CHM2045 Test #1

Matter

Anything that occupies space and has mass

-Consists of atoms and molecules in motion (kinetic energy)

Dimensional Analysis

Metric Conversions

Physical Properties

A characteristic of a pure substance that can be observed without changing it into another substance.

Atom

The smallest particle of an element that retains the characteristic chemical properties of that element.

True or False

Increasing temperature corresponds to faster and faster motions of atoms and molecule

True

-In part of kinetic energy of substances

Mass

Measure of the quantity of matter that an object contains

Many experiments are conducted at 298 K. What is the temperature in Celsius?

273.15 + C = K

273.15 + C = 298K

C = 298K - 273.15

C = 24.85

How many miles are covered in a 15km race?

(1 mile= 5280 ft, 12 in= 1 foot, 1 inch = 2.54 cm)

15km = 1000 m/ 1 km 100 cm/ 1 m 1 in/ 2.54 cm 1 ft/ 12 in = 49,212.6 ft 1 mile/5280 ft = 9.3

Matter can be classified by its physical state(s)....

-Gas

-Liquid

-Solid

Matter can be classified by its composition....

-Element

-Compound

-Mixture

Homogeneous Mixture

A mixture that is so evenly mixed that you can't see all of the different parts. (Uniform composition)

-Ex. Air, kool-aid

Elements

-Consists of only one type of atom

-They cannot be decomposed or further simplified by ordinary means

-Often be distinguished by their color and their state at room temperature

-EX: Sodium, Helium

Heterogeneous Mixture

A mixture that is not uniform in composition; components are not evenly distributed throughout the mixture

-Can be separated by filtration

Compounds

-Combination of two or more elements in a definite reproducible way

-EX: Water (H2O)

Periodic Table

A table that shows the elements, their atomic number, symbol, and average atomic mass; elements with similar chemical properties are grouped together.

-118 recorded elements at this time

-Originally arranged by increasing atomic mass. 1869 Mendeleev

H

Hydrogen

Li

Lithium

Na

Sodium

K

Potassium

Rb

Rubidium

Cs

Cesium

Be

Beryllium

Mg

Magnesium

Ca

Calcium

Sr

Strontium

Ba

Barium

Ra

Radium

Ti

Titanium

4+ charge

Cu

Copper

+1 or +2 charge

Cd

Cadmium

+2 charge

Pb

Lead

2+ charge

Bi

Bismuth

+3 charge

Fe

Iron

+2 or +3 charge

B

Boron

C

Carbon

N

Nitrogen

O

Oxygen

F

Fluorine

Al

Aluminum

Si

Silicon

P

Phosphorus

S

Sulfur

Cl

Chlorine

Ne

Neon

He

Helium

Ar

Argon

Kr

Krypton

Br

Bromine

I

Iodine

Xe

Xenon

Rn

Radon

At

Astatine

Pb

Lead

Cu

Copper

Ag

Silver

+1 charge

Au

Gold

Hg

Mercury

2+ charge

Plutonium

Pu

Technetium

Tc

Tellurium

Te

Sn

Tin

2+ charge

Kr

Krypton

Electronic Current is measured by what?

Ampere (A)

Alkali Metals

Group 1 on Periodic Table

-1 electron in outer level, very reactive, soft, silver, shiny, low density

-Lithium, Sodium, Potassium, Rubidium, Cesium, Francium

Alkaline Earth Metals

-Metallic elements in group 2 of the periodic table which are harder than the alkali metals and are also less reactive

Halogens

Contains nonmetals, 7 valence electrons in it's outermost energy level. Very reactive

Noble Gases

Elements in group 8A of the periodic table

-Have no charge and are gases under normal conditions.

-Helium, Neon, Argon, Krypton, Xenon, Radon

Mixtures

A combination of two or more pure substances

1. Homogeneous

2. Heterogeneous

-When separated, the components of both types of mixtures yields pure substance

Pure Substance

A sample of matter, either a single element or a single compound, that has definite chemical and physical properties and cannot be further purified

-Compounds and elements

Which of the following is not characteristic of a pure substance?

1 Has uniform composition throughout

2 Has a fixed melting temperature

3 Can be separated into two other pure substances

Can be separated into two other pure substances

Solutions

A mixture where substances are distributed evenly (homogeneous).

-Has a solvent & solute

-Solid/Liquid (sugar in water)

-Liquid/liquid (gasoline)

-Solid/solid (Brass)

-Composition can vary: Amount of solute in solvent!! There is no fixed ratio

Solute

Minor component of a solution

Solvent

Substance that contains solutes

Chemical Compounds

Composed of two or more elements

-All are made up of molecules or ions

1. Ionic: Sodium Chloride

2. Molecules: Water, Carbon dioxide, Octane, Sugar, etc.

-There is a fixed ratio with the compositions!!

Water

H2O

Methane

CH4

Ammonia

NH3

Carbon dioxide

CO2

Are compounds just mixtures of elements?

1. Compounds have different properties than elements

2. Fixed composition ratio (definite proportions): definite % of composition by mass

EX: Iron Pyrite FeS2 ------> 46.55 % iron and 53.45% sulfur

FeS2---> 1 Fe= 55.845

2 x S= 2 x 32.066 = 64.132

FeS2----> 119.977

What physical properties can be evaluated without changing the composition of the material?

Color, Odor, Density, Melting point, Thermal conductivity, Volume, Hardness

Extensive Properties

(Mass) Depends upon the amount of substance

Intensive Properties

(Density) Does not depend on amount of substance

-Temp, boiling point, melting point,density, hardness

Density

D=M/V

-A measure of how much mass is contained in a given volume.

Object: mass=20.4558, V=2.13 cm3. Give the Density

d=9.60 g/cm3

Mercury density at 20 C is 13.570 g/mL. What is the mass of 107.3 mL of mercury?

d=m/V

m=d*V

m=(13.570 g/mL)*(107.3 mL)

m=1456 g

m=1.456 * 10^3 g

Density of acetic acid at 20 C is 1.05 g/mL. What volume do I need to have 275 g of acetic acid?

d=m/V

V=(275g)/(1.05 g/mL)

V=262 mL

Chemical Changes

One substance or more are transformed into one or more new substances

-Involves a change in chemical composition

-Results in a change in composition or structure

-Reactants-------> Products

-2H2 (Hydrogen gas) + O2 (oxygen) --------> 2 H2O (water)

Energy

Capacity to do work

1. Kinetic: energy associated with motion

-EX: ball rolling down hill, movement of electrons in a conductor (electrical energy)

2. Potential: results from an object's position

-EX: Gravitational like a waterfall, ball being held at certain height; Energy stored in extended spring; Energy stored in molecules (chemical energy food); Nuclear fission

-SI unit: joule (J)

kJ= kilojoule= 1000 J

Conservation of Energy

-In a physical or chemical change, energy is conserved

-Total energy content is the same after an event as it was before

The Seven SI Base Units

Mass=kg

Length=M

Time=second

Temperature: Kelvin

Amount of substance: Mole

Electric Current: Ampere

The distance between an O and H atom in a water molecule is 95.8 pm. What is this distance in nanometers (nm)?

1 pm = 1 X 10^-12 m and 1 nm = 1 X 10^-9 m

95.8 pm X 1 X 10^-12/ 1 pm = 9.58 X10^-11 m

9.58 X 10^-11 m X 1 nm/1 X 10^-9 m = 9.58 X 10^-2

Giga-

10^9

Mega-

10^6

Kilo-

10^3

Deci-

10^-1

Centi-

10^-2

Mili-

10^-3

Micro-

u+q lookin thing

10^-6

Nano-

10^-9