Ch. 9 & 13 stoichiometry & gas                                 [50 points]                   Honors Chemistry

For problems involving calculations, show your work in an organized manner, include any relevant equation (or formula and conversion factor(s)), put the proper units in your calculations / answer, and have the proper number of significant figures in your answer.   

 

1. What is the mass of the precipitate formed by mixing aqueous solutions containing 100.0 g silver nitrate and 100.0 g copper (II) nitrate ?  [15 points]

2. A 2.0 L container at STP has 4.0 g H2 , 40. g O2 , and 60. g N2 . What is the partial pressure of O2 ? [10 points]

 

3. H2 O2 (aq) --> H2 O (l) + O 2 (g)
How many grams of H2O2 would decompose if there was 5.0 L O2 at 25 °C and 1.0 atm formed in the above reaction ? [15 points]

 

4. What is the % yield in the chemical reaction: excess N2   +  5.0 g H2    -->   20.0 g NH3 ?  [10 points]


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Ch. 9 & 13 stoichiometry & gas                     retest   [50 points]                   Honors Chemistry

 

1. What is the mass of the precipitate formed by mixing aqueous solutions containing 100.0 g calcium nitrate and 100.0 g sodium phosphate ?  [15 points]

 

2. A container at STP has 4.0 g H2 , 40. g O2 , and 60. g N2 .   [10 points]

a.  What is the partial pressure of O2 ?

b.  what is the volume of the container ?

 

3. A 35 mg sample containing copper and magnesium was added to HCl, where

Mg (s)   +  excess HCl (aq) --> MgCl2 (aq) + H2 (g)

where got 35 mL gas (assume PH2O =  20 mm Hg & ΔP = 0) at 22 °C and 0.95 atm;  HCl does not react with Cu.

What is the % Cu in the sample before HCl treatment ?  [15 points]

 

4. The % yield in the chemical reaction: N2   +   H2    -->   NH3  is 80 %.  How much H2 (there is excess N2 )  is needed to form 15.0 grams of  NH3   ?  [10 points]