Lab 8 Balancing Chemical Equations

Steps for balancing a basic chemical equation

1. Write the unbalanced equation for the reaction. Place the reactants on the left side of the arrow and the products on the right side of the arrow. 2. Tally the number of atoms of each element on both sides of the equation. a. If the same number of atoms of each element appears on both sides of the equation, the formula is balanced. No more steps are necessary. b. If the numbers of the atoms are not equal, the coefficients must be adjusted to balance the equation. 3. Starting with atoms that appear in only one substance on each side of the arrow, adjust coefficients for each formula in order to make the number of atoms on both sides equal. 4. Continue adjusting the coefficients until the number of atoms of each element is the same on both sides of the equation.

Element

A pure substance made of only one kind of atom

What can be adjusted to balanced chemical equations?

Coefficients (small numbers), but subscripts cannot be changed; they're intrinsic to the structure of the molecule

Balancing chemical equations is the application of what?

It is the application of the law of conservation of mass, stating mass is neither created or destroyed

What do subscripts represent?

Subscripts represent the number of atoms present for a particular element in a molecule

What are the changes that do occur during a chemical reaction?

The changes that occur during any reaction are simply rearrangements of the atoms

What do balanced equations determine?

They determine the amount of product that can be produced in a chemical reaction and to ensure that the appropriate amounts of reactants are added to allow reactions to occur

Identify the coefficient for carbon dioxide (CO2) in the following balanced equation: C3H8 + 5 H2 → 4 H2O + 3 CO2 a. 3 b. C c. 2 d. 8

a. 3 Numbers, called coefficients, are placed before the symbol for an element or the formula for a compound in a chemical equation.

What do the coefficients in a chemical equation represent?

indicate the number of molecules of a compound, or the number of ATOMS of an element that is not part of a molecule/ compound, presennt in the reaction

Molecule

smallest unit of a compound that retains chemical properties of a compound

Compound

substance that consists of identical molecules composed of two or more elements.

Atom

the smallest unit of an element that maintains the chemical properties of that element