Year 7 Chemistry
Chemical Mixtures
Chemical mixtures contain two or more distinct chemical components in either a heterogeneous or homogeneous state. They do not have a constant chemical composition and cannot be represented by a chemical formula. The substances in a mixture, regardless of how thoroughly they are mixed, do not react with each other chemically. A heterogeneous mixture consists of substances that have distinct and different phases, such as ice cubes and water. Homogenous mixtures, in contrast, consists of substances in a single phase, as in a mixture of gases.
Solutions and Mixtures. (2000). In World of Chemistry. Detroit, MI: Gale. Retrieved from http://link.galegroup.com/apps/doc/CV2432500457/SCIC?u=61wa_corpus&sid=SCIC&xid=c41f8fbd
Additional Resources
- What is a Mixture in Chemistry? Definition and ExamplesYou may have heard the term mixture used in reference to chemistry or cooking. Let's take a look at what a mixture is.
- What is a Mixture in Chemistry?The scientific definition of a mixture is more complicated than the definition you use in everyday life. The degree of combination, the presence or lack of chemical reactions, the size of the particles and the distribution of one substance among another all determine whether something fits the scientific characterization of a mixture and what type of mixture it is.
- MixturesA mixture is a jumble of different things. Soil is a mixture of sand, clay, stones, roots, and plant and animal remains. The air is a mixture of different gases. Seawater contains a mixture of different chemical compounds in solution.
Chemical Changes
Categories of Mixtures
There are two main categories of mixtures: homogeneous mixtures and heterogeneous mixtures. In a homogenous mixture all the substances are evenly distributed throughout the mixture (salt water, air, blood). In a heterogeneous mixture the substances are not evenly distributed (chocolate chip cookies, pizza, rocks).
Ducksters Education Site. (n.d.). Chemistry for Kids: Chemical Mixtures. Retrieved from https://www.ducksters.com/science/chemistry/chemical_mixtures.php
Mixtures
What do students need to know about mixtures and solutions?
- Mixtures are materials that contain two or more chemical substances dispersed among each other (mixed together).
- If no chemical reaction occurs when two materials are mixed, they form a mixture. The chemical properties of the components don’t change.
- Mixtures can be separated by physical methods.
- There are two general types of mixtures: homogeneous and heterogeneous.
- Homogeneous mixtures: the particles of the substances are mixed together (there is no clumping of the particles) – eg air.
- Solutions are homogenous mixtures: particles of one substance (the solute) are mixed together with the particles of another substance (the solvent) – eg salty water.
- Heterogeneous mixtures: large aggregations (clumps) of the substances are mixed together – eg emulsions like oil in water.
Paterson, D. (2018). How to Teach Mixtures and Solutions. Retrieved from https://eic.rsc.org/cpd/mixtures-and-solutions/3008735.article
Chemistry for Dummies
Chemistry for Dummies® by ISBN: 9781118007303Publication Date: 2011-05-31
