Certainly! I can provide examples of calculating relative atomic mass from percent composition and vice versa.
- Calculating Relative Atomic Mass from Percent Composition:
Example: Find the relative atomic mass of a compound that consists of 40% carbon (C), 6.7% hydrogen (H), and 53.3% oxygen (O).
Solution: Step 1: Convert the percentages to decimal form by dividing each percentage by 100. Carbon: 40% = 0.40 Hydrogen: 6.7% = 0.067 Oxygen: 53.3% = 0.533
Step 2: Determine the number of moles of each element by dividing the decimal percentage by its atomic mass. Carbon: 0.40 / 12.01 g/mol = 0.033 moles of carbon Hydrogen: 0.067 / 1.008 g/mol = 0.067 moles of hydrogen Oxygen: 0.533 / 16.00 g/mol = 0.033 moles of oxygen
Step 3: Calculate the sum of the masses of all the elements. Mass of carbon = 0.033 moles × 12.01 g/mol = 0.396 g Mass of hydrogen = 0.067 moles × 1.008 g/mol = 0.068 g Mass of oxygen = 0.033 moles × 16.00 g/mol = 0.528 g
Step 4: Add up the masses of all the elements to obtain the relative atomic mass. Relative atomic mass = Mass of carbon + Mass of hydrogen + Mass of oxygen = 0.396 g + 0.068 g + 0.528 g = 0.992 g
Therefore, the relative atomic mass of the compound is 0.992 g/mol.
- Calculating Percent Composition from Relative Atomic Mass:
Example: Determine the percent composition of a compound with a relative atomic mass of 60.08 g/mol, consisting of carbon (C) and oxygen (O).
Solution: Step 1: Determine the molar mass of each element. Carbon: Atomic mass of carbon = 12.01 g/mol Oxygen: Atomic mass of oxygen = 16.00 g/mol
Step 2: Determine the number of moles of each element present in one mole of the compound. Let x be the number of moles of carbon. Since the relative atomic mass is 60.08 g/mol, the molar mass of carbon in the compound is 12.01x g/mol. The molar mass of oxygen in the compound is (60.08 - 12.01x) g/mol.
Step 3: Set up an equation using the molar masses and solve for x. 12.01x + (60.08 - 12.01x) = 60.08 12.01x + 60.08 - 12.01x = 60.08 0x + 60.08 = 60.08 60.08 = 60.08
Since the equation is true for any value of x, it means that the compound consists of equal moles of carbon and oxygen.
Step 4: Calculate the percent composition. Percent composition of carbon = (mass of carbon / molar mass of the compound) × 100% = (12.01 g / 60.08 g) × 100% = 20% Percent composition of oxygen = (mass of oxygen / molar mass of the compound) × 100% = (16.00 g / 60.08 g) × 100% = 26.65%
Therefore, the compound has a percent composition of 20% carbon and 26.65% oxygen.
These examples demonstrate how to calculate relative atomic mass from percent composition and vice versa.