Mass Flow Rate Question?

A Solution containing 25gNaCl/100g of water was added @ a steady rate of 50kg/min into a flowing stream n %26amp; the NaCl conc. changed from 3.5% w/w upstream to 4.0% w/w downstream.

how do u calculate the mass flow rate from the above question... i tried and i keep gettin a negative answer

Mass Flow Rate Question?

25 gNACL/100g mean .25 mass ratio.

So the rate of NaCl (by mass) is 50kg*.25= 12.5 kg/min

That is the Sodium rate injected into the stream.

Now if you mean that the stream already had

3.5% NaCl and by injecting that 12.5 kg/min

you now get a stream with 4% NaCl

Then the ratio 12.5 kg/min = X kg/min * .5%

so X = 12.5/.005 = 2500 kg/min is the flow rate of the

rest of the stream.

and so 2500 kg/min * .035 = 87.5 kg/min original NaCl rate

So the total mass flow rate for NaCl is

87.5 + 12.5 = 100 kg/min NaCl flow rate (downstream)