Study Guide

# Stoichiometry Terms

## Stoichiometry Terms

### Actual Yield

When a chemical reaction is completed, this is the amount of product that you actually make (the amount of stuff you can weigh).

### Atomic Mass

The mass of an atom expressed in atomic mass units (amu).

A number equal to 6.023 × 1023. It is also equal to the number of atoms or molecules in one mole of a substance.

### Chemical Equation

A chemical equation is a representation of a chemical reaction where the reactants are given on the left hand side of an arrow followed by the products of a reaction on the right hand side.

### Chemical Reaction

In a chemical reaction, a chemical change must occur; the hallmark of any chemical reaction is the creation of a new substance. Physical changes can also occur during a chemical reaction.

### Isotope

Variant of a chemical element that has the same number of protons, but different numbers of neutrons.

### Law of Conservation of Mass

A scientific principle that states that matter cannot be created nor destroyed.

### Limiting Reagent

The limiting reagent is the chemical in a reaction that determines how far a reaction can proceed or how much product a reaction can make.

### Macroscopic

Visible to the naked, or unaided, eye.

### Microscopic

Extremely small; visible with a microscope.

### Molar Mass

The mass in one mole of a substance.

### Mole

A measurement of an amount of a substance, always equal to 6.023 × 1023 units.

### Molecule

A group of atoms that are held together by covalent bonds.

### Percent Composition

The percentage by mass of each element in a compound.

### Percent Yield

The actual yield of a chemical reaction divided by the theoretical yield times 100%.

### Physical State

The state of the matter: solid, liquid, or gas.

### Product

A molecule that is produced in a chemical reaction. Products are generated by reactants.

### Reactant

The chemicals that are present before a chemical reaction takes place. They react together to produce new chemical compounds. In a chemical equation, reactants are listed on the left hand side of the arrow.

### Stoichiometry

The set proportions in which elements or compounds react with one another.

### Theoretical Yield

The quantity of product obtained from the complete conversion of the limiting reagent in a chemical reaction. This is how much product a reaction would give us if we lived in a perfect world and no errors were allowed.

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