If you have a tank of 51ft long by 4.7ft wide, and need to fill it to the two inch mark with hydrochloric acid, how many pounds are you putting in it? (Hint 1 gallon of acid weights 9.8 lbs.
51 * 4.7 * 2/12 = volume
1 cubic foot = 7.480 519 480 5 gallon [US, liquid]
Convert to gallons and multiply by 9.8