. How many mL of acetic anhydride (D= 1.082 g/mL) would be needed as starting material to produce 45.0 g of aspirin
I would start with a balanced chem equation. Calculate moles of aspirin from 45g, then use the mole relation in the balanced equation to figure out how much anhydride.
Now in the real world, one has to take in the percent yield as an important factor.
To determine the amount of acetic anhydride (in mL) needed to produce a given amount of aspirin (in grams), we first need to convert the given mass of aspirin to moles. Then, using the balanced chemical equation for the synthesis of aspirin, we can find the molar ratio between acetic anhydride and aspirin. Finally, we can convert the amount of aspirin in moles to the corresponding volume of acetic anhydride in mL using its density.
Let's go step by step:
Step 1: Convert the mass of aspirin to moles.
The molar mass of aspirin (C9H8O4) is calculated by adding the atomic masses present in it: C (12.01 g/mol) x 9 + H (1.01 g/mol) x 8 + O (16.00 g/mol) x 4 = 180.16 g/mol.
To calculate the number of moles of aspirin, divide the given mass of aspirin (45.0 g) by its molar mass:
45.0 g / 180.16 g/mol = 0.2498 mol (rounded to 4 decimal places).
Step 2: Determine the molar ratio between acetic anhydride and aspirin.
From the balanced chemical equation for the synthesis of aspirin:
2 moles of acetic anhydride (C4H6O3) + 1 mole of salicylic acid (C7H6O3) -> 1 mole of aspirin (C9H8O4) + 1 mole of acetic acid (CH3COOH).
There is a 1:1 ratio between acetic anhydride and aspirin. Therefore, for every 1 mole of aspirin, we need 2 moles of acetic anhydride.
Step 3: Convert moles of aspirin to mL of acetic anhydride.
Now we need to convert the moles of aspirin to the corresponding volume of acetic anhydride in mL.
To do this, we can use the molar volume (22.4 L/mol) at standard temperature and pressure (STP), along with the density of acetic anhydride (1.082 g/mL), to convert moles to milliliters.
First, we need to calculate the moles of acetic anhydride required:
0.2498 mol x 2 = 0.4996 mol (rounded to 4 decimal places).
Now, let's convert moles to volume using the molar volume:
0.4996 mol x (22.4 L/mol) x (1000 mL/1 L) = 11183.04 mL (rounded to 2 decimal places).
Therefore, approximately 11183.04 mL of acetic anhydride would be needed to produce 45.0 g of aspirin.