# Chemical measurement questions

I have some basic chemical measurement questions. I have to mix 3% of potassium sulfate with calcium sulfate as an accelerant. How do I calculate the 3%? Base it off 100%? Does this question make sense?

Also, I need to measure out 5cc amounts of powder from a large bucket of powder. Is there a measuring cup for cubic centimeters?

• Who has you measuring chemical powders by volume? The amount of chemical you'd get would be highly dependent on how much settling of the powders there is. I'd highly recommend looking at the source material for your protocol, and seeing if there's a weight equivalent for the 5cc listed anywhere. Measuring powders by volume is only suitable for low-accuracy tasks like cooking. – R.M. Mar 29 '16 at 15:33
• Thank you for taking the time to answer. Appreciate the insight – Jesse Mar 30 '16 at 0:19

Generally a specification like 3% of potassium sulfate is wt%. Such a solution would have 30 g in a about a liter of water (weighing 1 kilogram). $$30/1030 = 2.91 \%$$ which should be close enough. You could use 970 g of water to be more exact. But just filling a beaker to the 1 liter mark would work fine.
I never though of cooking in Europe, but I'd guess that they do have measuring spoons in some $\mathrm{cm}^3$ (mL) units. Again good enough would almost certainly work. $$1 \text{ teaspoon} = 4.92892 \text{ mL}$$