# Write a chemical equation and label the reactants and products

### Write a chemical equation and label the reactants and products

Also, the convention is to use all whole numbers when balancing chemical equations. With these equations, an arrow is used to indicate that a chemical reaction has taken place. We have six hydrogen atoms in the reactants, so we need six hydrogen atoms in the products. The Law of conservation of mass says that "Atoms are neither created, nor distroyed, during any chemical reaction. Chapter 4 Chemical Reactions and Equations Opening Essay The space shuttle—and any other rocket-based system—uses chemical reactions to propel itself into space and maneuver itself when it gets into orbit. Example 1 Write and balance the chemical equation for each given chemical reaction. But if we count the number of oxygen atoms in the reactants and products, we find that there are two oxygen atoms in the reactants but only one oxygen atom in the products. They indicate the number of each chemical species that reacts or is formed. Thus, we have accomplished step 1 above. The law of conservation of matter says that matter cannot be created or destroyed. To proceed, the equation must first be balanced.

Before being accepted, a law must be verified many times under many conditions. A balanced chemical equation has the same number and types of atoms on both sides of the arrow.

This is a good example of an exothermic reaction, a reaction in which heat is given off. For example, consider the reaction of ethane C2H6 with oxygen to yield H2O and CO2, represented by the unbalanced equation: Following the usual inspection approach, one might first balance C and H atoms by changing the coefficients for the two product species, as shown: This results in seven O atoms on the product side of the equation, an odd number—no integer coefficient can be used with the O2 reactant to yield an odd number, so a fractional coefficient,is used instead to yield a provisional balanced equation: A conventional balanced equation with integer-only coefficients is derived by multiplying each coefficient by 2: Finally with regard to balanced equations, recall that convention dictates use of the smallest whole-number coefficients.

The head of the arrow typically points toward the right or the product side of the equation, although some equations may indicate equilibrium with the reaction proceeding in both directions simultaneously. Thus it is easier to balance PO4 as a unit rather than counting individual phosphorus and oxygen atoms. Instead, the chemist must identify the reactants and products and then write them in the form of a chemical equation that may or may not be balanced as first written.

The following is an efficient approach to balancing a chemical equation using this method. Yeasts are single-celled fungi. The chemical equation that represents this reaction is written like this: You can read the equation like this: One molecule of methane gas reacts with two molecules of oxygen gas to form one molecule of carbon dioxide gas and two molecules of water vapor.

Stoichiometry: Chemical Formulas and Equations Chemical equations What happens to matter when it undergoes chemical changes? Changing a subscript changes the actual identity of a product or reactant.

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