Chemistry Assignment Help Questions and Answers part1

Select the best answer in the following

Use the following to answer question 1:

The solubility of silver phosphate (Agl04) at 25°C is 1.6 ~ 10-5 mol/L.

1. Determine the concentration of the Ag+ ion in a saturated solution.

 A) 7.6 x 10-5 M   B) 6.4 x 10-5 M   C) 1.6 x 10-5 M   D) 3.2 x 10-5 M   E) 4.8 x 10-5 M

2. Which statement below is not upheld by the second law of thermodynamics?

A) A machine is never 100%efficient.

B) Machines always waste some energy.

C) The change of entropy of the universe is always positive.

D) The entropy of a perfect crystal at 0 K is zero.

E) All of these

3. The pH in a solution H2A of 1.0 M (Ka1= 1.0 x 10-6; Ka2 = 1.0 x 10-1°) is:

 A) 6.00    (B) 3.00   (C) 7.00    D) 8.00    E) none of these

4. Assume that the enthalpy of fusion of ice is 6020 J/mol and does not vary appreciably over the temperature range 270-290 K. If one mole of ice at O°C is melted by heat supplied from surroundings at 280 K, what is the entropy change in the surroundings, in JIK?

 A) +22.0    B) -21.5      C) -22.0     D) 0.0    ) +21.5

Use the following to answer questions 5-7:

Determine whether the following oxides produce an acidic, basic, or neutral solution when dissolved in water:

5. MgO     

6. Na2O     

7. P4O10   

Use the following to answer question 8:

See the following reaction at constant 25°C and 1 atm.

2Fe(s) + (3/2) O2 (g) + 3H20(l) ~ 2Fe (OH)3(s)     DeltaH = kJ/mol

Substance         SO (J/mol K)

 Fe (OH)3(s)       107

Fe(s)                    27

O2 (g)               205

H20 (l)                70

9. One milliliter (1.00 mL) of acid taken from a lead storage battery is pipetted into a flask. Water and phenolphthalein indicator are added, and the solution is titrated with 0.50 M NaOH until a pink color appears;12.0 mL are required.

 The number of grams ofH2SO 4 (formula weight = 98) present in one liter of the battery acid is (to within 5%)

A) 750     B) 240      C) 290       D) 480       E) 580

10. Calculate the pH at the equivalence point for the titration of 1.0 M ethylamine, C2H5NH2 by 1.0 M per chloric acid, HCIO4' (pKb for C2H5NH2 = 3.25)

A) 5.38   B) 5.53   C) 2.09   D) 2.24    E) 6.05

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Chemistry Assignment Help Questions and Answers part2 available at http://goo.gl/KBpGe
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