4 Fe + 6 H₂O + 3 O₂ → 4 Fe(OH)₃ Police found 10 grams of Fe(OH)₃ on the knife. Convert grams of rust (Fe(OH)₃) into grams of iron (Fe) to see if the knife contained enough to murder the butler.

345 g Fe

5.22 g Fe

7.34 g Fe

2.95 g Fe

Phosphoric acid is a triprotic acid ( =6.9×10−3 , =6.2×10−8 , and =4.8×10−13 ). to find the ph of a buffer composed of h2po−4(aq) and hpo2−4(aq) , which p value should be used in the henderson–hasselbalch equation? p k a1 = 2.16 p k a2 = 7.21 p k a3 = 12.32 calculate the ph of a buffer solution obtained by dissolving 18.0 18.0 g of kh2po4(s) kh 2 po 4 ( s ) and 33.0 33.0 g of na2hpo4(s) na 2 hpo 4 ( s ) in water and then diluting to 1.00 l.