A Stirred Tank with Volume, V, Has a Feed Stream

question 14

Multiple Choice

A stirred tank with volume, V, has a feed stream of concentrated floor cleaner flowing into it at a rate of f . The flow stream has a concentration of c_i. The outlet stream also flows at f but with a concentration of c, the concentration of the floor cleaner solution in the tank. The rate of change of the concentration is proportional to the difference between c_i and c with proportionality constant of f/V: . If the tank volume is 2000 L, the flow rate is 6 L/min, the inlet concentration is 0.9, and the initial concentration of the floor cleaner in the tank is 0.0, how long until the concentration in the tank is 0.7?

• A) 9.0 minutes
• B) 501.4 minutes
• C) 333.3 minutes
• D) 83.8 minutes

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Definitions:

Net Present Value

A financial metric that calculates the difference between the present value of cash inflows and the present value of cash outflows over a period of time, used to assess the profitability of investments.

Future Cash Flows

The projected amounts of money expected to be received or paid out by an entity over future periods as a result of investment, operational, and financing activities.

Payback Period

The length of time required to recover the cost of an investment.

Direct Materials

Materials that can be directly linked to the production of a product and represent a substantial portion of the cost.