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Calculate the percentage mass of copper in the ore sample?
I'm struggling to even attempt to begin solving this question.
A sample of ore from a copper mine contains a mixture of copper sulfate, copper sulfide and copper oxide. A finely ground sample of this material (10.32g) was treated with sulfuric acid to dissolve all of the copper compounds. The resulting sample was filtered to remove undissolved material. An excess of sodium hydroxide was added that caused the copper to precipitate as copper hydroxide (Cu(OH)2). The copper hydroxide precipitate was filtered then briefly washed with cold water to remove any soluble salts, then thoroughly dried to give a constant mass of 2.31g.
Calculate the percentage mass of copper in the copper ore sample.
Any help is appreciated!
thanks so much
3 Answers
- gobob3000Lv 67 years agoFavorite Answer
In a total sample of 10.32g of ore, we have 2.31g of Cu(OH)2.
First, let's find the fraction Cu is in Cu(OH)2?
Get the atomic weights:
Cu 63.546
O 15.9994
H 1.00794
Total Molecular weight of Cu(OH)2 is=
63.546 + 2 (15.9994 + 1.00794) = 97.56068
What fraction of this is Cu?
63.546 / 97.56068 = .65134847
Multiple this fraction by the ratio of the weight of our refined sample to the weight of the total ore sample
.65134847 * (2.31/10.32) = .14579602
So about 14.579602% of our ore sample is Cu.
Preserving 3 significant digits, we should indicate about 14.6% of our ore sample is Cu.
- Anonymous5 years ago
That's actually an interesting question
