# Numerical Problems on Mole Concept Class XI

Dear Students,

Today we will present you with the numerical problems on the mole concept. This concept is very useful to understand chemical reactions from a quantitative perspective.

Mole is generally a representation quantity of amount taken in the chemical reaction therefore, students need to understand in depth this topic.

## Mole Concept of Class XI

01. A chemist has a jar containing 388.2 g of iron filings. How many moles of iron does the jar contain?

02. Calculate the number of moles in each of the following masses:

a. 64.1 g of aluminium

b. 28.1 g of silicon

c. 0.255 g of sulphur

d. 850.5 g of zinc

03. A student needs 0.366 mol of zinc for a reaction. What mass of zinc in grams should the student obtain?

04. Calculate the mass of each of the following amounts:

a. 1.22 mol sodium

b. 13.5 mol copper

c. 0.275 mol mercury

d. 9.37 x 10-3 mol magnesium

05. How many moles of lithium are there in 1.204 x 1024 lithium atoms?

06. Calculate the amount in moles in each of the following quantities:

a. 3.01 x 1023 atoms of lithium

b. 8.08 x 1022 atoms of sodium

c. 5 700 000 000 atoms of oxygen

07. How many boron atoms are there in 2.00 g of boron?

08. Calculate the number of atoms in each of the following masses:

a. 54.0 g of aluminum

b. 69.45 g of nitrogen

c. 0.697 g of boron

09. How many moles of carbon dioxide are in 66.0 g of dry ice, which is solid CO2?

10. Calculate the number of moles in each of the following masses:

a. 3.00 g of boron tribromide, BBr3

b. 0.472 g of sodium fluoride, NaF

c. 7.50 x 102 g of methanol, CH3OH

11. Determine the mass of each of the following amounts:

a. 1.366 mol of NH3

b. 0.120 mol of glucose, C6H12O6

c. 6.94 mol barium chloride, BaCl2

12. Determine the number of molecules in 0.0500 mol of hexane, C6H13.

13. Calculate the number of molecules in each of the following amounts:

a. 4.99 mol of methane, CH4

b. 0.005 20 mol of nitrogen gas, N2

c. 1.05 mol of PCl3

14. An adultтАЩs bones weigh about 11 kg, and 50% of this mass is calcium phosphate, Ca3(PO4)2. What is the mass of phosphorous in the bones of an average adult.

15. Calculate the number of particles in- (i) 8 g of O2 molecules (ii) 2.5 mol of calcium atoms

16. What is the mass of 2.5 mol of Methane?

17. Find the mass of one molecule of water?

18. Calculate the number of water molecules and number of oxygen and hydrogen atoms in a drop of water containing 0.03 mol of water.

19. How many molecules of water and oxygen atoms are present in 0.9g of water?

20. Calculate mass of Nitrogen (N2) which contains same number of molecules as are present in 4.4 grams of Carbondi-oxide (CO2).

21. Atomic mass of gold is 197 u. How many moles of gold are present in an ornament containing 88.65 grams of gold?

22. A glass of water contains 5 mol of water. How many molecules of water are present?

23. How many atoms of Silver (Au = 108 g/mol) are present in a silver wire weighing 5.4 grams?

24. How many C atoms are there in a carbon rod weighing 8 g (C=12)

25. How many grams of copper (Cu = 64) contain 4.5 x 1023 atoms?

26. How many (i) molecules (ii) atoms are there in 35.5 g of gaseous chlorine Cl2?

27. How many ions are there in 13.5 g of copper (II) chloride, CuCl2?

28. How many moles of carbon dioxide molecules are present in 11 g of carbon dioxide, CO2?

29. What is the mass of 3 mole of carbon monoxide?

30. What mass of magnesium (Mg=24) would contain the same number of atoms as 4 g of carbon. (C=12)

31. Calculate the mass of (i) 1 atom of magnesium. (ii) 5 molecule of ethane.

32. Calculate the mole of each element present in 18.4 g of iron (III) sulphate.

33. Taking Avogadro’s constant equal to 6 x 1023, find the number of molecules in (a) 3.4 g of ammonia, NH3 (b) 7.7 g of carbon tetrachloride CCl4

34. If 0.5 mole of a hydrated salt X.nH2O contains 63 g of water of crystallization, find the value of n.

35. Chlorine exist in two isotopic forms; 35Cl and 37Cl in percentage compositions of 75% and 25% respectively. Calculate the relative atomic mass of chlorine.

36. A sample of ordinary neon is found to consist of 20Ne, 21Ne and 22Ne in percentage 20Ne = 90.22%, 21Ne = 0.26% and 22Ne = 8.82%. Calculate the actual atomic weight of neon.

37. Copper has a relative atomic mass of 63.55 and consists of two isotopes of mass number 63 and 65. Calculate the percentage composition of the isotopes.

38. The two isotopes of hydrogen having mass number 1 and 2 have atomic weight equal to 1.007825 and 2.01373 as determined by mass spectrograph. These isotopes are present in ordinary hydrogen in ratio of 6400 to 1. Determine the mean-atomic weight of hydrogen atoms.

39. Calculate number of atoms in the following samples of substances

0g of iodine

0g of magnesium

0g of chlorine

0g of hydrogen

40. Find the molar mass of the following:

a. CaCO3

b. manganese(IV) oxide

c. calcium phosphate

d. zinc(II) chloride nonahydrate

41. How many moles are there in a 124 g sample of C8H18?

42. How many atoms are there in 12 molecules of cobalt(II) sulphate pentahydrate?

43. What is the mass of 5.99 mol of C6H2Cl4?

44. How many molecules are there in 3.2 mol of sodium chloride?

45. How many moles in 4.113 x 1088 molecules of nitrogen trifluoride (NF3)?

46. How many moles in 1200 mL of oxygen gas at STP?

47. What is the percentage composition of iron in FeCl3?

48. What is the percentage composition of potassium in K3PO4?

49. What is the mass of 5 million atoms of copper?

50. What is the mass of 400.0 mL of fluorine gas at STP?

51. 0 mL of butane gas at STP contains how many molecules?

52. How many molecules in 3 kg of potassium iodide?

53. What is the volume of 4.92 g of hydrogen gas at STP?

54. What is the volume of 3.66 x 1032 molecules of fluorine gas at STP?

55. What is the percentage composition of calcium chloride?

All the best Students

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