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Online form 3 chemistry video lessons and lectures in Kenya

17 video lessons

• An organic compound J has the following percentage by mass, carbon, 64.86%, hydrogen, 13.51% and the rest oxygen. The relative molecular mass of the compound is 74.
  

  An organic compound J has the following percentage by mass, carbon, 64.86%, hydrogen, 13.51% and the rest oxygen. The relative molecular mass of the compound is 74. Work out the molecular formula of compound J. [C=12. H=1 O=16]

  
  Form 3, Chemistry: Mole Concept

  Date posted: March 5, 2019.

• 100cm³ of 2M nitric acid reacted with 12.5g of a carbonate of metal M. (MCO₃) according to the following equation
  

  100cm³ of 2M nitric acid reacted with 12.5g of a carbonate of metal M. (MCO₃) according to the following equation a).Calculate the number of moles of...

  
  Form 3, Chemistry: Mole Concept

  Date posted: March 5, 2019.

• 120cm³ of nitrogen gas diffuses through a membrane in forty seconds. How long will it take 240cm³ of carbon (IV) oxide to diffuse through the same membrane (C=12,N=14,O=16)
  

  120cm³ of nitrogen gas diffuses through a membrane in forty seconds. How long will it take 240cm³ of carbon (IV) oxide to diffuse through the same membrane (C=12,N=14,O=16)

  
  Form 3, Chemistry: Gas Laws

  Date posted: March 5, 2019.

• Fertilizers are added to the soil to improve crop yields. A farmer has a choice of two fertilizers, ammonium nitrate NH₄NO₃ or diammonium hydrogen phosphate (NH₄₎₂HPO₄)
  

  Fertilizers are added to the soil to improve crop yields. A farmer has a choice of two fertilizers, ammonium nitrate NH₄NO₃ or diammonium hydrogen phosphate (NH₄₎₂HPO₄.Show by calculation which of these fertilizers contains the greater percentage of...

  
  Form 3, Chemistry: Nitrogen and its Compounds

  Date posted: March 4, 2019.

• A fixed mass of a gas has a volume of 250cm³ at a temperature 27°C and 750mmHg pressure. Calculate the volume the gas would occupy at 42°C and 750mmHg pressure. (0°C = 273K)
  

  A fixed mass of a gas has a volume of 250cm³ at a temperature 27°C and 750mmHg pressure. Calculate the volume the gas would occupy at 42°C and 750mmHg pressure. (0°C = 273K)

  
  Form 3, Chemistry: Gas Laws

  Date posted: March 4, 2019.

• 30cm³ of hydrogen chloride gas diffuses through a porous pot in 20 seconds. How long would it take 42cm³ of sulphur(IV) oxide gas to diffuse through the same pot under the same conditions (H =1 Cl = 35.5 S = 32 O =16)
  

  30cm³ of hydrogen chloride gas diffuses through a porous pot in 20 seconds. How long would it take 42cm³ of sulphur(IV) oxide gas to diffuse through the same pot under the same conditions (H =1 Cl = 35.5 S = 32 O =16)

  
  Form 3, Chemistry: Gas Laws

  Date posted: February 26, 2019.

• Draw the structural formulae of the following compounds: a) 2, 3 – dibromobutane b) 2, 3, 4 – trimethyl pentene c) 4 – chloro – 5 – methylhex – 2 –yne
  

  Draw the structural formulae of the following compounds: a) 2, 3 – dibromobutane b) 2, 3, 4 – trimethyl pentene c) 4 – chloro – 5 – methylhex – 2 –yne

  
  Form 3, Chemistry: Organic Chemistry 1

  Date posted: February 26, 2019.

• 4.0g of magnesium carbonate have some impurity of magnesium sulphate were dissolved in 250cm³ of 1.0m HCL. 25cm³ of the resulting solution was found to require 28.8cm³ of 0.6M sodium hydroxide for complete neutralization.Calculate the number of moles of sodium hydroxide in 28.8cm³.
  

  4.0g of magnesium carbonate have some impurity of magnesium sulphate were dissolved in 250cm³ of 1.0m HCL. 25cm³ of the resulting solution was found to require 28.8cm³ of 0.6M sodium hydroxide for complete neutralization.Calculate the number of moles of sodium...

  
  Form 3, Chemistry: Mole Concept

  Date posted: February 26, 2019.

• Calculate the percentage nitrogen content in the following ammonium salts. i) Ammonium sulphate (NH₄₎₂SO₄ ii) Urea, (NH₂₎₂CO N= 14, H=1, S=32, O=16, C=12
  

  Calculate the percentage nitrogen content in the following ammonium salts. i) Ammonium sulphate (NH₄₎₂SO₄ ii) Urea, (NH₂₎₂CO N= 14, H=1, S=32, O=16, C=12

  
  Form 3, Chemistry: Nitrogen and its Compounds

  Date posted: February 26, 2019.

• Write an equation to show the effect of heat on: i) Potassium nitrate, KNO₃ ii) silver nitrate, AgNO₃
  

  Write an equation to show the effect of heat on: i) Potassium nitrate, KNO₃ ii) silver nitrate, AgNO₃

  
  Form 3, Chemistry: Nitrogen and its Compounds

  Date posted: February 26, 2019.

• Zinc metal and hydrochloric acid react according to the following equation: Zn_(s) + 2Hcl_(aq)= ZnCl_2(aq) + H_2(g)
  

  Zinc metal and hydrochloric acid react according to the following equation: Zn_(s) + 2Hcl_(aq) = ZnCl_2(aq) + H_2(g) 1.96g of zinc metal were reacted with 100cm³ of 0.2m hydrochloric Acid. a) Determine the reagent that was in excess. b)...

  
  Form 3, Chemistry: Mole Concept

  Date posted: February 26, 2019.

• An organic compound contains 24.24% carbon 4.04% hydrogen and the rest is chlorine a) Find its empirical formula. (C=12, H=1, Cl=35.5) b) Find its molecular formula if its R.M.M is 99.
  

  An organic compound contains 24.24% carbon 4.04% hydrogen and the rest is chlorine a) Find its empirical formula. (C=12, H=1, Cl=35.5) b) Find its molecular formula if its R.M.M is 99.

  
  Form 3, Chemistry: Mole Concept

  Date posted: February 26, 2019.

• Study the information in the table below and answer the questions that follow.
  

  Study the information in the table below and answer the questions that follow. i) Write the general formula of the hydrocarbons in the table. ii) Predict the relative...

  
  Form 3, Chemistry: Organic Chemistry 1

  Date posted: February 26, 2019.

• 6g of iron reacted with hydrogen chloride gas to form iron (II) chloride at S.T.P. Calculate the volume of the hydrogen chloride gas used. (Fe=56, molar gas volume at S.T.P=22.4dm³ )
  

  6g of iron reacted with hydrogen chloride gas to form iron (II) chloride at S.T.P. Calculate the volume of the hydrogen chloride gas used. (Fe=56, molar gas volume at S.T.P=22.4dm³ )

  
  Form 3, Chemistry: Mole Concept

  Date posted: February 26, 2019.

• When 27.8g of hydrated aluminium oxide, Al₂O₃.xH₂O, was heated to a constant mass, 20.6g of aluminium oxide was obtained. Determine the value of x (H=1, O=16, A=27)
  

  When 27.8g of hydrated aluminium oxide, Al₂O₃.xH₂O, was heated to a constant mass, 20.6g of aluminium oxide was obtained. Determine the value of x (H=1, O=16, A=27)

  
  Form 3, Chemistry: Mole Concept

  Date posted: February 26, 2019.

• During heating of a hydrated copper (II)sulphate crystals, the following readings were obtained: Mass of evaporating dish =300.0g, Mass of evaporating dish + hydrated salt = 305.0g, Mass of evaporating dish + anhydrous salt = 303.2g
  

  During heating of a hydrated copper (II)sulphate crystals, the following readings were obtained: Mass of evaporating dish =300.0g, Mass of evaporating dish + hydrated salt = 305.0g, Mass of evaporating dish + anhydrous salt = 303.2g Calculate the number of water of crystallization molecules in...

  
  Form 3, Chemistry: Mole Concept

  Date posted: February 26, 2019.

• 1.60g of an oxide of Magnesium contain 0.84g by mass of Magnesium. Determine its empirical formula(Mg = 24.0, 16.0)
  

  1.60g of an oxide of Magnesium contain 0.84g by mass of Magnesium. Determine its empirical formula(Mg = 24.0, 16.0)

  
  Form 3, Chemistry: Mole Concept

  Date posted: February 25, 2019.