Please help!! A compound contains only carbon, hydrogen, and oxygen. Combustion
ID: 539499 • Letter: P
Question
Please help!!
A compound contains only carbon, hydrogen, and oxygen. Combustion of 65.17 g of the compound yields 97.70 g of CO2 and 26.66 g of H2O.
The molar mass of the compound is 176.1 g/mol.
*Each part of this problem should be submitted separately to avoid losing your work*
1. Calculate the grams of carbon (C) in 65.17 g of the compound: grams
2. Calculate the grams of hydrogen (H) in 65.17 g of the compound. grams
3. Calculate the grams of oxygen (O) in 65.17 g of the compound. grams
Based on your previous answers, calculate
1. the moles of carbon (C) in 65.17 g of the compound: moles
2. the moles of hydrogen (H) in 65.17 g of the compound: moles
3. the moles of oxygen (O) in 65.17 g of the compound: moles
Divide each mole quantity that you determined in the previous question by the smallest number of moles to determine the correct empirical formula.
Enter the correct subscript for each atom using the smallest whole number.
Enter a 1 if that is the smallest whole number, don't leave the box empty. C H O
Now determine the molecular formula. Remember that the molar mass of the compound is 176.1 g/mol.
Enter the correct subscript for each atom using the smallest whole number.
Enter a 1 if that is the smallest whole number, don't leave the box empty.
C H O
Tries 0/10Explanation / Answer
let in compound number of moles of C, H and O be x, y and z respectively
Number of moles of CO2 = mass of CO2 / molar mass CO2
= 97.7/44
= 2.2205
Number of moles of H2O = mass of H2O / molar mass H2O
= 26.66/18
= 1.4811
Since 1 mol of CO2 has 1 mol of C
Number of moles of C in CO2= 2.2205
so, x = 2.2205
Since 1 mol of H2O has 2 mol of H
Number of moles of H = 2*1.4811 = 2.9622
mass O = total mass - mass of C - mass of H
we have:
mass of C = number of moles of C *molar mass of C = 2.2205*12 = 26.646 g
mass of H = number of moles of H *molar mass of H = 2.9622*1 = 2.9622 g
put these values in:
mass O = total mass - mass of C - mass of H
= 65.17 - 2.2205*12 - 2.9622*1
= 35.5623 g
number of mol of O = mass of O / molar mass of O
= 35.5623/16
= 2.2226
so, z = 2.2226
Answer 1: 26.646 g
Answer 2: 2.9622 g g
Answer 3: 35.5623 g
Answer 4: 2.2205 mol
Answer 5: 2.9622 mol
Answer 6: 2.2226 mol
Divide by smallest to get simplest whole number ratio:
C: 2.2205/2.2205 = 1
H: 2.9622/2.2205 = 1.33
O: 2.2226/2.2205 = 1
multiply all by 3 to get whole number:
C: 1*3 = 3
H: 1.33*3 = 4
O: 1*3 = 3
So empirical formula is:C3H4O3
Answer: 3,4,3
Molar mass of C3H4O3,
MM = 3*MM(C) + 4*MM(H) + 3*MM(O)
= 3*12 + 4*1 + 3*16.0
= 88 g/mol
Now we have:
Molar mass = 176.1 g/mol
Empirical formula mass = 88 g/mol
Multiplying factor = molar mass / empirical formula mass
= 176.1/88
= 2
Hence the molecular formula is : C6H8O6
Answer: 6,8,6