A mixture of KCl and KBr weighing 3.595 g is heated with chlorine, which converts the mixture completely to potassium chloride. The total mass of potassium chloride after this reaction is 3.129 g. What percentage of the original mixture is KBr?
(I was told the answer to the above question is 34.8%, but I am still unsure how this number was calculated. Could someone please walk me through the steps on how to arrive at this answer? Thank you!)
2006-10-25 09:15:42 · 1 answers · asked by whabtbob 6 in Science & Mathematics ➔ Chemistry
3.595-3.129=0.466
Since Br2 will be liberated we can assume the diffeference in the mass is the Br being replaced with Cl.
Assume 1 mole of Br ion ir replaced with 1 mole Cl ion, this would give a mass loss of 79.904-35.453=44.451g per mole ion replaced
Since 0.466 grams were replaced, 0.466/44.451=0.0105 moles of Br was replaced.
Thus originally there were 0.0105mole KBr* 119.00 (The molecular weight of KBr)=1.250 grams KBr.
1.250 (mass KBr)/3.595 (mass total)=34.8%
2006-10-25 09:47:17 · answer #1 · answered by ence 2 · 1⤊ 0⤋