okay, science geeks out there, i need some help, earn your best answer...?

Question

explain this statement "compounds have properties that are always the same but mixtures have variable properties" (no offense about the "geek" term)

Answer 1

A compound with a given formula doesn't change. Here or on the moon or on Vulcan.

A mixture can be and two or more substances in any variation. Look at a piece of granite. About four or five different minerals in the mixture, but in varying degrees on the rock.

Answer 2

A chemical compound is a chemical substance consisting of two or more different chemically bonded chemical elements, with a fixed ratio determining the composition. The ratio of each element is usually expressed by chemical formula. For example, water (H2O) is a compound consisting of two hydrogen atoms bonded to an oxygen atom.

Compounds are a atomic "recipe" for a substance. Various samples of a compound have the same recipe and the same properties.

In chemistry, a mixture is the product of a mechanical blending or mixing of chemical substances like elements and compounds, without chemical bonding or other chemical change, so that each ingredient substance retains its own chemical properties and makeup. While there are no chemical changes in a mixture, physical properties of a mixture, such as its melting point, may differ from those of its components. Mixtures can usually be separated by mechanical means.

Every mixture can have a different "recipe" and different properties, depending on the amounts of substances mixed in.

Answer 3

Elements and compounds are pure substances. Their compositions are always the same, regardless of the source. They also contain a fixed proportion of each composition.

Pure substances are rare though and we usually encounter mixtures of compounds or elements. Unlike elements and compounds, mixtures can have variable compositions. For example, a mixture of sugar and water can have a variable proportion to each other. One can put more sugar or more water.

Mixtures can be homogeneous or heterogeneous. Homogeneous mixtures have the same properties throughout the sample. An example is a thoroughly stirred mixture of salt in water or sugar in water. A homogeneous mixture can also be called solutions. Solutions don't need to liquids. Brass is a solid solution of copper and zinc. The air we breath is a solution of many gases.

A heterogeneous solution consists of two or more regions called phases that differ in properties. There are mainly two types--colloidal dispersions and suspensions. The main difference is only the size of the items being mixed. A mixture of sand and water is an example of a suspension. They do not settle quickly. The particles of sand are constantly being "bumped" by water molecules and continue to stay in suspension for a while.

A colloidal dispersion is a mixture in which the dispersed molecules are very small. The dispersed particles in are small but they may sometimes join together and finally separate on its own from the solvent. Colloidal dispersions usually have an opaque or milky look. If a beam of light is shined through a colloidal dispersion, it will be seen because the particles inside it reflect the light. In solutions, it does not. The light scattering is called the Tyndall effect.

Mixtures differ from compounds by the way they form. For example, a mixture of powered sulfur in powder iron, can be mixed by stirring them together. In the mixture, both elements retain their original properties. It was created using a physical change, not a chemical change, because no new substances formed. Mixtures can be separated into pure substances by physical methods. To separate the mixture, a magnet could easily pull out the iron. When iron and sulfur are put under a chemical reaction, a compound often called "fool's gold" is formed. This compound no longer have the properties of the iron or the sulfur.

Water is another example; it is composed of only H2O, in which the hydrogen and oxygen atoms in a molecule of water always occur in the same ratio and cannot be separated by physical processes. Salt water, on the other hand, is a solution of water containing lots of dissolved minerals. Through a physical process, for example boiling, the water can be separated from those minerals.

Answer 4

A compound has a formula which tells exactly what kind and how many of each atoms are present chemically combined.When or where ever you have a sample of a compound it will be exactly the same.

A mixture has any proportion. Salt water can have a grain of salt or a cup of salt in a cup of water. The components are not chemically combined and can be separated physically. A green salad is a mixture. People make it differently.

Answer 5

I'll explain it with an example that those of us in the northern part of the country are about to experience. Water has a freezing point of 32 degrees F. If you add a little salt to it, the freezing point lowers a little bit to say 25 degrees. If you mix in a little more salt you can lower the freezing point to as low as around 10 - 15 degrees. This is how spreading salt on icy roads gets the ice to melt. By varying the amount of salt in the mixture of salt and water, you can vary the freezing point of the mixture.

Answer 6

Some elements bond such as hydrogen and oxygen. Water is always H2O. Some elements don't bond. They mix. For instance gold and lead don't bond and therefore the mixture of gold and lead will be dependent on how much lead and gold you use.