Mixtures

Mixtures

Physical blends of substances.

(How most matter exists)

Multiple Choice

True or False.

A pure substance has uniform composition and properties.

• True

• False

Multiple Choice

True or False.

A pure substance can be an element or a compound.

• True

• False

Multiple Choice

True or False,

A sample of matter that contains more than one type of atom must be a mixture.

• True

• False

Mixtures

• Physical combination of 2 or more pure substances. They are not chemically combined, just near each other.

• The ratio of components can be varied   (Ex:  5% salt solution vs a 10% salt solution)

• Each component retains its original properties

• The components can be separated by physical means

• Mixtures are either heterogeneous or homogeneous

Poll

Which is better?

• Iced tea with lots of sugar

• Iced tea with only a little sugar

The proportions (a.k.a. the ratio) of the components can be varied

By Contrast: In a compound the ratio of atoms is fixed.

Can be separated by physical means.

After separation, each component retains its original properties.

Heterogenous mixtures

vs.

Homogeneous mixtures

(how evenly distributed the particles are)

Multiple Choice

Which type of mixture is a salad?

• heterogeneous

• homogeneous

Heterogeneous

Mixtures

• hetero means "different"

• Particles are not evenly distributed.

• From the same mixture, one sample will look different from another sample.

• Components can often be visually distinguished.

Homogeneous

Mixtures

• homo means "same"

• Particles are evenly distributed.

• Samples taken from the mixture are consistent with each other (uniform composition)

• Components cannot be visually distinguished.

• Also known as solutions

Solutions

• homogeneous mixtures

• main component is called the solvent

• dissolved component(s) are called solute

• When water is the solvent, called an aqueous solution

• (aq) is shorthand for aqueous

Aqueous Solution Example

Copper sulfate dissolved into water.

shorthand (chemical formula)

CuSO_{4 (aq)}

copper ions and sulfate ions will be evenly distributed in between the water molecules.

Common examples of homogeneous mixtures

(aka Solutions)

• Salt water , NaCl _(aq)

• sugar water , C₆H₁₂O_{6 (aq)}

• air

• metal alloys (brass, bronze)

Multiple Choice

Which of the following must be a mixture?

• gas

• liquid

• solid

• solution

Multiple Choice

When water is the main component of a homogeneous mixture it is called a ...

• heterogeneous aqueous

• aqueous solution

• water bath

• agua party