more attractive and popular, but the self-confidence of the athletes also improved.The key principle of establishing cause and effect is proving that the effects seen in the experiment happened after the cause.

         Chemical reactions occur when chemical bonds between atoms are formed or broken. The substances that go into a chemical reaction are called the reactants, and the substances produced at the end of the reaction are known as the products. An arrow is drawn between the reactants and products to indicate the direction of the chemical reaction, though a chemical reaction is not always a "one-way street," as we'll explore further in the next section.

For example, the reaction for breakdown of hydrogen peroxide ($\text{H}_{2}$H, start subscript, 2, end subscript$\text{O}_{2}$O, start subscript, 2, end subscript) into water and oxygen can be written as:

$2 \text{H}_{2}$2, H, start subscript, 2, end subscript$\text{O}_{2} \text{(hydrogen peroxide)}$O, start subscript, 2, end subscript, left parenthesis, h, y, d, r, o, g, e, n, space, p, e, r, o, x, i, d, e, right parenthesis $\rightarrow$right arrow $2\text{H}_{2}\text O \text{(water)}$2, H, start subscript, 2, end subscript, O, left parenthesis, w, a, t, e, r, right parenthesis + $\text{O}_{2}\text{(oxygen)}$O, start subscript, 2, end subscript, left parenthesis, o, x, y, g, e, n, right parenthesis

In this example hydrogen peroxide is our reactant, and it gets broken down into water and oxygen, our products. The atoms that started out in hydrogen peroxide molecules are rearranged to form water molecules ($\text{H}_{2}\text O$H, start subscript, 2, end subscript, O) and oxygen molecules ($\text O_2$O, start subscript, 2, end subscript).

You may have noticed extra numbers in the chemical equation above: the $2$2s in front of hydrogen peroxide and water. These numbers are called coefficients, and they tell us how many of each molecule participate in the reaction. They must be included in order to make our equation balanced, meaning that the number of atoms of each element is the same on the two sides of the equation.

Equations must be balanced to reflect the law of conservation of matter, which states that no atoms are created or destroyed over the course of a normal chemical reaction. You can learn more about balancing reactions in the balancing chemical equations tutorial.

The causes of chemical reactions:

1. Occurs due to burning.

2. Occurs due to mixing of substances.

3. Occurs due to the flow of electricity.

The chemical reaction equation is written as follows:

A and B : reactant

C and D : reaction product.

In the reaction equation there is a symbol of the form of substance: s (solid), aq (aqueous), l (liquid) and g (gas).

The effect of chemical reactions

The formation of gas bubbles.

Gases produced in chemical reactions sometimes cause bubbles to form

Formation of Sludge

Color Changes Occurred

Temperature Changes

Lighting

Volume Changes Occurred

Conductivity change

Odor change occurred