Supplemental Instruction
Iowa State University / Leader: / James
Course: / ChE 160
Instructor: / Heinen/ Stiehl/ Brenza
Where: The best location is in your Eide textbook. They should have most of what you need. Otherwise you could look for the ChE 210 book, Elementary Principles of Chemical Processes. This book is AMAZING.
Discussion
Material balance concepts are THE MOST IMPORTANT concepts to understand in your engineering life. If you don’t know how to balance a system, you will have trouble in every subsequent ChE class. Just a fact.
Concept Questions
What is the basic material balance equation?
What is the difference between batch, semi-batch, and continuous processes?
What are the three basic steps in solving a material balance?
What does it mean for a system to be in steady-state?
Review
A water storage facility has a volume of 110 m3. One inlet pipe provides a flow rate of 17 kg/s. There are two outlets, with flow rates of 1 kg/s and 3.5 kg/s. The storage tank is initially empty.
a. How long will it take to fill the tank if both outlet valves are shut?
b. What if both outlet valves are open?
c. If all valves are open for 2 hours, and the inlet water pump breaks, how long can the outlets supply water?
Leftover acid from a chemical process contains 24 wt% HNO3, 55.0 wt% H2SO4, and 21.0% water. This acid is to be concentrated by adding 92 wt% concentrated H2SO4 as well as 89 wt% concentrated HNO3. The final product must contain 31 wt% HNO3 and 58 wt% H2SO4. Compute the mass of the leftover acid solution and the mass of the concentrated acids added to produce 2.00 x 103 lbm of this desired mixture.
Dilute sulfuric acid (19 wt% H2SO4, the rest water) is required for activating car batteries. A tank of weak acid (12.5% wt% H2SO4) is available. If 450 lbm of 78 wt% concentrated acid is added to create the desired 19 wt% concentration, how much of the dilute acid is now available?
Exam Prep
Practice every problem you can in Eide. This will get you far in understanding basic material balance calculations. And PLEASE remember the Law of Conservation of Mass.