1. In the introduction to this experiment, it states that you reacted 2.5 grams of salicylic acid with an excess of acetic anhydride, meaning that there would be a higher number of moles of acetic anhydride then salicylic acid, proportionally. Assuming the density of acetic anhydride is 1.082 g/ml, and the molecular formula is C4H6O3, show how this is true.
To show how there would be a higher number of moles of acetic anhydride than salicylic acid, we need to compare their molecular weights and use the given mass of salicylic acid.
1. Start by finding the molecular weight of salicylic acid (C7H6O3):
- Carbon (C) has a molar mass of 12.01 g/mol.
- Hydrogen (H) has a molar mass of 1.01 g/mol.
- Oxygen (O) has a molar mass of 16.00 g/mol.
- Multiply the molar masses of carbon, hydrogen, and oxygen by their respective subscripts in the formula, and sum them up:
Molecular weight of salicylic acid = (7 × 12.01) + (6 × 1.01) + (3 × 16.00) = 138.12 g/mol
2. Now, we can calculate the number of moles of salicylic acid using the given mass (2.5 g) and the molecular weight we just calculated:
Moles of salicylic acid = mass / molecular weight = 2.5 g / 138.12 g/mol
3. Next, we need to find the molar ratio between salicylic acid and acetic anhydride. The balanced chemical equation for the reaction will provide this information. Let's assume the balanced equation is:
1 mol salicylic acid + x mol acetic anhydride → products
4. Finally, we can use the molar ratio to find the number of moles of acetic anhydride. Since it's stated that there is an excess of acetic anhydride, the number of moles should be higher than the moles of salicylic acid:
Moles of acetic anhydride = x * moles of salicylic acid
To find the value of x, we need additional information. Please provide the balanced chemical equation for the reaction between salicylic acid and acetic anhydride.