Skip to main content
Pearson+ LogoPearson+ Logo
Ch.3 - Chemical Reactions and Reaction Stoichiometry
All textbooksBrown 14th EditionCh.3 - Chemical Reactions and Reaction StoichiometryProblem 58a
Chapter 3, Problem 58a

Propenoic acid, C3H4O2, is a reactive organic liquid that is used in the manufacturing of plastics, coatings, and adhesives. An unlabeled container is thought to contain this liquid. A 0.275-g sample of the liquid is combusted to produce 0.102 g of water and 0.374 g carbon dioxide. Is the unknown liquid propenoic acid? Support your reasoning with calculations.

Verified step by step guidance
1
Determine the moles of water and carbon dioxide produced from the combustion. Use the molar mass of water (18.02 g/mol) and carbon dioxide (44.01 g/mol) to convert the mass of each product to moles.
Calculate the moles of hydrogen and carbon in the original sample by using the stoichiometry of water and carbon dioxide. Each mole of water contains 2 moles of hydrogen, and each mole of carbon dioxide contains 1 mole of carbon.
Calculate the total mass of carbon and hydrogen in the sample from the moles determined in the previous step, using the atomic masses of carbon (12.01 g/mol) and hydrogen (1.008 g/mol).
Subtract the total mass of carbon and hydrogen from the original sample mass to estimate the mass of oxygen in the sample. Use the atomic mass of oxygen (16.00 g/mol) to find the moles of oxygen.
Compare the experimental mole ratio of carbon, hydrogen, and oxygen in the sample to the theoretical mole ratio in propenoic acid (C3H4O2). If the ratios are consistent, the unknown liquid is likely to be propenoic acid.

Recommended similar problem, with video answer:

Verified Solution

This video solution was recommended by our tutors as helpful for the problem above
Video duration:
6m
Was this helpful?

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Combustion Analysis

Combustion analysis is a technique used to determine the composition of organic compounds by burning them in excess oxygen. The products of combustion, typically carbon dioxide (CO2) and water (H2O), are measured to calculate the amounts of carbon and hydrogen in the original sample. This method is essential for identifying unknown organic compounds by comparing the experimental results with theoretical values.
Recommended video:
Guided course
01:29
Combustion of Non-Hydrocarbons

Molar Mass and Stoichiometry

Molar mass is the mass of one mole of a substance, expressed in grams per mole (g/mol). Stoichiometry involves using the relationships between reactants and products in a chemical reaction to calculate quantities. In this context, knowing the molar mass of propenoic acid allows for the conversion of the mass of combustion products into moles, which can then be compared to the expected ratios for propenoic acid.
Recommended video:
Guided course
02:11
Molar Mass Concept

Empirical Formula Determination

The empirical formula of a compound represents the simplest whole-number ratio of the elements present. To determine if the unknown liquid is propenoic acid, one must calculate the moles of carbon and hydrogen from the combustion products and then derive the empirical formula. This formula can be compared to the known formula of propenoic acid (C3H4O2) to confirm or refute the identity of the unknown liquid.
Recommended video:
Guided course
02:26
Empirical vs Molecular Formula
Related Practice
Textbook Question

(a) The characteristic odor of pineapple is due to ethyl butyrate, a compound containing carbon, hydrogen, and oxygen. Combustion of 2.78 mg of ethyl butyrate produces 6.32 mg of CO2 and 2.58 mg of H2O. What is the empirical formula of the compound?

3618
views
1
comments
Textbook Question

(b) Nicotine, a component of tobacco, is composed of C, H, and N. A 5.250-mg sample of nicotine was combusted, producing 14.242 mg of CO2 and 4.083 mg of H2O. What is the empirical formula for nicotine? If nicotine has a molar mass of 160 ± 5 g/mol, what is its molecular formula?

2292
views
Textbook Question

Valproic acid, used to treat seizures and bipolar disorder, is composed of C, H, and O. A 0.165-g sample is combusted to produce 0.166 g of water and 0.403 g of carbon dioxide. What is the empirical formula for valproic acid?

919
views
Textbook Question

Washing soda, a compound used to prepare hard water for washing laundry, is a hydrate, which means that a certain number of water molecules are included in the solid structure. Its formula can be written as Na2CO3 # xH2O, where x is the number of moles of H2O per mole of Na2CO3. When a 2.558-g sample of washing soda is heated at 125 C, all the water of hydration is lost, leaving 0.948 g of Na2CO3. What is the value of x?

2993
views
1
comments
Textbook Question

Epsom salts, a strong laxative used in veterinary medicine, is a hydrate, which means that a certain number of water molecules are included in the solid structure. The formula for Epsom salts can be written as MgSO4 # xH2O, where x indicates the number of moles of H2O per mole of MgSO4. When 5.061 g of this hydrate is heated to 250 C, all the water of hydration is lost, leaving 2.472 g of MgSO4. What is the value of x?

1350
views
Textbook Question

Hydrofluoric acid, HF(aq), cannot be stored in glass bottles because compounds called silicates in the glass are attacked by the HF(aq). Sodium silicate (Na2SiO3), for example, reacts as follows: Na2SiO3(s) + 8 HF(aq) → H2SiF6(aq) + 2 NaF(aq) + 3 H2O(l) (a) How many moles of HF are needed to react with 0.300 mol of Na2SiO3? (b) How many grams of NaF form when 0.500 mol of HF reacts with excess Na2SiO3? (c) How many grams of Na2SiO3 can react with 0.800 g of HF?

5329
views