Stoichometry part2

B,Mole-ratio method

It is the ratio between the number of moles if any substance is given reaction.

#In this method the given mass is converted into mole

-the number of mole for the required substance

Example what mass of water is required when 100g of calcium oxide react with water to produce calcium hydroxide? (atomic mass Ca-40,0-16, H-1)

Cao + H2O---> Ca (OH)2

MOLe of Cao-given mass/molar mass

n Cao=100g/56g/mol
n CaO=1.79mol

(1.79mol) CaO (1mol) + (x) H2O (1mol) --> Ca(OH)2

1.79mol/1mol=x/4mol

X=1.9 mol1 mol)/1mol

X=1,7mol

2. VOLUME VOLUME RELATIONSHIP

#At standard temperature pressure (STP)

1mol=22.4L=1atm =25°c

The relation b/n volume of gas and its number of molecule explained by AVOGADRO'S LAW

Avogadro's law-state that" Under the same condition of the temperature and pressure equal volume of all gas contain the same number of molecules and vice versa
V~n

Example-How many liters of ammonia are produced at STP if 501 of hydrogen reacted with enough nitroge

(22.4L) 3H2(50L) + N2-> (224)2NH3(x)

501/67.21-X/44.8)

X=50-44.8/67.2
X=33,33 L of ammonia

3, MASS -VOLUME RELATIONSHIP

-In this problem, either the mass og one substance is given the volume of the other required or the volume of one substance is given and the mass of the other one required

Example-How many gram of calcium carbonate are decomposed to produced 11.21 of CO2 at STP

(X) CaCo3 (100g ---> CaO (11.2L) CO2 (22.4L)

X/100g=11.2L/22.4L

X=11.2*100/22.4

X-50g of CaCO3