CHEM EXAM: Equations and definitions

Density

density = mass/volume

calculating number of neutrons in an atoms

N= A-Z

number on neutrons = mass number- atomic number

calculating avg atomic mass of the isotope of an element

atomic mass = (Isotopic mass)(fractional abundance of isotope)

NA =

1 mole(Avogadro’s number) 6.022 × 10²3 (4 sgf)

calculating percent yield

% yield = actual yield/theoretical yield x 100

define molarity

moles of solute/liters of solute or M= mol solute/L solute

Diluting a concentrated solution

or use M instead of C ex: M1 V1= M2 V2

Boyles Law

Volume + pressure relationship:

Charles law

Volume + temp relationship:

Amonton’s law/Gay Lussac

Pressure and temp relationship:

Avogadro’s law

Volume and amount relationship:

Dalton’s law of partial pressures

Pi=XiP total and Xi=ni/n total

volatile molar mass:

M=mRT/(PV)

Avogadros Number

Solution =

soulte + solvent mixture

EX: of solution

NaCl

Know trends for ionic charge

rules for counting sig figs

rules for calculating with sig figs

Definiton equations for density

density= mass/volume g/ml or g/cm³ g/L

defintion equation for molarity

moles of solute(M)/Liters of solution mo/L

What term relates density and molarity?

molar mass g/mol

Element name and symbol

Molybdenum - Mo

Density( Units and conditions of your element)

10.223 g/cm³ → conditions at 20 degrees Celsius or 293.15 K

Melting/freezing point of element(unit)

2623 degrees Celsius ( 4753 degrees F, 2896 K)

Provide brief description of history, properties, and uses of your assigned element

Discovered in 1778 by Carl Wilhem Scheele. Molybdenum is a silvery-white, hard transition metal. Because of its extremely high melting point and strength at high temperatures it's used in steel alloys, industrial catalysts, electrical contacts, and aerospace applications. Mo is pretty cool!

1 inch =

2.54 centimeters

1 mL=

1 cm³

0 degrees C=

273.15 K

1 atm =

760 torr

1 torr=

1 mmHg

1 atm =

101,325 Pa

Molar Volume of an Ideal Gas at STP 1 mol=

22.4 L

1 L=

10³ mL

Useful r value

L= 8.314/0.08206