w% CHEM 1083 Exam 2 1. Determine the A) 0 882 olution 2. How many grams 0.02000-

Question

w% CHEM 1083 Exam 2 1. Determine the A) 0 882 olution 2. How many grams 0.02000-M kaMnO aqueous A) 0.1580 9 3. Which of the following is a non electrolyte? 8) 0 8248 g C)0 2377 D) 1.504 4 Whait is the concentration of the chlorde ion in a 0220-M aqueous aluminum chlonde solution? Aluminum chloride is a strong electrolye A) 0 220 M 5. The reaction of strontium oxide and nitric acid proceeds acconding to the following Determine the mass of strontium axide nequired to completely react with 1.034 moles df K-C+27315 Crevee)-Ar forward) B) 0.860 M C)0.440M0132M D) 1.32 M . nitric acid B)5357 g D)51.81 5181g A) 29 26g 6 Determine the volume of 7.19 M HNO, (aa) required to react wth 238kg of sold C)113. 1 g A producta " +4+..+4.1 A) 186L 8)327L C)1.13L 12.7L 7. A 1gram sample of an acid was dissolved in enough waer to reate 100 0mLd aqueous solution. This solution was titrated by 15.00 m/L of 1.058 M NaOH (g) Determine the formula mass of the acid, assuming one acidic proton per formula unit G+ ST A) 60.0 gimol 824.3 g/mol C)63.0 g/mol D) 122 gmol 5-Ixr RT 8. What is the molarity of nitrate ions in an aqueous solution that is prepared by dissolhing 783 milligrams of AlNOnjs into enough water to make 250.0 ml of solution? A) 0.297 M 8) 0.0399 M C)0.0441 M D)0.132 M Mkg (consunt volume) -' cana V-nb)=nRT

Explanation / Answer

First 5 questions answered

1) Given: For aq. Cu(NO3)2solution

Molarity = 2.44 M and volume = 25.06 mL = 25.06 x 10-3 L

Number of moles = Molarity x volume of solution in L

Number of moles of Cu(NO3)2 = 2.44 x 25.06 x 10-3 = 0.0611 moles

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2) For aq. KMnO4 solution

Molarity = 0.0200 M and volume = 75.22 mL = 75.22 x 10-3 L

Number of moles of = 0.0200 x 75.22 x 10-3 = 1.5044 x 10-3 moles

Molar mass of KMnO4 = 158.034 g

It means that

If         1 mole of KMnO4 = 158.034 g

Then, 1.5044 x 10-3 moles of KMnO4 = say A g

A = 1.5044 x 10-3 x 158.034

A = 0.2377 g

0.2377 g of KMnO4 are present.

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3) An electrolyte is a species which dissociates into the its constituent ions on addition to polar solvent like water.

e.g NaCl (aq.) ----------> Na+ (aq.) + Cl- (aq.)

MgSO4 (aq.) ----------> Mg2+ (aq.) + SO42- (aq.)

AlBr3 (aq.) ----------> Al3+ (aq.) + 3Br- (aq.)

And species which do not ionize are termed as non-electrolyte.

e.g. C6H12O6.

Hence C6H12O6 is non-electrolyte.

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4) Aluminium chloride has chemical formula ALCl3

AlCl3 ionizaes in the aqueous phase as,

AlCl3 (aq.) ----------> Al3+ (aq.) + 3Cl- (aq.)

1 molecule of AlCl3 ionizes 3 Cl- ions

Hence its clear that,

[Cl-] = 3 x [AlCl3]

[Cl-] = 3 x 0.220 ……………..(given)

[Cl-] = 0.660 M

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5) Molar masses,

SrO = 103.62 g/mol

HNO3 = 63.01 g/mol

SrO (s) + 2 HNO3 (aq.) ----------> Sr(NO3)2 (aq.) + H2O (l)

From given stoichiometry iits clear that for complete reaction,,

1 mole of SrO requires 2 moles of HNO3

i.e. 2 moles of HNO3 1 mole SrO

so, 1.034 moles of HNO3 say ‘B’ moles of SrO

hence by cross multiplication,

B = (1.034 x 1) /2

B = 0.517

1.034 moles of HNO3 for complete reaction requires 0.517 moles of SrO

Molar mass of SrO =103.62 g

I.e. 1 mole of SrO 103.60 g of SrO

So, 0.517 mole of SrO = say ‘M’ g oof SrO

By crossmultiplying,

M = 103.62 x 0.517

M = 53.57 g

1.034 moles of HNO3 requires 53.57 g of SrO for complete reaction.

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