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2Fe + 3Cl₂ ---> 2FeCl₃
4.4mol of Fe, you have a 2:3 ratio of Fe to Cl₂ so divide 4.4/2 = 2.2 and multiply by three 2.2 x 3 = 6.6mol of Cl₂
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Acids react with calcium carbonate and more specifically carbonate to form carbon dioxide. An acid will give protons to the carbonate anion to produce carbonic acid which then decomposes into carbon dioxide and water. I hope this helps. Let me know if anything is unclear.
Bleach and anytype of cleaner like window cleaner or disinfectant is very dangerous because if you mix those two together it might cause a very deadly fume and can cause lung failure and death within about 5 hours