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Kathryn Hines
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1 SOLUTIONS Homogeeous mixture: Substaces which dissolve with each other thoroughly to form a uiform mixture is called homogeeous mixture. Eg: Water + Salt. Solutios: homogeeous mixture formed with two or more substaces is called as solutio. Compoets: Substaces preset i solutio are called as compoets. Solvet: compoet which is larger i quatity i a solutio is called solvet. Eg: Water i salt water. Solute: compoet which is less i quatity i a solutio is called solute. Eg: Salt i salt water queous Solutio: If the solvet i a solutio is water, the solutio is called as aqueous solutio. Types of Solutio: Solutio are divided ito usaturated, saturated ad super saturated solutios based o the solubility of the solute. Note: Super saturated solutio is more ustable. Solubility: The maximum amout of solute by weight i grams i 100 grams of solvet at costat temperature is called the solubility of that substace. Eg: Solubility of certai compouds at 30 C. S.NO. Compoud (Formula) Solubility - Grams (I 100 grams of water) 1 Ca KMO H 2 C 2 O 4.2H 2 O CuSO 4 2H 2 O NaCl gno Factors affectig solubility of substaces. (a) Nature of solute & solvet. (b) Temperature. Geerally polar substaces dissolve i polar solvets, but ot i a o-polar solvets. I the same maer o-polar substaces dissolve i o-polar solvets but ot i polar solvets. Eg (1): Copper Sulphate is a polar solute. Hece it dissolves i water which is also a polar solvet. ut the same copper sulphate does't dissolve i kerosee as kerosee is a o-polar solvet.

2 Eg (2): Naphthalee is a o-polar solute. Hece it dissolves i kerosee which is also a o-polar solvet. ut the same Naphthalee does't dissolve i water which is a polar solvet. Solubility of KOH, NaNO 3, KNO 3, NH 4 Cl icrease with the icrease i temperature. Solubility of Ce 2 (SO 4 ) 3 ad all gases decrease as the temperature icreases. Effect of temperature is egligible with respect to NaCl solubility. Cocetratio of Solutio: Cocetratio solutio is expressed by the followig methods. (1) Weight percetage = w 100 w + W (2) Volume percetage = v 100 v + V (3) Molarity = w 1000 gram molecular weight v where 'v' is i milli litres. w 100 = gram molecular weight V where 'V' is i litres. (4) Mole fractio (X No.of molesof costituets Total o.of molesof all costituet preset i the solutio If moles of solute is dissolve i moles of solvet the Mole fractio of (X o.of moles of Total o.of moles = + Mole fractio of (X o.of moles of Total o.of moles = + X + X = + = 1 + +

3 Ioizatio of Substaces i Water: Ioizatio: The process of a molecule givig rise to ios is called ioizatio. Weak Electrolytes: Substaces which ioize i completely are kow as weak electrolytes. Eg: CH 3 COOH, NH 4 OH Strog Electrolytes: Substaces which ioize completely are kow as strog electrolytes. Eg: NaCl, KCl, NaNO 3, KNO 3 No-Electrolytes: Substaces which do ot ioize is called as a o-electrolyte. Eg: Glucose, Sucrose, Urea. (Stadard Flask: Stadard solutio ie kow cocetrated solutio is prepared with the help of a stadard flask) Importat Questios from Solutios: 5 Mark Questios: 1. Draw the diagram of stadard flask ad metio their capacities. 4 Mark Questios: 1. Make a brief ote about the factors that affect solubility of a substace. s- Factors affectig solubility of substaces. (a) Nature of solute & solvet. (b) Temperature. Geerally polar substaces dissolve i polar solvets, but ot i a o-polar solvets. I the same maer o-polar substaces dissolve i o-polar solvets but ot i polar solvets. Eg (1): Copper Sulphate is a polar solute. Hece it dissolves i water which is also a polar solvet. ut the same copper sulphate does't dissolve i kerosee as kerosee is a o-polar solvet. Eg (2): Naphthalee is a o-polar solute. Hece it dissolves i kerosee which is also a o-polar solvet. ut the same Naphthalee does't dissolve i water which is a polar solvet. Solubility of KOH, NaNO 3, KNO 3, NH 4 Cl icrease with the icrease i temperature. Solubility of Ce 2 (SO 4 ) 3 ad all gases decrease as the temperature icreases. Effect of temperature is egligible with respect to NaCl solubility. 2. How do you prepare 0.1M stadard Na 2 solutio usig 250 ml stadard flask? (Molecular Weight of Na 2 = 106) [March-2001]. To prepare 0.1M stadard Na 2 solutio usig 250 ml flask.

4 (1) Molarity = W 1 W 1 ( vol.i litre ); 0.1 = GMW V W = 2.65 gm (2) Thus we eed 2.65 gm of Na 2 to prepare 0.1M Na 2 solutio i 250 ml flask. (3) Trasfer this Na 2 ito 250 ml stadard flask with the help of a fuel. (4) Rise the walls of fuel with distilled water effect quatitative trasfer. (5) Shake getly the flask till the solid is dissolved. (6) Make up the solutio to the mark of the flask with distilled water. (7) Close the flask ad ivert it several times to make the homogeeous solutio. 3. Defie molarity ad mole fractio ad give their equatios. [March-09, 03, Jue-01] (a) Molarity: The umber of moles of solute preset i a litre of solutio is called molarity. It is measured i moles/litre ad deoted by the symbol 'M'. (b) M = Molarity = W W 1 = M = V i litres GMW GMW V Mole fractio: The ratio of umber of moles of a costituet to the total umber of moles of all costituets of a solutio is called mole fractio of a costituet. It has o uits. = o. of moles of, = o.of moles of Mole fractio of (X + Mole fractio of (X X + X = 1 V = o.of molesof solute volume of solutio i litres ( ) + Problems (4 Marks) 1. Calculate the moles of oxalic acid preset i 400 ml of its 0.025M solutio. (Oct-1999) Sol: Molarity = 0.025M volume i litres = 400 ml / 1000 No.of moels of solute = Molarity V i litres = /1000 = grams of Na 2 preset i 120 grams of its aqueous solutio. Calculate the weight %. (Jue-2004) Sol: Weight of solute w = 10 grams

5 Weight of solutio w + W = 120 grams w 10 W% = 100 = 100 = 8.33 w + W ml of alcohol is mixed with 160 ml. Fid out the v% of this solutio. (March-2007) v V% = 100 = 100 = 100 = 11.11% v + V ml of hexae is mixed with 45 ml of heptae. Calculate the V% of this solutio. (Solutio similar to 4 th problem) (Jue-2003) Volume of solute (v 15ml Volume of solvet(v 45ml Total volume of Solutio = v+v = = 60ml 15/60 X100 =25 v V% = 100 = v + V V% = grams of Sodium Carboate (Na 2 ) is preset is 0.25 litres of its solutio. Calculate the molarity of the solutio. (Mol. wt of Na 2 is 106) (Jue-2010) Weight of solute (w 2.12gms Volume of solvet = 250ml Gram Molecular weight of Na 2 = 106 Molarity = = 2.12/106 x 1/0.125 = 0.08M Short Questios (2 Marks) 1. Copper Sulphate is soluble i water, but ot i kerosee. Give reaso? (March-2008). oth copper sulphate ad water are polar substaces. Hece copper sulphate dissolves i water. Sice kerosee is a o-polar solvet copper sulphate does't dissolve i kerosee. 2. What are strog electrolytes? Give some examples?. Substaces which ioize completely are kow as strog electrolytes. Eg: NaCl, KCl, NaNO 3, NaOH.

6 3. What are weak electrolytes? Give some examples?. Substaces which ioize icompletely are kow as weak electrolytes. Eg: CH 3 COOH, NH 4 OH etc. 4. What are o-electrolytes? Give some examples?. Substaces which do ot ioize are kow as o-electrolytes. Eg: Sucrose, Urea ad Glucose. 5. Why Naphthalee soluble i Kerosee but ot i water?. oth Naphthalee ad Kerosee are o-polar substaces. Hece Naphthalee dissolves i Kerosee. Sice water is a polar solvet Naphthalee does't dissolve i water. Very Short Questios (1 Mark) 1. What is meat by stadard solutio?. Whe the cocetratio of solutio is kow it is called stadard solutio. 2. Give oe example for each of polar ad o-polar solvets? (March-1999). Polar solvet: Water, o-polar solvet: Kerosee. 3. Defie volume percetage?. The volume of solute preset i 100 ml of solutio is called "volume percetage" V%. v V% = 100 v + V 4. Defie weight percetage?. The weight of solute preset i 100 grams of solutio is called weight percetage. w W% = 100 w + W 5. What is meat by ioizatio?. The process of a molecule givig rise to ios is called "Ioizatio". Fill i the laks (1/2 Mark Questios) 1. Whe 10 grams of Na 2 is preset i 120 grams of aqueous solutio the w% is (Jue-2005) 2. The amout of oxalic acid required to prepare 100 ml 0.2M solutio (Mol.wt. of Oxalic cid is 126) (Jue-2006) grams of Na 2 is dissolved i 190 gms of water, the w% of solutio is (March-05, 09) 4. 4 ml of alcohol dissolved i 36 ml of water. The volume percetage of solutio is (Jue-2010, 07, March-2006, 2000)

7 5. Molecular weight of Na 2 is (March-08) 6. Molecular weight of H 2 SO 4 is grams of Na 2 is preset i 120 grams of its aqueous solutio. The weight percetage of solutio is (March 02, Jue-03) 8. If 2 moles of Na 2 is dissolved i 3 moles of water the mole fractio of water is (Jue-2000) 9. Stadard solutio is prepared i 10. The sum of mole fractio of solute ad solvet is equal to 11. Solubility of gases with icrease i temperature swers: / gm Stadard flask 10. oe 11. decreases

What Is Required? You need to determine the hydronium ion concentration in an aqueous solution. K w = [H 3 O + ][OH ] =

What Is Required? You need to determine the hydronium ion concentration in an aqueous solution. K w = [H 3 O + ][OH ] = Calculatig the [H3O + ] or [OH ] i Aqueous Solutio (Studet textbook page 500) 11. The cocetratio of hydroxide ios, OH (aq), i a solutio at 5C is 0.150 /. Determie the cocetratio of hydroium ios, H 3 O