Final answer:
The part of the chemical equation before the arrow is called the reactants. It is balanced using stoichiometry, ensuring equal numbers of atoms for each element on both sides, and the coefficients represent moles of the substances involved.
Step-by-step explanation:
In the chemical equation C₂H₆O +3 O₂ → 2CO₂+ 3H₂O, the part of the equation before the arrow ( → ) is called the reactants. The reactants are the substances that undergo a chemical reaction when the equation is balanced. Stoichiometry is the area of chemistry that deals with the quantitative relationships between reactants and products in chemical reactions, often involving calculations based on moles. The coefficients in a balanced chemical equation typically represent the number of moles of each substance.
To balance a chemical equation, one must ensure that the number of atoms of each element is the same on both sides of the equation. This may involve using whole-number coefficients to specify the amounts of reactants and products. For example, balancing the equation for the combustion of ethanol (C₂H₆O) requires adjusting the coefficients to reflect the correct stoichiometric ratios. In this case, the balanced equation is C₂H₆O + 3O₂ → 2CO₂ + 3H₂O, indicating that one mole of ethanol reacts with three moles of oxygen to produce two moles of carbon dioxide and three moles of water.