Tuesday, 17 May 2016

09:45 – Colin and I got several solutions made up yesterday. Today, Barbara and I will fill bottles.

One of the solutions we made up was 4 liters of Benedict’s Reagent, which requires a bunch of sodium citrate. While making up the solution, I saw that we were down to less than 500 g of the reagent grade sodium citrate. I was about to order more when I realized that it made more sense just to stock citric acid. I can dissolve a weighed amount of citric acid in water and neutralize it with the stoichiometric equivalent mass of sodium bicarbonate (baking soda) to yield a solution of sodium citrate, which is just what I need. Also, citric acid and baking soda are both cheap, at about $2.70/lb and $0.50/lb respectively, whereas, at about $50/kilo, reagent-grade sodium citrate from a chemical supply company is not. The 10 pounds of citric acid I bought and the baking soda are both FCC/USP (food-grade), which is more than pure enough for making up Benedict’s Reagent. And doing it this way ensures we’ll always have plenty of citric acid (and baking soda) on hand to make up baking powder and various other useful things.