Question:In Experiment 9, a 1.05 g sample of a mixture of NaCl (MW 58.45) and NaNO2 (MW 69.01) is reacted with excess sulfamic acid. The sample is 40.00% by mass NaNO2. Only NO21- reacts according to the equation below. The nitrogen gas that is formed is collected over water at a temperature of 22.0°C and the barometric pressure on the day of the experiment was 750.0 mm Hg. The vapor pressure of water at 22.0°C is 19.8 mm Hg. What is the volume of nitrogen collected?

NO21- (aq) + HSO3NH2  ® HSO41-(aq) + H2O(l) + N2(g)

(a) 149 mL     (b) 384 mL    (c) 376 mL

(d) 75.0 mL      

34.      A 0.100 g sample of phosphoric acid (MW 99.0 g/mol), a tri-protic acid, requires 35.0 mL of a NaOH solution for neutralization. What is the molarity of the NaOH solution?

(a) 0.0433 M              (b) 0.0289 M      (c) 43.3 M

(d) 9.62×10−3 M                     

36.      

37.      An engineering student is conducting a calorimetry experiment. She has previously determined that the heat capacity of the calorimeter itself is 159 J/ºC.  In the experiment she mixes 50.0 mL of 2.03 M Ca(OH)2 and 50.0 mL of 1.98 M HCl(aq) according to the equation below. The temperature increases from 25.0 ºC to 35.0 ºC. The density of the CaCl2(aq) solution produced is 1.04 g/mL and the specific heat of the solution is 3.93 J/g-ºC. What is q (in units of J) for the reaction in the calorimeter? (NOT J/mol)

           Ca(OH)2(aq) + 2 HCl(aq) ® CaCl2(aq) + 2 H2O(l)          

(a) +4.09×103 J                       3                       (c) +5.68×103 J

(d) -4.09×102 J                      (e) -5.74×105 J