An Introduction to Mixtures and Solutions

Sixth Grade ScienceKit #2

Gain experience with the concepts of mixture, solution, concentration, saturation, chemical reaction.

Apply an operation definition to determine the relative concentrations of solutions.

Acquire vocabulary associated with chemistry and the periodic table.

Be introduced to the concept that all matter is made of very small particles called atoms and that atoms combine to form molecules.

Goals for this unit

Everything in the universe can be put into one of two categories: matter or energy

Matter – is the material of the universe Energy – is the drive that makes things happen

Chemistry – is the study of the properties, relationships, and the interactions of matter and the energy changes that result from chemical interactions.

Background Information: The Basis Of It All

Matter is made up from the 92 naturally occurring chemical elements.

Some are familiar substances: sulfur, silver, hydrogen, and iron.

Some are rare substances: erbium, gadolinium, lutetium, and rhenium.

What is matter made of?

The elements themselves are made up of atoms, which are the smallest particles into which an element can be divided yet retain all of its characteristics.

What are the elements made of?

It is thought that the Earth’s core consists of nickel, iron, and other heavy metals.

The Earth’s crust makes up 98% of the minerals: oxygen, silicon, aluminum, iron, calcium, sodium, potassium, and magnesium.

There is hydrogen in the water on earth. By mass, about 75% of the Earth’s crust

(land, oceans, and atmosphere) consists of oxygen and silicon.

Background facts…

11 elements are common in living organisms, with hydrogen and oxygen the most abundant.

In the human body, 97% of the atoms are nitrogen, oxygen, carbon or hydrogen.

The rest of those 11 elements include: sulfur, phosphorus, calcium, sodium, potassium, magnesium, and chlorine.

Background facts…

Atoms are not usually found in pure (elementary) from, but are attached to other atoms in stable associations of molecules.

A molecule that contains atoms of more than one element is called a compound.

Compounds can be simple, composed of two or three atom units, like water, salt and carbon dioxide or they can be complex, like hemoglobin and chlorophyll.

Background facts…

Water moleculeCarbon Dioxide Molecule

Hemoglobin Molecule

Chlorophyll Molecule

Background facts…

On our planet, matter appears in only three states—solids, liquids, and gas.

Examples: Solid – A piece of gold Liquids – Water Gas -- Oxygen

Changes in state: Often when a solid is heated, it melts and

becomes a liquid. If heating continues, the liquid might vaporize and become a gas. When water loses enough heat, it turns to a solid called ice. When water collects more heat, it evaporates and turns into a gas called water vapor.

Background facts…

Mixture – When two or more kinds of matter are combined.

Simple mixtures include: sand and water, oil and vinegar, nuts and bolts, coleslaw, and rocky-road ice cream.

Mixtures can be made with any combination of gases, liquids, and solids.

Putting different kinds of matter together

Yes. Mixtures can be separated using mechanical means, such as hand separation, screening, and filtering. The components of a mixture are not changed by mixing with other materials.

Can mixtures be separated once they’re together?

Dissolving – when a solid disappears in a liquid (like salt in water)

Solution – The liquid that is left after a solid was dissolved in it.

Solvent and Solute – When a solid dissolves in a liquid, the liquid is the solvent and the solid material is the solute.

Evaporation – When the liquid changes to a gas, the gas moves into the air, and the solid is left behind.

Other terms to know…

Because of the materials we will be working with, you must abide by the following rules. Never put anything in your mouth. Do not taste

anything. Do not smell any unknown materials. Avoid touching your face, mouth, ears, or eyes while

working with the chemicals. Do not mix unknown chemicals just to see what might

happen. Always wash your hands immediately after using

chemicals.

Safety First

Clean up spills immediately. Clean up your work space after each investigation. Be careful when using sharp or pointed tools. Report all accidents, even small ones, to your teacher. Follow directions and ask questions if you’re unsure of

what to do. Behave responsibly during the science investigations.

IF YOU DO NOT FOLLOW THESE RULES, YOU WILL NOT BE PERMITTED TO PARTICIPATE IN THE LABS.

Safety First