Mixtures
Chemistry: IB Diploma Higher Level, topic 1.6.4
Mixtures
A mixture is composed of two or more types of matter that can be present in varying amounts and can be separated by physical changes, such as evaporation.
Mixtures
- Mixtures are made of 2 or more substances (elements or compounds) that haven't been chemically combined.
- Mixtures can be separated and their chemical properties don't change because they have been mixed with another substance.
- Mixtures contain molecules or formula units of at least two different types.
- For example, a solution of saltwater is a mixture of salt (NaCl) and water (H2O).
- Pure substances contain molecules or formula units of just one type.
Mixtures in everyday life
- Mixtures are common in everyday life:
- Air is a mixture of gases, including oxygen, nitrogen and carbon dioxide.
- A bowl with both pasta and vegetables in is a mixture.
- This is because there have been no chemical reactions between the vegetables and the pasta.
Heterogeneous mixtures
- A mixture with a composition that varies from point to point is called a heterogeneous mixture.
- Italian dressing is an example of a heterogeneous mixture.
- Its composition can vary because it may be prepared from varying amounts of oil, vinegar, and herbs.
- It is not the same from point to point throughout the mixture—one drop may be mostly vinegar, whereas a different drop may be mostly oil or herbs because the oil and vinegar separate and the herbs settle.
Homogenous mixtures
- A homogeneous mixture, also called a solution, exhibits a uniform composition and appears visually the same throughout.
- An example of a solution is a sports drink, consisting of water, sugar, coloring, flavoring, and electrolytes mixed together uniformly.
- Each drop of a sports drink tastes the same because each drop contains the same amounts of water, sugar, and other components.