Substances/Mixtures

1. Examine the objects in the beaker. 2. Sort them into groups. 3 1. Examine the objects in the beaker. 2. Sort them into groups. 3. Each item should be grouped with similar items. 4. Describe the difference between the unsorted beaker and the sorted groups of objects. 5. In your own words, define a pure substance and a mixture.

What are pure substances? Pure substance = Matter that contains only one type of particle. Examples Elements like hydrogen and oxygen Compounds like water (when pure not tap)

What are pure substances? Characteristics The particles cannot be separated by physical means Every sample has the same properties Every sample has the same ratio of atoms

What are pure substances? Kitchen Evaporated sea water Underground mine   NaCl NaCl NaCl 1:1 1:1 1:1 Crystal Crystal Crystal Clear/White Clear/White Clear/White Melts at 801oC Melts at 801oC Melts at 801oC

What are mixtures? Most things in the world are not pure, instead they’re mixtures Mixture = Matter made of two or more pure substances that are not chemically combined

What are mixtures? Characteristics Usually easy to separate into its components Each pure substance in a mixture keeps its own properties The parts of a mixture are not combined in a set ratio

What are mixtures? Characteristics Usually easy to separate into its components Each pure substance in a mixture keeps its own properties The parts of a mixture are not combined in a set ratio

Two types of Mixtures Heterogeneous You can see the different parts Examples: soil and salad

Two types of Mixtures Homogeneous Evenly mixed so that you can’t see the different parts (uniform) Example: sugar dissolved in water

Two types of Mixtures Homogeneous Another example is a solution Salt dissolving in water (solid in a liquid) Nitrogen dissolving in oxygen (two gases) Copper dissolving in zinc (two liquefied metals)

Pure substances vs. Homogeneous vs. heterogeneous What’s what? Pure substances vs. Homogeneous vs. heterogeneous

Chicken soup

Lemonade

Steel

Gold

Chunky peanut butter

Blood

Chocolate chip cookie

Sugar

Air

Coffee