SOLUTION: How many pounds of 50% sodium hydroxide does it take to make 1 gallon of 10% solution of sodium hydroxide

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Question 714809: How many pounds of 50% sodium hydroxide does it take to make 1 gallon of 10% solution of sodium hydroxide
Answer by KMST(5328) About Me  (Show Source):
You can put this solution on YOUR website!
At ambient temperature, the density of a 10% solution of sodium hydroxide is 1.11g/mL.
In the absence of other specification, I have to assume that 10 mass units of sodium hydroxide in 100 mass units of solution.
If 10 grams of sodium hydroxide per 100 milliliters of solution were meant the concentration should be stated as 10%(w/v), for weight-in-volume.
The mass of a gallon of that solution would be 4200 grams.
%283785ml%2F1gallon%29%281.11g%2F1mL%29=4201g
The 50% sodium hydroxide would contain 50 grams pure sodium hydroxide per 100 grams of material, so we need
%283785ml%2F1gallon%29%281.11g%2F1mL%29%28100g%2F50g%29=8400g of material.
One pound is 454 grams, so the mass in pounds of material needed would be
%283785ml%2F1gallon%29%281.11g%2F1mL%29%28100g%2F50g%29%281lb%2F454g%29=1.85lb of material.
so it takes 1.85 pounds of 50% sodium hydroxide to make 1 gallon of 10$ solution.