Mixtures and Pure Substances

Pure Substances vs. Mixtures

Key Definitions

• Pure Substance: A container filled with only one type of element or only one type of compound.
• Mixture: A container that does not contain only one type of element or only one type of compound.
• Element: A substance consisting of only one type of atom.
• Compound: A substance consisting of two or more different types of atoms bonded together.
• Molecule: Two or more atoms held together by chemical bonds.

Container Examples

Example 1

• Container 1 contains nitrogen atoms and hydrogen atoms.
• Since there is more than one type of element (nitrogen and hydrogen), it is a mixture.

Example 2

• Container 2 contains only water molecules ($H_2O$).
• Since it contains only one type of compound (water), it is a pure substance.

Example 3

• Container 3 contains hydrogen molecules ($H_2$) and carbon atoms (C).
• Since there is more than one type of element (hydrogen and carbon), it is a mixture.

Additional Examples

Example 4

• Container 1 contains carbon atoms (C) and nitrogen atoms (N).
• Since there is more than one type of element (carbon and nitrogen), it is a mixture.

Example 5

• Container 2 contains only nitrogen molecules ($N_2$).
• Since it contains only one type of element (nitrogen), it is a pure substance.

Example 6

• Container 3 contains a compound and hydrogen molecules ($H_2$).
• Since it contains both a compound and an element and not just one type of compound, it is a mixture.

Example 7

• Container 4 contains nitrogen atoms (N) and carbon atoms (C).
• Since there is more than one type of element (nitrogen and carbon), it is a mixture.

Key Points to Remember

• To determine if a container holds a pure substance or a mixture, simply examine the contents.
• If the container has the same type of element or same type of compound, it is a pure substance.
• If the container has different types of elements or compounds, it is a mixture.