A student did the Synthesis of Salicylic Acid experiment starting with 3.89 g of methyl salicylate (C8H8O3) and using 40 mL of 6.0 M NaOH. To evaluate her success she needs to determine the limiting reagent. The reaction goes as follows:
C8H8O3 + H2O ==> C7H6O3 + CH3OH.
Assuming the solution of NaOH is mostly water, she uses the volume of NaOH = volume of H2O. Also she assumes that the density of water is 1.000 g/mL. Which is the limiting reagent methyl salicylate or water?
How many moles of salicylic acid can be produced if methyl salicylate is limiting?
How many moles of salicylic acid can be produced if water is limiting?
Which is the limiting reagent: methyl salicylate or water
Convert grams methyl salicylate to moles. moles = grams/molar mass.
Convert grams H2O to moles. same process.
Using the coefficients in the balanced equation, convert moles methyl salicylate to moles salicylic acid (SA). The coefficients are 1:1 which means moles methyl salicylate will be the same as the moles of SA. This procedure effectively tells you that if all 3.89 g methyl salicylate reacted with an excess of NaOH, then ?? moles SA would be formed.
Now do the same for the H2O, which tells you that if all of the H2O reacted with an excess of methyl salicylate, then ?? moles SA would be formed.
The two numbers probably will not agree which means one of them is wrong. The correct answer, in limiting reagent problems, is ALWAYS the smaller value and the reagent producing that smaller value is the limiting reagent.
To determine the limiting reagent in this synthesis reaction, we need to compare the number of moles of each reactant and determine which one is present in the least amount. The reactant that is present in the least amount is the limiting reagent, as it will be completely consumed during the reaction, while the other reactant will be left in excess.
1. Finding the number of moles of methyl salicylate (C8H8O3):
To find the number of moles, we need to divide the given mass by the molar mass of methyl salicylate. The molar mass of C8H8O3 can be calculated by adding up the atomic masses of each element in the compound (12.01 g/mol for C, 1.01 g/mol for H, and 16.00 g/mol for O).
Molar mass of methyl salicylate (C8H8O3) = (8 * 12.01 g/mol) + (8 * 1.01 g/mol) + (3 * 16.00 g/mol)
2. Finding the number of moles of water (H2O):
Given that the volume of NaOH is assumed to be equal to the volume of water, we can convert the given volume of NaOH to grams using its density and then convert it to moles using the molar mass of water (18.02 g/mol).
3. Comparing the number of moles of each reactant:
Compare the number of moles calculated for methyl salicylate and water. The reactant with the lower number of moles is the limiting reagent.
To find the number of moles of salicylic acid produced when methyl salicylate is the limiting reagent, we need to use the stoichiometry of the given reaction.
The balanced equation is:
C8H8O3 + H2O → C7H6O3 + CH3OH
From the equation, we can see that the stoichiometric ratio between methyl salicylate and salicylic acid is 1:1. This means that for every one mole of methyl salicylate, one mole of salicylic acid is produced.
So, the number of moles of salicylic acid that can be produced when methyl salicylate is limiting is equal to the number of moles of methyl salicylate.
To find the number of moles of salicylic acid produced when water is limiting, we need to calculate the number of moles of salicylic acid that can be produced from one mole of water. This can be done by using the stoichiometric ratio of water to salicylic acid, which is 1:1.
Now, compare the number of moles calculated for each case to determine which reactant is limiting. The reactant with the lower number of moles is the limiting reagent.