One method to determine the flow rate of a turbulently flowing stream is to inject a small, metered amount of some easily dispersed fluid and then to measure the concentration of this fluid in a sample of the mixed stream withdrawn a suitable distance downstream. In pharmaceutical plants, there are often Problems 195 many inert gas streams (i. e., streams that contain mostly nonreacting gases). In a particular plant, there is a process stream that is composed of 95 mol% N2 (inert) and 5 mol% O2. To determine the flow rate of this process stream, O2 is injected at a flow rate of 16.3 mol/hr. A downstream sample analyzes the O2 content at 10 mol%. You can assume that no reactions occur in the pipe and that the flows are operating at steady-state. (a) How many balance equations can you write? How many of those are linearly independent? (b) Calculate the flow rate of the process stream containing 95 mol% N2 and 5 mol% O2.