Octane (C8H18) is a liquid that combusts with oxygen gas (O2) to form water (H2O) and carbon dioxide (CO2). Write a balanced chemical equation for this reaction and explain the scientific principle (statement) that requires the balancing of an equation to make it conform to reality.
How about
2 C8H18 + 25 O2 ---> 18 H2O + 16 CO2
C 16 left 16 right
H 36 left 36 right
O 50 left 18 + 32 = 50 right
Conservation of mass means there must be the same atoms of each element left and right. In a chemical (not nuclear) reaction one element does not change into another.
The balanced chemical equation for the combustion of octane (C8H18) with oxygen gas (O2) to form water (H2O) and carbon dioxide (CO2) can be written as follows:
C8H18 + 12.5O2 -> 8CO2 + 9H2O
Now let's explain the scientific principle that requires balancing of the equation – the Law of Conservation of Mass. This principle states that in any chemical reaction, mass is neither created nor destroyed; it is conserved. This means that the total mass of the reactants must be equal to the total mass of the products.
When a chemical equation is unbalanced, it suggests an unequal distribution of atoms between the reactants and products. This violates the Law of Conservation of Mass because it would imply that mass is either being created or destroyed. To abide by this fundamental law, we must balance the equation.
In the case of the given reaction, we have 8 carbon atoms on the left side (C8H18) and only 1 carbon atom on the right side (8CO2). Similarly, we have 18 hydrogen atoms on the left side (C8H18) and only 9 hydrogen atoms on the right side (9H2O). Additionally, there are 25 oxygen atoms on the left side (12.5O2) and 25 oxygen atoms on the right side (8CO2 + 9H2O).
To balance the equation, we need to adjust the coefficients (numbers placed in front of the compounds) to ensure the same number of atoms of each element is present on both sides of the equation. By placing a coefficient of 8 in front of CO2 and 9 in front of H2O, we are able to balance the carbon and hydrogen atoms. To balance the oxygen atoms, we need to ensure there are 25 oxygen atoms on both sides. This leads us to use a coefficient of 12.5 in front of O2.
By balancing the chemical equation, we ensure that the number of atoms on both sides is equal, thus satisfying the Law of Conservation of Mass. This balancing process maintains the accurate representation of chemical reactions, enabling scientists to quantify and predict the amount of reactants needed and the amount of products formed.