STIOCHIOMETRY Single answer type questions: 1. SO - + S - + I (Calculated amount) X + I -1. Then X in this reaction is a) SO - b) IO -1 c) SO - d) IO -1. A certain quantity of Ammonium chloride is boiled with 100 ml of 0.8 N NaOH till no further action occurs. Excess of NaOH required 0 ml of 0.7 N sulphuric acid to neutralise if. How much Ammonium chloride was used? (A) 0 g (B) g (C).67 g (D) 1 g. 0.66g of HPO will require X ml of 0.1 M NaOH for complete neutralisation. Then x = --- (A) 100 ml (B) 00 ml (C) 00 ml (D) 00 ml. In the preparation of iron from haematite ()Fe O by the reaction with carbon FeO C Fe CO How much 80% pure iron could be produced from 10kg of 90% pure FeO? a) 9. kg b) 60.8kg c) 116.66kg d) 10kg. Equivalent weight of HPO when it disproportinates in to PH and HPO (Mol weight = M) a) M b) M/ c) M/ d) M/ 6. moles of NH loses 16 moles of electrons is being converted to a new compound X. Assuming that all the N appears in the new compound. What is the oxidation state of N in X. a) 1 b) c) + d) + 7. A 10ml of solution of I is divided into two unequal parts. Part I reacts with hypo solution in acidic medium where 1ml of 0.M hypo was consumed. Part was added to 100ml of 0.M hot and conc. NaOH solution. Residual base required 10ml of 0.M H SO solution for complete neutralization. What was the initial concentration of (A) 0.08 M (B) 0.1 M (C) 0.M (D) 0.0M 8. 1000 ml of tap water containing Ca(HCO ) was titrated with N/0 HCl with methyl orange as indicator. If 00 ml of HCl were required, calculate temporary hardness as parts of CaCO 6 per 10 parts of water. (A) 10 ppm (B) 00 ppm (C) 0 ppm (D) 600 ppm I. 9. How many ml of 0. M aluminium permanganate solution will be needed to oxidize completely a 0 ml 0. M solution of ferrous oxalate in dil. HSO medium? (A) 0 (B)0 (C)0 (D)1 Page No - 1 -
0. When BrO ions reacts with Br in acid medium, Br is liberated. The equivalent weight of this reaction is (A) /8M (B) /M (C) / M (D) /6 M 1. A.0cm solution of HO liberates 0.08 g of I from an acidified KI solution. The strength of HO solution in terms of volume strength at STP is (A). vol (B) 8.96 vol (C) 1.1 vol (D).8 vol. A sample of pure KHCO. H CO.H O (three replaceable hydrogen) requires.6 mol of NaOH for titration. How many moles of KMnO will the same sample react with? (A) 1. (B). (C). (D).. A 0.6 g sample of copper ore is dissolved in an acid, and the Cu + of it is treated with excess of KI. The liberated I requires 10 ml of 0.1 M hypo solution for titration. What is % of copper by mass in the ore? (At. wt. of copper = 6.) (A) 1% (B) % (C) 10% (D) %. A mixture containing 0.0 mole of KCr O7 and 0.0 mole of KMnO was treated with excess of KI in acidic medium. The liberated iodine required 1.0 L of NaSO solution for titration. Concentration of NaSO solution was : 1 a) 0.0 mol L 1 b) 0.0 mol L 1 c) 0. mol L d) 0.0 mol L 1. The number of moles of KMnO that will be needed to react completely with one mole of ferrous oxalate in acidic solution is a) b) c) d) 1 6. 1 mole of equimolar mixture of ferric oxalate and ferrous oxalate will require x mole of KMnO in acidic medium for complete oxidation, x is a) 0.6 mole b) 0.9 mole c) 0. mole d) 1.8 mole 7. moles of a mixture Mohr s salt and Fe(SO) requires 00 ml of 1M KCrO7 for complete oxidation in acidic medium. The mole % of the Mohr s salt in the mixture is a) 10 b) 0 c) 0 d) 60 8. 1 grams of a calcium carbonate sample with non volatile impurities, on complete decomposition left 7.6 grams of residue. What is the percentage of impurities in the sample? A) 16.6 % B). % C) 1. % D). % 9. To a 0 ml of HO solution, excess of acidified solution of KI was added. The liberated I required 00 ml of 0. M NaSO for complete reaction. How much of it (in ml) are required to oxidize.g of HS gas? (A) 0 ml (B) 100 ml (C) 00 ml (D) 1 ml Page No - -
0. A solution contains NaCO and NaHCO. 10 ml of the solution requires. ml of 0.1M HSO for neutralisation using phenolphthalein as an indicator. Methyl orange is added when further. ml of 0. M H SO is required. The amount of NaHCOin one litre of the solution is A).1g B) 8. g C). g D). g Page No - -
Single Answers STIOCHIOMETRY KEY SHEET 1 C C A A D 6 C 7 B 8 B 9 D 0 C 1 D A C A A 6 B 7 D 8 A 9 B 0 D STIOCHIOMETRY SOLUTIONS Single solutions 1. It is known as Spring s reaction.. Let the volume of excess of 0.8 N NaOH after the reaction with ml. V ml of 0.8 N NaOH 0 ml of 0.7N H SO V 0.8 0 0.7 V 7.ml Volume of 0.8 N NaOH consumed by NHCl =100-7. =6. ml m. eq of NaOH consumed by NHCl = m. eq of NH Cl used. w 0.86. 1000. W =.67g. Conceptual. NaSO + NaS + I (calculated) Na SO + NaI Fe O C Fe CO 101000 90 Number of moles of FeO = 160 100 101000 90 6 Mass of 80% pure iron produced 160 100 0.8 = 900 gm = 9. kg NH Cl be V. M M E Page No - -
6. Each nitrogen uses electrons 7. 8. B 9. I Na S O NaI Na S O 6 Millimoles of Na S O consumed = 6 Millimoles of I consumed = I 6NaOH NaI NaIO H O 0 6 Millimole of I reacts with NaOH 1 Total millimole of I consumed in the reaction = 1 Initial concentration of 7 Al(Mn O) Mn n-factor = = 1 Fe C O Fe CO n-factor = V1n1M1 = VnM V1 1 0. = 0 0. V1 = 1 Ml 1 I 0.1M 10 0. BrO 1H 10Br 6Br 6H O 10 moles of t req. for formation of 6moles of Br 10 mol. Wt M n factor of BR ; EqWt. M 6 n / 1. meq H O meq I w /171000 0.08 / / 1000 w 0.068 g g of H O gives 11. lit of O 11. 0.068 0.068g. ml of O cc of HO solution gives =. ml of O. 1cc gives =..8 vol. KHC O. H C O.H O has three replaceable H H 1 NaOH 1.6NaOH.6.6 mol of salt 1. mol H 1 mol of salt has = mol of CO 1. mol of salt has =.08 mol of C O MnO Mn 10 CO H CO Page No - -
mol of C O mol MnO.08 mol of. (C) C O.08 1. mol MnO Meq of Cu + = Meq of I W Cu 6. 1 1000 Weight of Cu + = 10 0.1 = 1 (Cu e Cu) 0.06; % of Cu + in the sample 0.06 = 100 10% 0.6. eq. wt. of molar mass KCrO 7 6 Eq. wt. of Molar mass KMnO Eq. of NaSO = Eq. of I liberated = eq. of KMnO + eq. of KCrO 7. N 1 0.0 0.0 6 N 0. (or) M 0. MnO oxides both FeC O Fe C O Fe and Fe C O Fe CO e MnO e Mn CO FeCO MnO (or) 1FeCO MnO (or) 6. 7. Fe C O Vs MnO Fe (1) () CO Mn n factor 6 mole ratio = 6 0.? = 0.6 Fe C O Vs MnO Fe CO Mn n factor mole ratio = 0.? = 0. Total moles required is 0.9 Cr O 7 6Fe (Mohr s salt)+ 1 6 7 H Cr Fe H O Equiv. of Fe + (= moles of Mohr s salt) = Equiv. of K Cr O 7 0010 61.0 Page No - 6 -
Hence, mole precent of Mohr s salt = 100 60 8. Mass of sample = 1 gms Mass of residue = 7.68 gms (includes impurities) Mass of CO released = 1-7.6 =. gms gm CO 100 gm CaCO. gm CO 10 gm CaCO Mass of impurities = 1-10= gms. % impurities 100 1 = 16.6 % 9. Meq of HO = Meq of I = Meq of NaSO 0 NHO 00 0. N =. M 1 0. HO H S H O H O S moles of HS. 1 10 moles of HO = 1 10 M VinL = 1 10 volume in ml = 100 ml No. meq No.of meq. (formed from ) No.of meq 10 ml of solution has