Soru
2. A compound is composed of 39.9987% C, 6.7142% H, and the rest O by mass. When 1.4214 g sample is completely combusted 0.3472 g CO_(2)(g) forms. Find the formula of the compound. A) C_(6)H_(12)O_(6) B) C_(5)H_(12)O_(2) C) C_(6)H_(15)O_(3) D) C_(4)H_(10)O_(2) E) C_(3)H_(6)O_(3)
Çözüm
4.6
(135 Oylar)
Fırat
Usta · 5 yıl öğretmeni
Uzman doğrulaması
Cevap
To find the formula of the compound, we need to determine the moles of each element present in the compound.Given:- 39.9987% C- 6.7142% H- The rest is OStep 1: Calculate the moles of each element in the compound.- Moles of C = (39.9987 / 12.01) = 3.33- Moles of H = (6.7142 / 1.008) = 6.66- Moles of O = (100 - 39.9987 - 6.7142) / 16.00 = 4.00Step 2: Determine the empirical formula by finding the ratio of the moles of each element.- C: 3.33- H: 6.66- O: 4.00Divide each by the smallest number of moles (4.00):- C: 3.33 / 4.00 = 0.83- H: 6.66 / 4.00 = 1.67- O: 4.00 / 4.00 = 1Step 3: Round the ratios to the nearest whole number.- C: 0.83 ≈ 1- H: 1.67 ≈ 2- O: 1Therefore, the empirical formula of the compound is C1H2O1.Step 4: Verify the empirical formula with the given information about the combustion reaction.- 1.4214 g sample completely combusted to form 0.3472 g CO2.- Moles of CO2 = 0.3472 / 44.01 = 0.0079- Moles of C in CO2 = 0.0079 * 1 = 0.0079- Moles of C in the compound = 0.0079 * 12.01 = 0.0947 g- Moles of H in the compound = 0.0079 * 2 = 0.0158 g- Moles of O in the compound = 1.4214 - 0.0947 - 0.0158 = 1.3109 gStep 5: Calculate the moles of each element in the compound.- Moles of C = 0.0947 / 12.01 = 0.0079- Moles of H = 0.0158 / 1.008 = 0.0157- Moles of O = 1.3109 / 16.00 = 0.0822Step 6: Determine the molecular formula by finding the ratio of the moles of each element.- C: 0.0079- H: 0.0157- O: 0.0822Divide each by the smallest number of moles (0.0079):- C: 0.0079 / 0.0079 = 1- H: 0.0157 / 0.0079 = 2- O: 0.0822 / 0.0079 = 10.41Step 7: Round the ratios to the nearest whole number.- C: 1- H: 2- O: 10Therefore, the molecular formula of the compound is C1H2O10.Answer: E)