SIMPLE CALCULATIONS
When PbO2 is heated it decomposes into PbO and O2.
2PbO2  2PbO + O2
1. How many moles of PbO2 is required to produce 8.96L O2 at STP
2. What is the number of moles of PbO2 is required to produce 12.8g O2?
When propyne gas, C3H4, burns in oxygen, carbondioxide and water are produced.
C3H4 + 4O2  3CO2 + 2H2O (QUESTION 3,4)
3. How many grams of water are produced from 8g C 3H4?
4. How many liters of C3H4 at STP must be burned to produce 9g H2O?
Iron reacts with steam according to the equation:
3Fe (s) + 4H2O  Fe3O4(s) + 4H2 (QUESTION 5)
5. How many grams of Fe3O4 will be formed by the complete reaction of 1.68g of iron?
Nitrogen monoxide reacts with oxygen to form nitrogen dioxide.
2NO(g) + O2(g)  2NO2(g) (QUESTION 6,7)
6. What volume of nitrogen dioxide will be obtained from 120g of nitrogen monoxide?
7. What is the total volume of two reactants?
8. How many moles of water are produced when 84 g of iron are consumed according to the following reaction ?
3Fe + 8HNO3  3Fe(NO3)2 + 2NO + 4H2O
LIMITING-EXCESS REAGENT PROBLEMS
Given the reaction:
2NH3(g)+3Cl2(g)N2(g)+6HCl(g)
Determine the amount in moles of the excess reactant in each of the followings and what is the number of moles of HCl
in each.(QUESTION 8,9,10)
9. 1 mol NH3 and 1.5 mol Cl2
10.
10.2g of NH3 and 134.9g of Cl2
11.
1.12L of NH3 at STP and 4.48L of Cl2 at STP
12. How many grams of beryllium fluoride, BeF2, can be prepared from 18g of beryllium and 19g of fluorine?
13. 18 g of carbon and 8 g of oxygen are reacted to form carbon dioxide. Which element and how many grams
remain behind ?
14.
What mass of MoF5 is obtained from 42g of MoF6 and 66g of Mo(CO)6 by the reaction:
5MoF6+Mo(CO)66MoF5+6CO
15.
How many grams of N2F4 can be prepared from 17g of NH3 and 38g of F2?
2NH3+5F2N2F4+6HF
16.
Equal number of moles of iron and oxygen are reacted to form 32g of iron (III) oxide. Which element and how
many grams remain unreacted?
PERCENT YIELD PROBLEMS
CaC2+ 3H2O + H2  Ca(OH)2 + C2H5OH
15.How many grams of C2H5OH that is 93% pure can be produced from 128g CaC 2?
17.
How many liters of O2 at STP will be formed from 40.8g of KClO3 that is 40% pure?
18.
When 20g of iron is reacted with oxygen, 20g of iron(III) oxide is formed. What percent of iron is reacted with
oxygen?
DETERMINATION OF UNKNOWN SUBSTANCES
19.
10.8g of Al combines with 32g of X2O3 to give Al2O3 and 2X. What is the atomic weight of X?
20.
2.24L of XO2 at STP is produced from 3.8g of CX2 in the equation:
CX2(l)+3O2CO2(g)+2XO2(g)
What is the atomic weight of X?
Determine the empirical formula of the compounds made of only C and H in each of the followings questions(19,20,21)
21.
The combustion of 0.4mol of the compound produces 0.8mol of CO2 and 1.2mol of H2O.
22.
The combustion of the compound produces 33g of CO2 and 18g of H2O.
23.
The mass of H2O is 0.45 times the mass of CO2 in the combustion products of the compound.
24.
The complete combustion of a 18.5g of compound consisting of C, H and O produced 44g of CO 2 and 22.5g of
H2O. What is the empirircal formula of the compound?
25.
When a quantity of compound containing C, H and S is completely burned in oxygen, 88g of CO 2, 18g of H2O
and 32g of SO2 are produced. Calculate the empirical formula of the compound.
26. 60 g of C-H-O compound contains 4 g of hydrogen and 32 g of oxygen.What is its empirical formula ?
MIXTURE PROBLEMS
27. 16 g mixture containing FeO and Fe powder reacts with hydrochloric acid and 2,24 L of H2 produce
at STP. What is the mass of FeO in the mixture?
28. 40 g of an alloy made from Al and Zn is reacted with sufficient amount of HCl and 38,1L of H 2
at STP are produced. What is the mass of Al in the mixture?
29. When a 50 g alloy of copper and aluminum reacts with sufficient amount of hydrochloric acid, 22,4 L of
hydrogen at STP is produced. What is the mass of copper in the alloy ?
30. To burn 30 liters of a mixture of methane(CH 4) and propane(C3H8) gases , 90 liters of oxygen are needed at the
same conditions. Calculate the volume of methane in the mixture.
31. 10 g mixture of Zn-Cu is reacted with excess HCl and 2.24 L of hydrogen gas are produced at STP. What is the
mass of Cu in the mixture ?
32. When 41,2 g mixture of Na-Ca is reacted with water 22,4 L of hydrogen gas produce at STP. What is
the mass of calcium in the mixture ?
SOLUTIONS
33. Define the followings with examples
Solution - Solvent – Solute- Electrolyte-Non-electrolyte-Weak electrolyte
34. Explain fp depression and bp elevation with examples
35. What is saturated and unsaturated solution
36. Explain Factor effecting solubility
*Temperature *Pressure