Midterm I Chem 1C Section 20 Version A

Midterm I Chem 1C Section 20 Version A - Midterm I Chem 1C...

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Page 1 Midterm I Chem 1C Section 20 Version A Student: ___________________________________________________________________________ 1. Arsenic acid, H 3 AsO 4 , is used industrially to manufacture insecticides. Arsenic acid is a polyprotic acid with K 1 = 2.5 × 10 -4 , K 2 = 5.6 × 10 -8 , and K 3 = 3 × 10 -13 . What is the concentration of the HAsO 4 2- in a solution whose initial arsenic acid concentration was 0.35 M ? A. 9.4 × 10 -3 M B. 2.5 × 10 -4 M C. 8.8 × 10 -5 M D. 5.6 × 10 -8 M E. none of these choices is correct 2. Write the mass-action expression, Q c , for the following chemical reaction equation. 2C 6 H 6 ( g ) + 15O 2 ( g ) 12CO 2 ( g ) + 6H 2 O( g ) A. B. C. D. E.
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Page 2 3. Nitrogen dioxide can dissociate to nitric oxide and oxygen. 2NO 2 ( g ) 2NO( g ) + O 2 ( g ); H ° rxn = +114 kJ Under which reaction conditions would you expect to produce the largest amount of oxygen? A. high temperature, high pressure B. low temperature, high pressure C. high temperature, low pressure D. low temperature, low pressure E. none of these, unless a catalyst is present 4. Which of the following is considered a Lewis acid? A. CH 3 NH 2 B. BCl 3 C. F - D. BF 4 - E. CH 4 5. The substance HOBr is considered A. a weak Arrhenius acid. B. a weak Arrhenius base. C. a strong Arrhenius acid. D. a strong Arrhenius base. E. a neutral compound. 6. Picric acid has been used in the leather industry and in etching copper. However, its laboratory use has been restricted because it dehydrates on standing and can become shock sensitive. It has an acid dissociation constant of 0.42. What is the [H 3 O + ] for a 0.20 M solution of picric acid? A. 0.022 M B. 0.052 M C. 0.15 M D. 0.29 M E. none of these choices is correct
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Page 3 7. About half of the sodium carbonate produced is used in making glass products because it lowers the melting point of sand, the major component of glass. When sodium carbonate is added to water it hydrolyses according to the following reactions. CO 3 2- ( aq ) + H 2 O( l ) HCO 3 - ( aq ) + OH - ( aq ); K 1 HCO 3 - ( aq ) + H 2 O( l ) H 2 CO 3 ( aq ) + OH - ( aq ); K 2 These can be combined to yield CO 3 2- ( aq ) + 2H 2 O( l ) H 2 CO 3 ( aq ) + 2OH - ( aq ); K 3 What is the value of K 3 ? A.
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Midterm I Chem 1C Section 20 Version A - Midterm I Chem 1C...

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