The percentage of CHO in vitiamin C was determined by buring a simple weighing 2.00mg.
The masses of carbon(iv)oxide and water formd are 3.00mg and 0.816mg respectively.
From this, find the percentage of each element and the emperical formular of vitamin C?
mass C = 3.00 mg x (12/44) = 0.818 mg
mass H = 0.816 x (2/18) = 0.0906 mg
mass O = mass sample - mass C - mass H = 2.00 - 0.818 - 0.0906 = 1.09 mg
mols C = 0.818/12 = 0.0682
mols H = 0.0906/1 = 0.0906
mols O = 1.091/16 = 0.0682
Divide by the smallest to obtain smallest ratio of 1 to obtain
C = 0.0682/0.0682 = 1
H = 0.0906/0.0682 = 1.33
O = 0.06820.0682 = 1
Now recalculate to make the ratios even numbers by multiplying H by 3 to obtain
C = 1 x 3 = 3
H = 1.33 x 3 = 3.99 and round to 4
O = 1 x 3 = 3
So empirical formula is C3H4O3.
How come the 3.00mg the mass of carbon instead of CO2. Please explain
To find the percentage of each element in vitamin C, we need to calculate the masses of carbon, hydrogen, and oxygen in the sample.
Given:
Mass of carbon dioxide = 3.00 mg
Mass of water = 0.816 mg
First, let's find the mass of carbon. Since carbon dioxide (CO2) contains one carbon atom per molecule, the mass of carbon can be calculated by converting the mass of carbon dioxide to carbon:
Mass of carbon = Mass of carbon dioxide / (molar mass of carbon dioxide * (mass of carbon / molar mass of carbon))
The molar mass of carbon dioxide (CO2) is: 44 g/mol
The molar mass of carbon (C) is: 12 g/mol
Mass of carbon = 3.00 mg / (44 g/mol * (12 g/mol / 12 g/mol))
Mass of carbon = 3.00 mg / 44
Next, let's find the mass of hydrogen. Since water (H2O) contains two hydrogen atoms per molecule, the mass of hydrogen can be calculated by converting the mass of water to hydrogen:
Mass of hydrogen = Mass of water / (molar mass of water * (mass of hydrogen / molar mass of hydrogen))
The molar mass of water (H2O) is: 18 g/mol
The molar mass of hydrogen (H) is: 1 g/mol
Mass of hydrogen = 0.816 mg / (18 g/mol * (2 g/mol / 1 g/mol))
Mass of hydrogen = 0.816 mg / 36
Finally, let's find the mass of oxygen. Since vitamin C contains only carbon, hydrogen, and oxygen, we can find the mass of oxygen by subtracting the sum of the masses of carbon and hydrogen from the total mass of the sample:
Mass of oxygen = Total mass - (Mass of carbon + Mass of hydrogen)
Total mass = 2.00 mg
Mass of oxygen = 2.00 mg - (mass of carbon + mass of hydrogen)
Now, we can calculate the percentage of each element:
Percentage of carbon = (Mass of carbon / Total mass) * 100
Percentage of hydrogen = (Mass of hydrogen / Total mass) * 100
Percentage of oxygen = (Mass of oxygen / Total mass) * 100
Lastly, to determine the empirical formula of vitamin C, calculate the mole ratios of carbon, hydrogen, and oxygen by dividing their masses by their respective molar masses. Then, divide all the ratios by the smallest ratio to obtain whole number subscripts. The resulting subscripts will give us the empirical formula.
To find the percentage of each element and the empirical formula of vitamin C, we first need to determine the amount of carbon, hydrogen, and oxygen present in the compound.
Step 1: Calculate the moles of carbon, hydrogen, and oxygen:
Molar mass of CO2 (carbon dioxide) = 12.01 g/mol + (2 × 16.00 g/mol) = 44.01 g/mol
Moles of carbon = mass of CO2 / molar mass of CO2 = 3.00 mg / 44.01 g/mol = 0.068175 mol
Molar mass of H2O (water) = 2 × 1.01 g/mol + 16.00 g/mol = 18.02 g/mol
Moles of hydrogen = 2 × (mass of H2O / molar mass of H2O) = 2 × (0.816 mg / 18.02 g/mol) = 0.090333 mol
Since the sample is burned in air, any remaining mass can be attributed to oxygen.
Moles of oxygen = total moles of the sample - (moles of carbon + moles of hydrogen)
= 2.00 mg / molar mass of vitamin C - (0.068175 mol + 0.090333 mol)
Step 2: Calculate the empirical formula:
Find the ratio between the moles of each element by dividing them by the smallest number of moles (oxygen, in this case).
Moles of carbon = 0.068175 mol / 0.068175 mol = 1
Moles of hydrogen = 0.090333 mol / 0.068175 mol = 1.325
Moles of oxygen = (Total moles of the sample - (moles of carbon + moles of hydrogen)) / 0.068175 mol
Based on the ratio, we can round off the number of moles (if necessary) to obtain whole number ratios.
Therefore, the empirical formula of vitamin C is CH1.325O(moles of oxygen).
Step 3: Calculate the percentage of each element:
To find the percentage by mass, we need to calculate the mass of each element in the vitamin C compound.
Mass of carbon = moles of carbon × molar mass of carbon = 1 × 12.01 g/mol = 12.01 g
Mass of hydrogen = moles of hydrogen × molar mass of hydrogen = 1.325 × 1.01 g/mol = 1.33725 g
Mass of oxygen = moles of oxygen × molar mass of oxygen = moles of oxygen × 16.00 g/mol
The percentage of each element can be calculated using the mass of each element and the total mass of the compound:
Percentage of carbon = (mass of carbon / total mass of compound) × 100
Percentage of hydrogen = (mass of hydrogen / total mass of compound) × 100
Percentage of oxygen = (mass of oxygen / total mass of compound) × 100
Substitute the calculated values into the formulas above to find the percentages of each element.