Chemistry 2 yousef berbar
Transcript of Chemistry 2 yousef berbar
C h e m I s t r y
Sect ion threeBy:
Youssef Berbar
Mole : 6.022 x 10^23 units, the number equal to the number of carbon atoms in exactly 12 g of pure C 12
Molar mass : the mass of one mole of a pure substance.
Avogadro no : 6.022 x 10^23
How to calculate : How to know atomic mass ?! If we have a
element that has 2 isotopes and we want to calculate the atomic mass we follow the following rule :Ratio of isotope one * its mass + ratio of isotope 2 * its mass = no its unit is Amu , also it is written under the element symbol in the periodic table
Molar mass = Molecular mass = atomic mass in its magnitude
What is the difference between molar , molecular and atomic massBoth of them are equal in magnitude but the unit of
atomic mass is Amu and the unit of molar and molecular mass is g / mole
Another example what is the molar mass of co2 : 12 g / mole
calculate the molecular mass of water (H2O) (1.01 amu + 1.01 amu + 16.00 amu) = 18.02 Amu or 18.02 g / mole
Molar mass of element is no. g / mole . What means ?Molar mass = mass / Avogadro no ( no of moles )No of moles = mass / molar mass
Some definitions standard temperature and pressure
(STP):standard temperature is 273.15 kelvins and standard pressure is 760 mm Hg ( 1 atm).
Stoichiometry : the study of the relationships (mass-mole-volume) among substances involved in chemical reactions.
dimensional analysis : a name for “equivalent measures.” A method for solving problems that involves canceling units.
The equation also shows that 2 mol C8H18 react with 25 mol O2 to form 16 mol CO2and 18 mol H2O.
No of mole = mass / molar mass Density = mass / volume
Problem one
Solution of problem one
Mole ratio =
We have 312 moles of ammonia so ,
Problem two
Solution of problem two
Problem Three
Solution of problem Three
Problem four
Solution of problem four
Thanks for listeningYoussef Berbar