Calculate the percentage by mass of oxygen in the following compounds: a. morphine, C17H19NO3

Verified step by step guidance

1. Step 1: First, we need to calculate the molar mass of the compound. The molar mass of a compound is calculated by adding up the molar masses of each element in the compound. The molar mass of carbon (C) is approximately 12.01 g/mol, hydrogen (H) is approximately 1.01 g/mol, nitrogen (N) is approximately 14.01 g/mol, and oxygen (O) is approximately 16.00 g/mol. For morphine, which has the formula C17H19NO3, the molar mass would be (17*12.01 g/mol) + (19*1.01 g/mol) + (14.01 g/mol) + (3*16.00 g/mol).
2. Step 2: Next, we need to calculate the total mass of oxygen in the compound. This is done by multiplying the number of oxygen atoms in the compound by the molar mass of oxygen. For morphine, this would be 3*16.00 g/mol.
3. Step 3: Now, we can calculate the percentage by mass of oxygen in the compound. This is done by dividing the total mass of oxygen by the molar mass of the compound and then multiplying by 100 to get a percentage. The formula for this calculation is: (mass of oxygen / molar mass of compound) * 100.
4. Step 4: Substitute the values calculated in steps 1 and 2 into the formula in step 3 to find the percentage by mass of oxygen in morphine.
5. Step 5: The result obtained in step 4 is the percentage by mass of oxygen in morphine. Remember to express your answer as a percentage.

Key Concepts

Molar Mass Calculation

Molar mass is the mass of one mole of a substance, typically expressed in grams per mole (g/mol). To calculate the molar mass of a compound, sum the atomic masses of all the atoms in its molecular formula. For morphine (C17H19NO3), this involves calculating the contributions from carbon, hydrogen, nitrogen, and oxygen based on their respective atomic weights.

Percentage by Mass

Percentage by mass is a way to express the concentration of a particular element in a compound. It is calculated by dividing the mass of the element in one mole of the compound by the total molar mass of the compound, then multiplying by 100. This gives a clear representation of how much of the compound's mass is due to a specific element, such as oxygen in morphine.

Empirical and Molecular Formulas

The empirical formula represents the simplest whole-number ratio of elements in a compound, while the molecular formula shows the actual number of each type of atom in a molecule. Understanding the difference is crucial when calculating mass percentages, as the molecular formula of morphine (C17H19NO3) directly informs the molar mass and the subsequent calculations for percentage by mass of oxygen.