Aspirin is prepared by reaction of salicylic acid (C7 H6 O3) with acetic anhydride (C4 H6 O3) ac

Aspirin is prepared by reaction of salicylic acid (C7 H6 O3)...

Aspirin is prepared by reaction of salicylic acid $\left(\mathrm{C}_{7} \mathrm{H}_{6} \mathrm{O}_{3}\right)$ with acetic anhydride $\left(\mathrm{C}_{4} \mathrm{H}_{6} \mathrm{O}_{3}\right)$ according to the following equation: $$\mathrm{C}_{7} \mathrm{H}_{6} \mathrm{O}_{3}+\mathrm{C}_{4} \mathrm{H}_{6} \mathrm{O}_{3} \longrightarrow \mathrm{C}_{9} \mathrm{H}_{8} \mathrm{O}_{4}+\mathrm{CH}_{3} \mathrm{CO}_{2} \mathrm{H}$$ (a) How many grams of acetic anhydride are needed to react with 4.50 g of salicylic acid? (b) How many grams of aspirin will result? (c) How many grams of acetic acid are formed as a byproduct?

Aspirin is prepared by reaction of salicylic acid $\left(\mathrm{C}_{7} \mathrm{H}_{6} \mathrm{O}_{3}\right)$ with acetic anhydride $\left(\mathrm{C}_{4} \mathrm{H}_{6} \mathrm{O}_{3}\right)$ according to the following equation:
$$\mathrm{C}_{7} \mathrm{H}_{6} \mathrm{O}_{3}+\mathrm{C}_{4} \mathrm{H}_{6} \mathrm{O}_{3} \longrightarrow \mathrm{C}_{9} \mathrm{H}_{8} \mathrm{O}_{4}+\mathrm{CH}_{3} \mathrm{CO}_{2} \mathrm{H}$$
(a) How many grams of acetic anhydride are needed to react with 4.50 g of salicylic acid?
(b) How many grams of aspirin will result?
(c) How many grams of acetic acid are formed as a byproduct?

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Key Concepts

Molar Mass Calculation

Calculating the molar mass of a compound involves summing the atomic masses of all the atoms in its molecular formula. This allows conversion between the mass of a substance and the number of moles, which is essential for quantitative chemical analysis.

Stoichiometric Calculations

Stoichiometric calculations involve converting between mass and moles using molar masses and applying mole ratios from the balanced chemical equation. This process is central to predicting the quantities of reactants required and products formed in a chemical reaction.

Balanced Chemical Equation

A balanced chemical equation is crucial because it provides the mole ratio in which reactants combine and products form. Understanding this concept allows one to correctly use the stoichiometric coefficients to relate the amounts of different substances involved in the reaction.

Mole Concept

The mole is a fundamental unit in chemistry that relates the mass of a substance to the number of particles it contains. It is used to bridge the gap between the microscopic world (individual molecules) and the macroscopic amounts of material measured in the laboratory.

Transcript

00:01 We're given to this reaction and asked to calculate the masses of the reactants and products based on an initial 4 .5 grams of salicyloc acid.

00:20 Now, in order to answer this, we're going to need the molar masses of each of these pieces.

00:32 In part a, we're asked how many grams of acetic and hydride are needed to find this.

00:39 First, we're going to start by changing the mass.

00:46 Of salicylic acid into moles of salicylic acid.

00:55 And to do that, we're going to divide by the molar mass.

00:59 So one mole of salicylic acid contains 138 .1 .12.

01:07 Grams of the same.

01:11 Notice at my units.

01:14 Cancel nicely.

01:15 And i find that this is equal to 0 .0 32580 moles.

01:33 And i'm going to use this value for parts a, b, and c.

01:39 So now starting with that many mole.

01:42 So you're just going to shorten it to 3, 2, 6.

01:56 But in my calculator, i'm going to use all the digits that i'm given.

02:02 So i see that there is a 1 to 1 ratio in my reaction, between salicylic acid and acetic and hydride.

02:11 So this is one mole, acetic and hydride, for every one mole of salicylic acid.

02:26 And then i'm going to finish by changing the moles to cell acetic and hydride to grams using its molar mass...

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