Name:  _____________________                              date:  __________________               period: _______

Ch. 12 & 14  Stoichiometry & gas       test                              60 points                      honors chemistry

Academic Honesty:   The answers on this test are my own and I am using only the allowed set of notes as described in the syllabus.  I have not discussed the test questions with anyone before or during the test nor have I seen the test questions prior to the exam.  If you violate any of the preceding items or do not sign, your semester grade is a F.

                                                                                                Signature:  ___________________

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

1. In the reaction:   KClO3(s)  à  KCl(s)  +   O2(g)

Image result for gas collected over water  
source:  http://wps.prenhall.com/wps/media/objects/3311/3391331/blb1006.html

the volume of the gas collected over water is 250. mL (shown on the right in the above figure) at 26 ºC and pressure in the container is 765 mm Hg.  How many grams of KClO3 was in the reaction ?  [15 points]


2. In the lab that the class didn’t do, a gas was completely vaporized in a 375 cm3 container at 95 ºC at a pressure of 95 kPa.  The gas was condensed and there was 1.012 grams of the gas.  What is the molar mass of the gas ?  [10 points]

3. At STP, 3.0 L of nitrogen gas reacts with 8.0 L of hydrogen gas to produce  ___ grams of ammonia ?  [15 points]

4. If the reaction:  AgNO3(aq)  +  Na3PO4(aq)  à  _______  +  ________  has a % yield of 85%, what the mass of the precipitate if there’s 5.0 millimoles of silver nitrate and 2.0 mmoles of sodium phosphate.  [20 points]