Pure Substances vs Mixtures
Concept 5: Pure Substances vs. Mixtures
Success Criteria & Vocabulary
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I can identify and describe the differences between pure substances and mixtures.
I can differentiate between elements, compounds, and mixtures.
Click this drop-down menu to see the list of Vocabulary.
Atom: Smallest unit of matter - all matter is made of this.
Bonds: Attractive forces that hold particles together.
Compound: Substance that consists of two or more different elements bonded together.
Element: Substance that consists of only one type of atom.
Mixture: Substance that consists of different elements/compounds that are not chemically bonded together.
Pure substance: Substance that consists of only one type of element or compound.
Learn the 6 keywords using Quizlet:
Worksheet - C5: Pure Substances vs. Mixtures
Complete Education Perfect:
Task called 'Pure Substances, Compounds, & Mixtures'.
Pure and impure substances
Blood as a mixture
indigenous art using mixtures.
Concept 5: Support Notes
There are approximately 130 different ELEMENTS, but there are many millions of substances. This is because most substances around us is made up of combinations of elements. These combinations of elements can either be COMPOUNDS or MIXTURES.
PURE SUBSTANCES are made up of only one type of ELEMENT or COMPOUND. For example: water, oxygen gas, nitrogen gas, copper wire.
Pure substances can either be an element or a compound.
Elements are substances that are only made up of one type of ATOM.
Compounds are substances that have two or more elements joined together by chemical BONDS.
If a solid, liquid, or gas is made up of only one type of atom, we say it is an element. For example, consider a tripod made up of iron.
If two or more different ELEMENTS have chemically reacted together and BONDED, then they form a COMPOUND. So, compounds are different to elements because they contain different ATOMS. Here are some examples:
Methane (CH4) is 1 carbon and 4 hydrogen atoms chemically bonded together.
Sodium chloride (NaCl) are repeating units of 1 sodium and 1 chlorine atom chemically bonded together.
Glucose (C₆H₁₂O₆) is 6 carbon, 12 hydrogen, and 6 oxygen atoms chemically bonded together.
Carbon dioxide (CO2) is 1 carbon and 2 oxygen atoms chemically bonded together.
The name of a chemical compound tells us about the elements that it is made from. The formula of the compound tells us:
Which elements are in the compound.
The proportions of each element present.
If different elements and/or COMPOUNDS are in the same physical space and not chemically BONDED, then they form a MIXTURE.
Mixtures are substances that contain different types of ELEMENTS or COMPOUNDS that are NOT chemically joined together. For example: sea water, orange juice, gasoline, fireworks, cement, mud.
The big difference between a compound and a mixture is that compounds have ONE type of molecule joined together and is therefore very hard to physically separate. Whereas mixtures have MORE THAN one type of molecule that is not joined, and therefore is very easily separate physically.
Not examined: There are two types of mixtures:
Heterogeneous mixtures are those that have particles that are distributed non-uniformly. Usually, individual components are easy to see with the naked eye.
Homogeneous mixtures are those that have particles that are distributed uniformly. The individual components are not visible with the naked eye.
Liquid Solutions as Mixtures
Solutions are made from a solute dissolved in a solvent.
A solvent is a substance (such as water) that can dissolve a solute. The solvent 'pulls apart' the bonds that hold the solute particles together and the solute particles diffuse (spread randomly from an area of high concentration to an area of low concentration) throughout the solvent to create a solution.
The solution is a homogeneous mixture because it is a mixture with evenly spread solvent and solute particles. These particles can be physically separated by evaporation.
When solids mix into a liquid and can no longer be seen, they have dissolved. Often the particles of the solute seemed to have disappeared, but they are all still present. They are now just in very small particles too small to be seen by eye.
Many drinks we purchase are solutions. Most of them are solutions of mainly sugar (solute) and water (solvent) with a small amount of flavouring, colouring, and some minerals mixed in. We do not 'see' the sugar because it is dissolved into the water and becomes too small to see. This means a lot of sugar can be hidden in the liquid and we are unaware of the amount of sugar we take in, even in so-called healthy sports drinks.