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Chemical Reaction Equations, How to Balance them?

Chemical reaction illustration. Photo: Unsplash

Reaction equation chemistry displays the chemical changes from reagents or reactants to products or reaction products. This equation contains formula-Chemical formulas reagents and products.

Chemical reaction equations. Photo: Shofura / coil tones

In addition, the chemical reaction rate equation also shows the state of the substances in the reaction. The form of this substance is symbolized by (s) solid or solid substance, (l) liquid or liquid, (aq) aqueous or solution in water, and (g) gas.

Examples of Chemical Reaction Equations

Chemical reaction illustration. Photo: Pixabay

We can find chemical reactions in everyday life. For example, burning charcoal to produce carbon dioxide. The reaction equation can be written as follows:

In the charcoal burning equation, charcoal which is carbon is symbolized by being a solid being burned. This triggers a reaction with oxygen gas and produces carbon dioxide in gaseous form.

Another example is the decomposition of ammonium chloride vapor gas to produce ammonia gas and hydrogen chloride gas. Then, the chemical reaction equation can be written as:

NH4Cl (g) -> NH3 (g) + HCl(g)

Chemical Reaction Equations and Equations

John Dalton, the scientist who invented the atomic theory. Photo: wikimedia.commons

Atomic Theory Dalton stated, the atoms that occur during a chemical reaction will never be lost. However, that only changed the order.

That is, writing this chemical reaction must not remove or add atoms.

The number of atoms in the reaction, either on the left or the right, must be the same, so we need to equalize the chemical reaction equation.

As quoted from the book Chemistry published by Erlangga Publisher, the requirements for writing chemical equations include:

  • Writing the chemical formulas of reagents and reaction products must be correct.

  • The sum of the various atoms before the reaction (left arrow) and after the reaction (right arrow) must be the same.

  • The substances involved in the chemical equation are written in parentheses after the chemical formula.

In balancing a chemical reaction, it is permissible to change the coefficient of the chemical formula. The coefficient here is the number of units in the chemical formula.

In order for you to better understand it, consider the following chemical reaction equation:

Al(s(+ H2SO4)aq) -> Al2 (SO4) 3)aq) + H2(g)

The equation above is still not equal, so we have to balance it.

  • The first way is to balance Al atoms first. The Al atoms before the reaction are one. Then, after the reaction there were two of them. To balance it, we write the coefficient value in front of the Al atom before the reaction.

2Al (s(+ H2SO4)aq) -> Al2 (SO4) 3)aq) + H2(g)

  • Next, we balance the S atom by adding the coefficient in front of H2SO4.

2Al (s(+ 3H2SO4)aq) -> Al2 (SO4) 3)aq) + H2(g)

  • Finally, the unequal atom is the H atom, in front of H2 we add a coefficient that is equal to H2 before the reaction.

2Al (s(+ 3H2SO4)aq) -> Al2 (SO4) 3)aq(+ 3H2)g)

  • Now the equation for the reaction to chemistry is equivalent.

Examples of Chemical Reaction Equations and Answers

After knowing how to balance chemical reactions in a simple way. Let us study balance out more complex chemical reactions.

Illustration of child learning online. Photo: Shuutterstock

Consider an example of a balanced chemical reaction equation below:

Unequal equations:

NH3 (g) + O2 (g) -> NO2 (g) + H2O (g)

  • The first step, we assume that NH3 has a coefficient of 1, and we write the other letters first.

NH3 (g) + aO2 (g) –> bNO2 (g) + cH2O (g)

  • After that, we count the number of each atom before the reaction and after the reaction.

The number of N atoms before reaction 1, after reaction b

The number of H atoms before reaction 3, after reaction 2c

The number of atoms of O before reaction 2a, after reaction 2b + c

  • Now we are looking for the coefficient value which is still in the form of letters by means of mathematical substitution.

  • Plug the coefficient into the chemical reaction equation.

NH3 (g) + 7/4 O2g) -> NO2 (g) + 3/2 H2O (g)

  • Finally we perfect the value of the coefficient so that there is no fraction.

4NH3 (g(+ 7O2)g) -> NO2 (g) + 6H2O (g)

This chemical reaction equation involves changing some substances but not removing or forming new substances.

This is an explanation of the chemical reaction equations and how to balance them. To learn it, you have to keep practicing and follow the steps above.

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