Question

16. How many grams of steam and iron must react to produce 375 g of magnetic iron oxide, Fe₃O₄?

3 Fe_(s) + 4 H₂O_(g)  Fe₃O_4(s) + 4 H_2(g)

18. Mercury can be isolated from its ore by the reaction

4 HgS + 4 CaO → 4 Hg + 3 CaS + CaSO₄

(a) How many moles of CaS are produced from 2.5 mol CaO?

(b) How many grams of Hg are produced along with 9.75 mol of CaSO₄?

(c) How many moles of CaO are required to react with 97.25 g of HgS?

(d) How many grams of Hg are produced from 87.6 g of HgS?

(e) How many grams of CaS are produced along with 9.25 kg of Hg?

16. How many grams of steam and iron must react to produce 375 g of magnetic iron oxide, Fe₃O₄?

3 Fe_(s) + 4 H₂O_(g)  Fe₃O_4(s) + 4 H_2(g)

18. Mercury can be isolated from its ore by the reaction

4 HgS + 4 CaO → 4 Hg + 3 CaS + CaSO₄

(a) How many moles of CaS are produced from 2.5 mol CaO?

24. In the following equations, determine which reactant is the limiting reactant and which reactant is in excess. The amounts used are given below each reactant. Show evidence for your answers.

(b) 3 Fe + 4 H₂O → Fe₃O₄ +4H₂

40.0 g     16.0 g

26. Phosphorous trichloride, a precursor for the manufacture of certain pesticides and herbicides, can be produced by the reaction of phosphorous and chlorine:

P₄ + 6 Cl₂ → 4 PCl₃

(a) When 20.5 g of P₄ and 20.5 g of Cl₂ are reacted, how many moles of PCl₃ can be produced?

(b) When 55 g of Cl₂ are reacted with 25 g of P₄, how many grams of PCl₃ can be produced? Which reactant is in excess?

(c) In a reaction vessel, 15 mol of P₄ and 35 mol of Cl₂ react. Determine which substances will be present in the container after the reaction goes to completion and how many moles of each substance is present.

30. Chromium metal can be produced by the reduction of Cr₂O₃ with elemental silicon:

2 Cr₂O₃ + 3Si → 4 Cr + 3 SiO₂

If 350.0 grams of Cr₂O₃ are reacted with 235.0 grams of elemental silicon and 213.2 grams of chromium metal are recovered, what is the percent yield?

32. In aqueous solution, metal oxides can react with acids to form a salt and water:

Fe₂O_3(s) + 6 HCI_(aq) → 2 FeCl_3(aq) + 3 H₂O_(l)

(a) How many moles of each product will be formed when 35 g of Fe₂O₃ react with 35 g of HCl?

(b) From part (a), how many grams of the excess reactant remain?

(c) If the percent yield of FeCl₃ is 92.5%, what is the actual yield in grams?