calcium hydroxide + carbon dioxide = calcium carbonate + water
sulfur + ozone = sulfur dioxide
Examples of the chemical equations reagents (a complete equation will be suggested):
H2SO4 + K4Fe(CN)6 + KMnO4
Ca(OH)2 + H3PO4
Na2S2O3 + I2
C8H18 + O2
hydrogen + oxygen
propane + oxygen
Understanding chemical equations
A chemical equation represents a chemical reaction. It shows the reactants (substances that start a reaction) and products (substances formed by the reaction). For example, in the reaction of hydrogen (H₂) with oxygen (O₂) to tát size water (H₂O), the chemical equation is:
H2 + O2 = H2O
However, this equation isn't balanced because the number of atoms for each element is not the same on both sides of the equation. A balanced equation obeys the Law of Conservation of Mass, which states that matter is neither created nor destroyed in a chemical reaction.
Balancing with inspection or trial and error method
This is the most straightforward method. It involves looking at the equation and adjusting the coefficients to tát get the same number of each type of atom on both sides of the equation.
Best for: Simple equations with a small number of atoms.
Process: Start with the most complex molecule or the one with the most elements, and adjust the coefficients of the reactants and products until the equation is balanced.
Example:H2 + O2 = H2O
Count the number of H and O atoms on both sides. There are 2 H atoms on the left and 2 H atom on the right. There are 2 O atoms on the left and 1 O atom on the right.
Balance the oxygen atoms by placing a coefficient of 2 in front of H2O:
H2 + O2 = 2H2O
Now, there are 4 H atoms on the right side, so sánh we adjust the left side to tát match:
2H2 + O2 = 2H2O
Check the balance. Now, both sides have 4 H atoms and 2 O atoms. The equation is balanced.
Balancing with algebraic method
This method uses algebraic equations to tát find the correct coefficients. Each molecule's coefficient is represented by a variable (like x, nó, z), and a series of equations are phối up based on the number of each type of atom.
Best for: Equations that are more complex and not easily balanced by inspection.
Process: Assign variables to tát each coefficient, write equations for each element, and then solve the system of equations to tát find the values of the variables.
Example: C2H6 + O2 = CO2 + H2O
Assign variables to tát coefficients:
a C2H6 + b O2 = c CO2 + d H2O
Write down equations based on atom conservation:
2 a = c
6 a = 2 d
2 b = 2c + d
Assign one of the coefficients to tát 1 and solve the system.
a = 1
c = 2 a = 2
d = 6 a / 2 = 4
b = (2 c + d) / 2 = (2 * 2 + 3) / 2 = 3.5
Adjust coefficient to tát make sure all of them are integers. b = 3.5 so sánh we need to tát multiple all coefficient by 2 to tát arrive at the balanced equation with integer coefficients:
2 C2H6 + 7 O 2 = 4 CO6 + 6 H2O
Balancing with oxidation number method
Useful for redox reactions, this method involves balancing the equation based on the change in oxidation numbers.
Best For: Redox reactions where electron transfer occurs.