Ch. 9 & 13 stochiometry & gas                                   test                   65 points                                  honors chemistry

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.

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:  ___________________

1.  A sealed syringe has a pressure of 95 kPa, volume of 45 mL, and temperature of 22 ºC.  The syringe’s volume is reduced to 15 mL and its temperature reduced to -5.0 ºC; what is the pressure in the syringe ?  [10 points]

2.  A rigid container at 325 K has a pressure of 95 kPa and contains 8.0 g hydrogen gas, 16 g helium gas, and 80. g argon.  [15 points]

a.  What is the partial pressure of argon in the container ?

b.  what is the volume of the container ?

3. In your recent lab, an unknown mass of magnesium reacts with excess hydrogen chloride to form a gas, which is collected in an eudiometer tube.  The volume of the gas is 35 mL and the room temperature and pressure were 21 ºC and 770 torr, respectively.  The height of the liquid in the eudiometer tube is the same as the level of the water outside of the eudiometer tube.  What is the mass of magnesium before the reaction ?  [15 points]

4.  In the combustion of 5.0  g ethane, C2H6, and 10.0 g oxygen gas, how much water was produced in the reaction ?  [15 points]

5.  5.0 g hydrogen gas reacts with excess nitrogen gas to form ammonia, NH3.  If the percent yield in the reaction is 88%, how many grams of ammonia was produced in the reaction ?  [10 points]