Chemical Formulas and Reactions

Front

What is a chemical formula?

Back

A chemical formula is a way of expressing the composition of a substance using symbols for its constituent elements and numbers to indicate the quantity of each element.

Front

What does a subscript in a chemical formula indicate?

Back

A subscript indicates the number of atoms of the element that are present in a molecule. For example, in H2O, the '2' indicates there are two hydrogen atoms.

Front

What does a coefficient in a chemical equation represent?

Back

A coefficient indicates the number of molecules or moles of a substance involved in a chemical reaction. For example, in 2H2 + O2 -> 2H2O, the '2' before H2O means there are two water molecules produced.

Front

How do you determine the total number of atoms in a chemical formula?

Back

To find the total number of atoms, add the number of atoms of each element together, taking into account the subscripts.

Front

What is a balanced chemical equation?

Back

A balanced chemical equation has the same number of each type of atom on both sides of the equation, indicating that mass is conserved during the reaction.

Front

What is the difference between a reactant and a product in a chemical reaction?

Back

Reactants are the starting substances that undergo a chemical change, while products are the substances formed as a result of the reaction.

Front

What is the significance of the law of conservation of mass in chemical reactions?

Back

The law of conservation of mass states that mass is neither created nor destroyed in a chemical reaction, meaning the total mass of reactants equals the total mass of products.

Front

What does the term 'yield' mean in a chemical equation?

Back

The term 'yield' refers to the amount of product formed in a chemical reaction, often represented by an arrow in the equation.

Front

What is an example of a simple chemical reaction?

Back

An example of a simple chemical reaction is the combustion of methane: CH4 + 2O2 -> CO2 + 2H2O.

Front

What is a diatomic molecule?

Back

A diatomic molecule is a molecule composed of two atoms, which can be of the same or different elements, such as O2 (oxygen) or HCl (hydrogen chloride).