Overview of fundamental Concepts
Atomic excess weight
The atomic weight of element: is a mass of an atom of that element depending on a mass of accurately 12 for the carbon isotope C12.
Molecular or formula weight
It's the sum of atomic weight loads of the factors that comprise molecule from the substance i. e since given by the molecular formulation. Mwt of water (H2O) =2(1. 008) +1(16. 00) =18. 02
Mwt of hydrogen (H2) =2(1. 008) =2. 016
These weight load are all in accordance with the mass of C12 atom while 12. 1000 with (SI) system of products. Molecular weight is stated by g/mole
Calculate the molecular fat of: --
b) CaSO4. 7H2O
Ans: a) 142. 04 g/mol b) 262. 25 g/mol.
The mole unit
The mole (or g. gopher or gram molecular weight) can be defined as the amount of the compound that contains volume of constitutional species (molecules) equal to that precisely 12 grams of 12C.
This quantity of molecules is known as " Avogadro s" number which is corresponding to 6. 023Г—1023molecues/mole.
Number of moles is calculated as: -
Calculate the quantity of moles in 500mg of sodium tungstate (Na 2WO4). Given: Na= 22. 99 W= 183. 85 O= 16
Mwt of Na2WO4= 2(22. 99) + 183. 85 + 4(16) =293. 83 g/mol.
No . of moles =
= 0. 00170 mol =1. six m mol
Calculate the mass of 0. two hundred fifity mmol. of ferric oxide (Fe2O3)? Fe= 55. 845 Mwt of Fe2O3 = 159. 69 mg/mmol
Mass = zero. 250 mmol Г—159. 69 mg/mmol =39. 3 magnesium
A) Determine the number of skin moles of K2CO3 that contains 117. 3 g. of potassium
B) Determine the mass in grams of other elements in such chemical substance? K=39. 1 O =16 C =12.
g. atom of K sama dengan
Each skin mole of K2CO3 contains 2g. atom of K
ZERO of moles of k2CO3 =
Mass of Oxygen = g. atom of oxygen Г— atomic excess weight =1. 5Г—3Г—16 =72g. Mass of carbon = g. atom of carbon Г—atomic weight sama dengan 1 . five (1) (12) =18g.
Equal weight: is definitely the molecular fat divided by number of reacting units
a- for stomach acids: the number of responding units is definitely the number of hydrogen ions that will furnish.
eq. wt HCl =M. wt/1
eq. wt H2SO4 =M. wt/2
eq. wt CH3COOH = Meters. wt/1
For H3PO4: the eq. wt depends on the effect
H3PO4 в‡” H++H2PO4-
frequency. wt: M. wt/1
2H+ + HPO24-
eq. wt: M. wt/2
frequency. wt: Meters. wt/3
For bases: the number of responding units is definitely the hydrogen ions that
is going to react with it:
KOH + H+ в†’ K++H2O
frequency. wt sama dengan Mwt
Ba(OH) 2 & 2H+в†’Ba2++2H2O
eq. wt = M. wt
Fe2O3 & 6H+ в†’ 2Fe3+ + 3H2O
c- For sodium ex: --
eq. wt = Mwt/6
Na2CO3 & HCl в†’
NaHCO3 + NaCl
eq. wt sama dengan M. wt
Na2CO3 + 2HCl в†’
H2CO3 + 2NaCl
frequency. wt sama dengan M. wt
d- For Oxidation вЂ“ reduction reaction
The number of reacting units is founded on the number of
electrons that the oxidizing or minimizing agent is going to take on or supply. It can be computed as well as the change in oxidation
Case in point:
MnO4- + 8H+ & 5e- в†”
Mn2+ + 4H2O reacting = 5units
MnO4- & e- в†”
MnO42reacting = 1units
IO3 + 6H + 4e I & 3H2O
sama dengan 4 models
e- Intended for reactions regarding formation of any precipitate or perhaps
There is no exchange of re-acting unit, nevertheless a combination of a metal ion with the reactant. The fee of the metallic ion is usually taken as the reacting product, and the equivalent weight can be equal to the atomic excess weight divided by charge of complexing agent is its molecular pounds divided by the number of steel ions which each gopher of the agent react. Case: AgNO3 в†’Ag+ + NO3-
eq. wt = Mwt of Aktiengesellschaft NO3
HgCl2в†” Hg2+ +2Cl-
eq. wt = .5 Mwt HgCl2
Examples: Calculate the equivalent fat of the next substances: a) NH3, b) H2C2O4 (in reaction with NaOH), c) KMnO4 (Mn is reduced to Mn2+) and d) Na3 PO4 (in precipitating Ag3 PO4-).
a) eq. wt of NH3=
b) eq. wt of H2C2O4 =
c) MnO4- + 8H + 5e
Mn 2+ + 4H2O
No . of electrons sama dengan 5 or perhaps oxidation point out of Meters is changed from +7 to +2 Eq. wt of KMnO4 =
d) Na3PO4 + 3Ag+