If 100 molecules of oxygen react, how many molecules of water will be produced?
Answers
Chemical Reactions
Chemical Equations Equations at the Atomic and Macroscopic Scale Balancing Chemical Equations
Mole Ratios Predicting Mass Produced or Consumed in a Chemical Reaction Limiting Reagents
Because atoms are neither created nor destroyed in a chemical reaction, the total mass of products in a reaction must be the same as the total mass of the reactants.
Chemical Equations
Chemical reactions are described by chemical equations.
Example: The reaction between hydrogen and oxygen to form water is represented by the following equation.
2 H2 + O2-----> 2 H2O
It is often useful to indicate whether the reactants or products are solids, liquids, or gases by writing an s, l, or g in parentheses after the symbol for the reactants or products, as shown in the following equations.
2 H2(g) + O2(g) -----> 2 H2O(g)
2 Al(s) + Fe2O3(s) -----> Al2O3(s) + 2 Fe(l)
Because so many reactions occur when solutions of two substances dissolved in water are mixed, a special symbol, aq, is used to describe these aqueous solutions.
The process in which a sample dissolves in water will be indicated by equations such as the following.
H2O
C12H22O11(s) C12H22O11(aq)
A chemical equation is a statement of what can happen, not necessarily what will happen. The following equation, for example, does not guarantee that hydrogen will react with oxygen to form water.
2 H2(g) + O2(g) -----> 2 H2O(g)
It is possible to fill a balloon with a mixture of hydrogen and oxygen and find that no reaction occurs until you touch the balloon with a flame. The balanced equation for this reaction describes the relationship between the amounts of hydrogen and oxygen consumed and the water formed if or when this reaction is initiated.