Chapter 1: Chemistry Review

How to round atomic mass

# drop >5 round up # drop < 5 keep same number # drop is 5 round to closet even number

17. Classify each of the following as an element, a compound, or a mixture: (a) iron (b) oxygen (c) mercury oxide (d) pancake syrup (e) carbon dioxide (f) a substance composed of molecules each of which contains one hydrogen atom and one chlorine atom (g) baking soda (h) baking powder

(a) element (b) element (c) compound (d) mixture (e) compound (f) compound (g) compound (h) mixture 17. (a) element; (b) element; (c) compound; (d) mixture, (e) compound; (f) compound; (g) compound; (h) mixture

density

-use mass and volume to find density -density = mass/volume

13. How do molecules of elements and molecules of compounds differ? In what ways are they similar?

13. Molecules of elements contain only one type of atom; molecules of compounds contain two or more types of atoms. They are similar in that both are comprised of two or more atoms chemically bonded together.

23. When elemental iron corrodes it combines with oxygen in the air to ultimately form red brown iron(III) oxide which we call rust. (a) If a shiny iron nail with an initial mass of 23.2 g is weighed after being coated in a layer of rust, would you expect the mass to have increased, decreased, or remained the same? Explain. (b) If the mass of the iron nail increases to 24.1 g, what mass of oxygen combined with the iron?

23. (a) Increased as it would have combined with oxygen in the air thus increasing the amount of matter and therefore the mass. (b) 0.9 g (23.2 g-24.1 g)

27. Classify each of the following changes as physical or chemical: (a) condensation of steam (b) burning of gasoline (c) souring of milk (d) dissolving of sugar in water (e) melting of gold

27. (a) physical; (b) chemical; (c) chemical; (d) physical; (e) physical

29. The volume of a sample of oxygen gas changed from 10 mL to 11 mL as the temperature changed. Is this a chemical or physical change?

29. physical (because didnt change chemical structure)

An irregularly shaped piece of a shiny yellowish material is weighed and then submerged in a graduated cylinder, with results as shown. mass 51.8429 final Volume= 19.8ml initial volume= 17.1 ml

51.8429/2.7 (final-initial) 19

chemical change

A chemical change always produces one or more types of matter that differ from the matter present before the change. The formation of rust is a chemical change because rust is a different kind of matter than the iron, oxygen, and water present before the rust formed.

Gas

A gas takes both the shape and volume of its container.

Liquid

A liquid flows and takes the shape of a container, except that it forms a flat or slightly curved upper surface when acted upon by gravity. (In zero gravity, liquids assume a spherical shape.) Both liquid and solid samples have volumes that are very nearly independent of pressure.

mixture

A mixture is composed of two or more types of matter that can be present in varying amounts and can be separated by physical changes,

heterogeneous mixture

A mixture with a composition that varies from point to point Italian dressing is an example of a heterogeneous mixture Its composition can vary because we can make it from varying amounts of oil, vinegar, and herbs. It is not the same throughout the mixture

physical property

A physical property is a characteristic of matter that is not associated with a change in its chemical composition

diff between chemical and physical properties

A physical property is an aspect of matter that can be observed or measured without changing it. Examples of physical properties include color, molecular weight and volume. A chemical property may only be observed by changing the chemical identity of a substance.

Solid

A solid is rigid and possesses a definite shape

Balanced or Unbalanced: 2H2 + O2 → 2H2O

Balanced

examples of chemical properties

Examples of chemical properties include flammability, toxicity, acidity, reactivity (many types), and heat of combustion example: Iron combines with oxygen in the presence of water to form rust

19. How are the molecules in oxygen gas, the molecules in hydrogen gas, and water molecules similar? How do they differ?

In each case, a molecule consists of two or more combined atoms. They differ in that the types of atoms change from one substance to the next.

matter what are three types of matter

Matter is defined as anything that occupies space and has mass, and it is all around us. gas, solid, liquid

C' freeze/boil points

On the Celsius scale, 0 °C is defined as the freezing temperature of water and 100 °C as the boiling temperature of water

Fahrenheit scale freeze/boil/pts in between

On the Fahrenheit scale, the freezing point of water is defined as 32 °F boiling temperature as 212 °F. The space between these two points on a Fahrenheit thermometer is divided into 180 equal parts (degrees).

elements

Pure substances that cannot be broken down into simpler substances by chemical changes are called elements. Iron (Fe), silver (Ag), gold (Au), aluminum (Al), sulfur (S), oxygen (O), and copper (Cu) are familiar examples

Chemical Property

The change of one type of matter into another type (or the inability to change) is a chemical property

properties

The characteristics that enable us to distinguish one substance from another

mass

The mass of an object is a measure of the amount of matter in it.

compounds

Two or more different elements chemically combined Pure substances that can be broken down by chemical changes are called compounds. This breakdown may produce either elements or other compounds,

volume

Volume is the measure of the amount of space occupied by an object - The standard volume is a cubic meter (m3) -liter: . A liter (L) is the more common name for the cubic decimeter. One liter is about 1.06 quarts.

homogeneous mixture

also called a solution, appears to be the same throughout. An example of a solution is a sports drink, consisting of water, sugar, coloring, flavoring, and electrolytes mixed together uniformly. Each drop of a sports drink tastes the same because each drop contains the same amounts of water, sugar, and other components

14. How does an atom differ from a molecule? In what ways are they similar?

atom is only one element molecule is made up of two or more both made up of element

an atom is the

atom is the smallest particle of an element that has the properties of that element and can enter into a chemical combination.

examples of physical properties

density, color, hardness, melting and boiling points, and electrical conductivity

12. How does an element differ from a compound? How are they similar?

element cant be broken down into anything smaller compound is made up of elements. it must be separated chemically

pure substances into two classes:

elements and compounds

A pure substance

has a constant composition. All specimens of a pure substance have exactly the same makeup and properties. Examples: Gold (Au), Oxygen (O), Water

10. How does a heterogeneous mixture differ from a homogeneous mixture? How are they similar?

heterogenous mixture= is not the same throughout, if you grab a small sample you want get an even mix. homogenous mixture=solution, same throughout same because they both are mixtures and they are easily separated through filtration.

11. How does a homogeneous mixture differ from a pure substance? How are they similar?

homogeneous mixture- can be filtered, is made up of pure substances variety of compositions pure substance- can only be filtered chemically if it is a compound. has a definite composition Both have the same composition from point to point.

physical change examples

is a change in the state or properties of matter without any accompanying change in its chemical composition (the identities of the substances contained in the matter). We observe a physical change when wax melts, when sugar dissolves in coffee, and when team condenses into liquid water. Also include magnetizing and demagnetizing metals and grinding solids into powders (which can sometimes yield noticeable changes in color).

the law of conservation of mass summarizes

many scientific observations about matter: It states that there is no detectable change in the total quantity (amount) of matter present when matter converts from one type to another (a chemical change) or changes among solid, liquid, or gaseous states (a physical change). *the mass of the system must remain constant over time

metals nonmetals metalloids

metals (elements that conduct well), nonmetals (elements that conduct poorly), metalloids (elements that have properties of both metals and nonmetals).

molecule

molecule consists of two or more atoms joined by strong forces called chemical bonds. The atoms in a molecule move around as a unit a molecule may consist of two or more identical atoms, as in the molecules found in the elements hydrogen, oxygen, and sulfur or it may consist of two or more different atoms, as in the molecules found in water

9. What properties distinguish solids from liquids? Liquids from gases? Solids from gases?

solids= ridid, definite shape, can measure volume liquids= volume but not defnite shape,can change their shape (flow) gases= dont have volume and dont have definite shape. fill up the container that they are in. can undergo large volume changes as pressure changes;