SSLC CHEMISTRY UNIT 2 MOLE CONCEPT - WORK SHEETS WORK SHEET 1

1 SSLC CHEMISTRY UNIT 2 MOLE CONCEPT - WORK SHEETS WORK SHEET 1 1 GAM atoms Mass in grams equal to its Atomic mass Element and GAM Number of Atoms Mass in grams 1 GAM Hydrogen atoms 1 g 1 GAM Helium atoms 4 g 1 GAM Oxygen atoms 16 g 1 GAM Chlorine atoms 35.5 g 2 GAM Chlorine 2 x atoms 2 x 35.5g 71 g 3 GAM Chlorine 3 x atoms 3 x 35.5 106.5 g 2 GAM Hydrogen 3 GAM Oxygen 1 GAM Hydrogen GAM Nitrogen atoms 4 x atoms 92 grams of Sodium

2 WORK SHEET 2 Number of GAM Mass in grams / Gram Atomic Mass of the element Number of Atoms Number of GAM x N A Find the GAM and number of atoms in each of the following sample of elements (Atomic Mass H 1, He 4, O 16, C 12, N 14, Na 23) Sample GAM Number of Atoms 40 g Hydrogen 40 40 x atoms 40 g Helium 10 10 x atoms 40 g Oxygen 2.5 2.5 x atoms 120 g Carbon 10 10 x atoms 140 g Nitrogen 6 g Carbon 460 g Sodium 7 g Nitrogen

3 WORK SHEET 3 Number of particles Hydrogen atoms (H) Mass 1 g Hydrogen Molecules (H 2 ) 2 g Oxygen atoms (O) 16 g Oxygen Molecule (O 2 ) 32g Carbon dioxide (CO 2 ) Water Molecules (H 2 O) Nitrogen atoms (N) 44 g 18 g Nitrogen Molecules (N 2 ) Ammonia (NH 3 ) Sodium hydroxide (NaOH)

4 WORK SHEET 4 GRAM MOLECULAR MASS Number of Gram Molecular Mass (Gram Molecules) Mass in Grams / Gram Molecular Mass of the substance Substance Gram Molecular Mass (Calculated) Number of GMM Number of Molecules 90 g Water (H 2 O) 1x 2 + 16 x 1 2+ 16 18 90g/18g 5 5 x 85 g Ammonia(NH 3 ) 14x 1 + 1 x 3 14+ 3 17 85g/17g 5 5 x 90 g Glucose (C 6 H 12 O 6 ) 88g Carbondioxide(CO 2) 50 g Hydrogen (H 2 ) 12x 6 + 1 x 12 + 16 x 6 72+1 2+ 96 180 WORK SHEET 5 90g/180g 0.5 0.5 x 1 Mol of any substance contains elementary particles. Eg 1 mol of Hydrogen atoms 1 g atoms of Hydrogen. 1 mol of Hydrogen molecules 2 g molecules of Hydrogen. 1 Mole atom 1 GAM 1 Mole of molecules 1GMM Substance Mass Number of Particles Number of Atoms 1 mole of oxygen atoms (O) 16 g atoms. 1 mole of oxygen Molecules (O 2 ) 32 g molecules. 2 x 1 mole of ozone Molecules (O 3 ) 48 g molecules. 3 x 1 mole of Helium atoms (He) 4 g atoms. 1 mole of Helium Molecules(He) 4 g molecules. 1 mole of Water (H 2 O) 18 g molecules. 3 x 1 mole of Carbon dioxide (CO 2 ) 1 mole of NaOH 1 mole of Ammonia (NH 3 ) 1 mole of Glucose (C 6 H 12 O 6 )

5 WORK SHEET 6 Number of moles - from the number of particles Number of moles Number of Particles / Avogadro Number. Find the number of moles of the following. Number of Particles Number of Moles 10000 molecules of Water 10000 / 100000 molecules of CO 2 100000 / 100000 molecules of H 2 100000 / molecules of Glucose / 12.044 x 10 23 molecules of SO 2 _ 3.011 x 10 23 molecules of NH 3 _ WORK SHEET 7 Number of moles of atoms - from mass Number of moles of atoms Mass in grams / Gram atomic mass Find the number of mole atoms of the following. Mass in grams Number of Mole atoms 16 g of oxygen 16g / 16 g 1 32 g of oxygen 32g / 16 g 2 160 g of oxygen 160g / 16 g 10 14 g of nitrogen _ 140 g of nitrogen _ 7 g of nitrogen _ 700 g of nitrogen _

6 WORK SHEET 8 Number of moles of molecules - from mass Number of moles of molecules Mass in grams / Gram molecular mass Mass in grams Find the number of moles of the following. Number of Moles 32 g of oxygen 32g / 32 g 1 320 g of oxygen 320g / 32 g 10 16 g of oxygen 16g / 32 g 0.5 14 g of nitrogen _ 140 g of nitrogen _ 7 g of nitrogen _ 700 g of nitrogen _ 220 g of CO 2 _ WORK SHEET 9 Number of particles Number of moles x N A Mass of the substance Number of moles x GAM (for atoms) Mass of the substance Number of moles x GMM (for molecules) Number of Moles Number of Molecules 4 moles of Water 4 x N A 5 moles of nitrogen 10 moles of CO 2 _ Number of Moles Mass 20 moles of Oxygen atoms 20 x GAM 20 x 16g 320g 20 moles of Oxygen molecules 20 x GMM 20 x 32g 640g 25 moles of Carbon atoms _ 30 moles of Hydrogen molecules _ 30 moles of Hydrogen atoms _ 40 moles of Chlorine molecules _ 40 moles of Chlorine atoms _

7 WORK SHEET 10 Number of molecules and number of atoms - from number of moles Number of moles Mass in grams / Gram molecular mass Number of atoms (from number of molecules) Total number of atoms in a molecule x Number of molecules Mass in grams Number of Moles Number of Molecules Number of atoms 32 g of oxygen (O 2 ) 32g / 32 g 1 1x 1x 2 x 16 g of oxygen (O 2 ) 16g / 32 g 0.5 0.5x 0.5 x2 x 960 g of Ozone (O 3 ) 960g / 48 g 20 20x 20 x3 x 710gof Chlorine (Cl 2 ) _ 90g of Glucose (C 6H 12O 6) _ 46 g of Sodium (Na) _ 220 g of CO 2 _ WORK SHEET 11 Mass of atoms GAM Mass of one atom GAM / N A Mass of one molecule GMM / N A Number of Particle Equation Mass 1 molecules of Water GMM / N A 18g/ N A 1000000 molecules of Water Number x (GMM/N A) 1000000 x (18g/ N A ) One atom of nitrogen GAM / N A 14g / N A One molecule of nitrogen One molecule of Sulphuric acid (H 2 SO 4 )

8 WORK SHEET 12 Problems related to STP STP means Standard Temperature and Pressure Standard Temperature 0 0 C (273 Kelvin) Standard Pressure 1 atmosphere (1 atm) Number of moles at STP Volume of the gas at STP in litres / 22.4 litres. One mole of every gas at STP occupies 22.4 litres. Volume of the gas Number of moles Number of molecules 22.4 L of CO 2 22.4L/22.4L 1 1 x 44.8 L of CO 2 44.8L/22.4L 2 2x 11.2L of NH 3 11.2L/22.4L 0.5 0.5x 22400 ml of SO 2 (22400/1000)L / 22.4L 1 1 x 112 L of CO 67.2 L of NH3 WORK SHEET 13 Problems related to Balanced Chemical Equations N 2 + 3H 2 2 NH 3 This equation has the following meanings too * 1 mol of N 2 + 3 moles of H 2 2 moles of NH 3 28 g of N 2 + 3 x 2g of H 2 2 x 17 g NH 3 * 28 g of N 2 + 6g of H 2 34 g NH 3 @STP * 22.4 L of N 2 + 3 x 22.4 L of H 2 2 x 22.4L NH * 22.4 L of N 2 + 67.2L of H 2 44.8L of NH 3

9 1. Find the mass of NH 3 formed from 140 grams of N 2. * Mass of NH 3 formed from 28 grams of N 2 34g * Mass of NH 3 formed from 1 gram of N 2 34g/28 * Mass of NH 3 formed from 140 grams of N 2 (34g/28 ) x 140 170 g 2. Find the mass of NH 3 formed from 7 grams of N 2. * Mass of NH 3 formed from grams of N 2 _ g * Mass of NH 3 formed from 1 gram of N 2 _ g * Mass of NH 3 formed from 7 grams of N 2 _ g 3. Find the mass of Hydrogen required to react with 500 g of N 2 *Mass of Hydrogen required to react with 28g of N 2 6 g *Mass of Hydrogen required to react with 1g of N 2 6/28 g *Mass of Hydrogen required to react with 500g of N 2 (6/28 g) x 500 107.14 g 4. Find the mass of Hydrogen required to react with 560 g of N 2 *Mass of Hydrogen required to react with g of N 2 g *Mass of Hydrogen required to react with 1g of N 2 g *Mass of Hydrogen required to react with 560g of N 2 g 5. What is the mass of N 2 needed to get 1000 L of NH 3. * Mass of N 2 needed to get 44.8 L of NH 3 28g * Mass of N 2 needed to get 1 L of NH 3 28g /44.8 * Mass of N 2 needed to get 1000 L of NH 3 (28g /44.8 ) x 1000 625 g 6. What is the mass of N 2 needed to get 500 ml of NH 3 * Mass of N 2 needed to get _L of NH 3 --- g * Mass of N 2 needed to get 1 L of NH 3... g * Mass of N 2 needed to get L of NH 3...g

10 WORK SHEET 14 Number of moles of solutions Molarity Number of moles of solute / Volume of the solution in litres. That is, Molarity n/v Preparation of 1 litre 1 molar solution of any solute. Take 1 GMM (Equal to its molecular mass )of the solute. Add a little water to dissolve it. Add enough water till the total volume of the solution becomes 1 litre. Number of moles of Solute (n) Total volume of the solution (V) Molar concentration ( Molarity) (n/v) 1 mole 1 L 1 M 2 moles 2 L 1 M 0.5 mole 0.5 L 1 M 0.5 mole 1 L 0.5 M 0.5 mole 2L 0.25 M 2 moles 10 L _ 1 mole 0.5 L _

11 1.How will you prepare one molar solution (1 Litre) of NaCl. Answer: - The molecular mass of NaCl is 58.5. Take 58.5 grams of NaCl. Add a little water. Dissolve the solute. Add more water till the volume of the solution becomes 1 litre. 2.How will you prepare one molar solution (1 Litre) of NaOH. Answer: - The molecular mass of NaOH is 40. Take 40 grams of NaOH. Add a little water. Dissolve the solute. Add more water till the volume of the solution becomes 1 litre. 3.How will you prepare 0.5 molar solution (1 Litre) of NaCl. Answer: - The molecular mass of NaCl is 58.5. Take 58.5 x 0.5 29.25 grams of NaCl. Add a little water. Dissolve the solute. Add more water till the volume of the solution becomes 1 litre. 4. How will you prepare two molar solution (1 Litre) of NaOH. Answer: - The molecular mass of NaOH is 40. Take 40 x 2 80 grams of NaOH. Add a little water. Dissolve the solute. Add more water till the volume of the solution becomes 1 litre. If volume of the solution is doubled by adding the solvent, the molarity of the solution reduces to half 5. How will you prepare a 0.25 molar one litre solution of NaCl from 1 Molar 1 litre NaCl solution. Answer:- Add 1 litre of water to it. It becomes a 0.5 molar solution. (Now the volume of the solution becomes 2 litres ) Add 2 litres of water to it. (Now the total volume of the solution reaches 4 litres.) W a will get a 0.25 molar solution.

12 Equations - Capsule Numerical Problems are related to the following areas 1 2 3 4 5 Atoms Molecules STP (Only for gases) Chemical equations * Number of Mole atoms Mass in grams /Gram Atomic Mass * Number of atoms Number of Mole atoms x N A * Number of Moles Mass in grams / Gram Molecular Mass * Number of Molecules Number of Moles x N A * Number of atoms Total number of atoms in a molecule x Number of molecules STP Means Standard Temperature (O 0 C or 273 K) and Pressure (1 atm) * Number of moles at STP Volume of the gas in litres at STP / 22.4 litres ml (cm 3 )/1000 Litres (Solve logically) Molar Solutions * Molarity Number of moles of solute / Volume of solution in litres ml (cm 3 )/ Litres