Practice_EXAM_I

Nowtheequationisupdatedto2ph3o21p2o5h2o

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Unformatted text preview: 94/1 = 5.94; mole of O = 23.49/16 = 1.47. Note that as long as one of the moles is not an integer, we have to divide the smallest value among them: here the smallest value is 1.47. So C : H : O = 5.88/1.47 : 5.94/1.47 : 1.47/1.47 = 4 : 4.04 : 1. Since 4.04 is very close to 4.00 and thus we can round it to 4.00. So C : H : O = 4 : 4 : 1, which indicates that the empirical formula contains four C, four H and one O. Thus, the empirical formula is written as C4H4O as 1 is usually not written in the formula. 20. Chemical analysis shows the composition of a compound containing carbon and hydrogen, to be 80.00% carbon and 20% hydrogen and the molar mass is 30 g. What is its molecular formula? (c) C2H6 (d) C6H12 (e) C10H22 (a) CH (b) C2H4 th th Hint: For 11 ed.: p.p. 89‐90 and Example 3.11; for 9 edition: p.p. 91‐92 and Example 3.11 or p. 109 (3.54). For 10th edition: p. 93: Example 3.11. The molecular formula is an integral multiple of empirical formula. That is, the molar mass = empirical molar mass x integer. From C: H = 80.00/12 : 20.00/1 = 6.66: 20 = 1: 3. So the empiric...
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