Self Test

An aqueous solution of sodium hydroxide contains 30% NaOH by mass. It is desired to produce an 8% NaOH solution by diluting a stream of the 30% solution with a stream of pure water. Calculate the ratios (g H₂0/g feed solution) and (g product solution/ g feed solution), and determine the feed rates of 30% solution and diluting water needed to produce 100 lb_m/min of the 8% solution.

To solve this problem first we must

        1) Choose a basis for calculations.
        2) Draw and label a flowchart
        3) Create a table

We will use a basis of 100 lb_m/min of Product solution

Picture the flowchart for this system. If you need some help click on either of the buttons below.

Because we have three streams in a binary system (two components) our table will have three rows and three columns.

Before we begin filling in data it is important to label the row sand columns accordingly, this is done for you in the table below.

Streams \ Components	Total	NaOH	Water
Feed 1 (NaOH solution)
Feed 2 (Pure water)
Output

Now we are ready to start entering mass flow rate data. (Note: all data in the table has units of lb_m/min)

Begin with entering any information explicitly stated in the problem according to our chosen basis.

Then proceed with mass balances on each component and an overall mass balance.

Once you have completed the table, or if you get stuck and need a hint, click on the button below to check you answers.