Work Sheet Class 11 MidTerm 2015

Chapter 1- Some Basic Concepts of Chemistry

  1. An element X forms two oxides containing 77.47 and 69.62 percent of X respectively. What’s the formula of second oxide?
  2. Illustrate the law of reciprocal proportions from the following results:
  3. In ammonia, N=82.35% , H= 17.65%.
  4. In water, O=88.9% , H= 11.1%.
  5. In nitrogen trioxide, N=36.85% , O= 63.15%.
  1. Illustrate the law of reciprocal proportions from the following results:

In phosphorous chloride, P=22.57% , Cl= 77.43%.

In phosphine, , P=91.18% , H= 8.82%.

In hydrogen chloride, H=2.77% , Cl= 97.23%.

  1. Phosphorous (at mass 31) combines with hydrogen.(at mass 1) in the ratio of 3.1:0.3. In water, hydrogen and oxygen (at mass 16) combine in the ratio 0.2:1.6.

i) From the above data, calculate the mass ratio of phosphorous and oxygen in the oxide of phosphorous.

ii)What is the name of the law applied in calculating this ratio and state the law ? iii)What is the valency of phosphorous in an oxide where the mass ratio of phosphorous to oxygen is 3.1:4?

  1. When silver nitrate was heated with 5.08g of iron chloride 11.48g of silver chloride was formed. 6.51g of another iron chloride gave 17.22g of silver chloride on treatment with silver nitrate.

i. Show that these results illustrate the Law of Multiple Proportion.

ii. State low of reciprocal proportion.

  1. 0.16g of a dibasic acid required 25 ml of N/10 NaOH for complete neutralization. Calculate its molecular mass.
  1. 0.08 g of a diacid base required 7.5mL of N/5 HCl for complete neutralization. Calculate the molecular mass of the base?
  1. 0.105g of a volatile compound on treatment in a Victor Meyer’s apparatus displaced 40.5 ml air collected over water at 15oC and 746 mm of Hg pressure. Calculate the molecular weight of compound. (Aqueous tension at 15oC = 13.7 mm)
  1. What volume of oxygen is required at stp to effect the complete combustion of six litres of methane at 15oC and 740 mm of Hg?
  1. 24 grams of a solid element required 44.8 liters of oxygen at STP for its complete conversion into a gaseous oxide. The gaseous oxide occupies a volume of 44.8 liters at

STP. What is the weight of the gaseous product and its vapor density?

  1. A sample of sodium hydroxide weighing 0.38 grams is dissolved in water and the solution is made to 50 cm3 in a volumetric flask. What is the molarity of the resulting solution? How many moles of sodium hydroxide are contained in 27 cm3 of 0.15 molar solution?
  1. It has been found that 0.290g of an organic compound containing C,H and O on complete combustion yielded 0.66g of CO2 and 0.27g of H2O. the vapour density of the compound is found to be 29. Determine the molecular formula of the compound.
  2. 65.6 grams of solid calcium nitrate is heated and it undergoes thermal decomposition. find :

i. The volume of oxygen evolved at stp on heating 65.6 grams of calcium nitrate.

ii. The mass of calcium oxide formed at same time.

. iiiThe mass of calcium nitrate required to produce 5 moles of gaseous products.

ivThe mass of calcium nitrate required to produce 44.8 litres of nitrogen dioxide at stp.

14.An impure sample of table which weighed 6.5 g gave on treatment with excess silver nitrate solution to obtain 14.35 g of silver chloride. calculate the percentage purity of table salt.

15. Calculate the concentration of nitric acid in moles per litre in a sample which has a density of 1.41 g per ml nd the mass percent of nitric acid being 69%.