Honors Chemistry study guide

Divisions of Chemistry

1.Organic 2.Inorganic 3.Analytical 4.Physical 5.Biochemical

During a filtration or distillation experiment, we separate a mixture into its individual components. Do the chemical identities of the components of the mixture change during such a process? Explain.

No the chemical identities of each of the different parts stay the same in their own property even when they are separated.

The boiling of water is a . . .

physical change because the gaseous water is chemically the same as the liquid.

Homogenous

the same throughout the entire mixture ex/hand sanitizer

If you place a glass rod over a burning candle, the glass turns black. What is happening to each of the following (physical change, chemical change, both, or neither) as the candle burns?

the wax- physical change-solid to liquid chemical change-burned to CO2 + H20 + heat + carbon as seen by black on rod the wick- neither - wick does not change, merely provides conduit for wax to flame rod- physical only as carbon is deported

mixture

variable combination of 2 or more pure substances

Law of multiple proportions

Elements can combine in different ratios to form different compounds ex/ carbon + oxygen = carbon dioxide

What is a compound? What is a compound composed of? What is true about the composition of a compound, no matter where we happen to find the compound?

A compound is the composition of two or more elements in a fixed ratio A compound is composed of two or more elements It will always be made up of the same elements for example, water will always be made up of hydrogen and oxygen

If iron filings are placed with excess powdered sulfur into a beaker, the iron filings are still attracted by a magnet and could be separated from the Sulfur with the magnet. Would this combustion of iron and sulfur represent a mixture or a pure substance?

A pure substance because when the two substances are mixed together, they can still be taken apart again through the magnet. They never actually become a mixture.

Matter

Anything that contains mass

Is brass a mixture or a solution? Why?

Brass is a homogenous mixture made up of 2 elements, copper and zinc.Instead of the mix being chemically combined(which would make a compound), it is physically combined together.

Definition of Chemistry

Chemistry is the study of the composition of matter and the changes they undergo

extensive

Depends on the amount of matter present ex/ volume, mass, and length

In a common laboratory experiment in general chemistry, students are asked to determine the relative amounts of benzoic acid and charcoal in a solid mixture. Benzoic acid is relatively soluble in hot water, but charcoal is not. Devise a method for separating the two components in the mixture.

First you put the mixture in hot water and allow the benzoic acid to separate. Next funnel it and then see what's on the funnel paper. Lastly, heat the leftover water and see what's left after it evaporates.

Consider three 10 g samples of water: one as ice, one as liquid, and one as vapor. How do the volumes of these three samples compared with one another? How is the difference in volume related to the physical state involved?

Gas would have the most volume because it expand in any given area and mold to its shape. The solids volume is the next largest because when water freezes it becomes bigger. Lastly is the liquid that is the smallest

.If a piece of hard white blackboard chalk is heated strongly in a flame, the mass of the piece of chalk will decrease, and eventually the chalk will crumble into a fine white dust. Does this change suggest that the element is composed of an element or a compound?

It is a compound because when one heated the chalk, it caused a change in physical properties and mass.

Oxygen forms molecules in which there are two oxygen atoms, O2. Phosphorus forms molecules in which there are four phosphorus atoms, P4. Does this mean that O2 and P4 are "compounds" because they contain multiple atoms? O2 and P4 react with each other to form diphosphorus pentoxide, P2O5. Is P2O5 a "compound?" Why or why not?

O2 and P4 are elements because they are made up of the exact same atoms and are not being chemically combined together P2O5 is a compound because they are being chemically combined together

States of matter

Solid -very low kinetic energy Liquid -low kinetic energy Gas -high kinetic energy Plasma -very high kinetic energy

Chemical Change + example

changes the identity of a substance; products have different properties ex/rusting iron, burning a log

During a very cold winter, the temperature may remain below freezing for extended periods. However, fallen snow can still disappear, even though it cannot melt. This is possible because a solid can vaporize directly, without passing through the liquid state. Is this process a physical or a chemical change?

This is a physical change because the water isn't changing into another substance. It is turning into water vapor which is still water.

When water boils, you can see bubbles rising to the surface of the water. Of what are these bubbles made?

Water Vapor because boiling water is physically changing, but the other gases and air change the formation of the substance chemically.

Law of Definite Composition

a given compound always contains the same, fixed ratio of elements

Physical Change + example

a substance does not change into another substance, it keeps its same identity; properties remain the same ex/dissolving in water, grinding of spices

Classify the following mixtures as homogenous or heterogenous a. dirt from a corn field b.flavored sports drinks c.nut party mix d.pepperoni and sausage pizza e. air

a. Hetero b. Homo c. Hetero d. Hetero e. Homo

Classify the following as mixtures or pure substances a. the vegetable soup you had for lunch b. The fertilizer your dad spreads on the front lawn in the spring c. The salt you sprinkle on french fries d. the hydrogen peroxide you cleaned a cut finger with

a. mixture b. pure substance c. pure substance d. mixture

element

composed of identical atoms ex/copper wire

compound

composed of two or more elements in a fixed ration. ex/table salt

intensive

depends on the identity of the substance, not the amount ex/ color, density, and melting point

What are two characteristic properties of matter?

has mass it occupies space

What is the chief factor that determines the physical state of a sample of matter?

how fast the particles are moving; forces among particles in the matter

If the combination of Iron filings and sulfur in Question 25 is heated strongly, the iron reacts with the sulfur to form a solid that is no longer attracted by the magnet. Would this still represent a "mixture?" Why or why not?

it is not because it is now chemically combined and is now a compound

Heterogenous

made up of different substances throughout mixture can be taken apart ex/pizza