Textbook Question
(a) Combustion analysis of 150.0 mg of 1,2,3,benzenetriol, a compound composed of carbon, hydrogen, and oxy-gen, gives 64.3 mg of H2O and 314.2 mg of CO2. What is the empirical formula of 1,2,3,benzenetriol?
Ch.3 - Mass Relationships in Chemical Reactions
Chapter 3, Problem 111
Compound X contains only carbon, hydrogen, nitrogen, and chlorine. When 1.00 g of X is dissolved in water and allowed to react with excess silver nitrate, AgNO3, all the chlorine in X reacts and 1.95 g of solid AgCl is formed. When 1.00 g of X undergoes complete combustion, 0.900 g of CO2 and 0.735 g of H2O are formed. What is the empirical formula of X?
Verified step by step guidance1
Step 1: Determine the amount of chlorine in the compound. The molar mass of AgCl is 143.32 g/mol. Use the mass of AgCl formed to calculate the moles of AgCl, which is equal to the moles of Cl in the compound since AgNO3 reacts with Cl in a 1:1 ratio.
Step 2: Convert the moles of Cl to grams using the molar mass of Cl (35.45 g/mol). This gives the mass of Cl in the 1.00 g of compound X.
Step 3: Determine the amount of carbon and hydrogen in the compound. The molar mass of CO2 is 44.01 g/mol and the molar mass of H2O is 18.02 g/mol. Use the masses of CO2 and H2O formed to calculate the moles of CO2 and H2O. The moles of C in the compound is equal to the moles of CO2 since each CO2 molecule contains one C atom. The moles of H in the compound is twice the moles of H2O since each H2O molecule contains two H atoms.
Step 4: Convert the moles of C and H to grams using their molar masses (C: 12.01 g/mol, H: 1.01 g/mol). This gives the masses of C and H in the 1.00 g of compound X.
Step 5: The mass of nitrogen in the compound can be found by subtracting the masses of C, H, and Cl from the total mass of the compound (1.00 g). Convert this mass to moles using the molar mass of N (14.01 g/mol).
Step 6: Now you have the moles of C, H, Cl, and N in the compound. Divide each of these by the smallest value to get the ratio of the atoms, which gives the empirical formula.
Verified video answer for a similar problem:
This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
7mWas this helpful?
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Stoichiometry
Stoichiometry is the branch of chemistry that deals with the quantitative relationships between the reactants and products in a chemical reaction. It allows chemists to calculate the amounts of substances consumed and produced in a reaction, based on balanced chemical equations. In this question, stoichiometry is essential for determining the moles of chlorine that reacted with silver nitrate and the moles of carbon and hydrogen produced during combustion.
Recommended video:
Guided course
01:16
Stoichiometry Concept
Empirical Formula
The empirical formula of a compound represents the simplest whole-number ratio of the elements present in that compound. It is derived from the mass of each element in a sample and is crucial for understanding the composition of the compound. In this question, calculating the empirical formula involves determining the moles of carbon, hydrogen, nitrogen, and chlorine from the experimental data provided.
Recommended video:
Guided course
02:26Empirical vs Molecular Formula
Combustion Analysis
Combustion analysis is a method used to determine the elemental composition of organic compounds by burning the sample and measuring the resulting products, typically carbon dioxide and water. The masses of these products are used to calculate the amounts of carbon and hydrogen in the original compound. In this question, the combustion of compound X provides critical data needed to find the empirical formula by allowing the calculation of the moles of carbon and hydrogen present.
Recommended video:
Guided course
01:29Combustion of Non-Hydrocarbons
Related Practice
Textbook Question
The molecular weight of ethylene glycol is 62.0689 when calculated using the atomic weights found in a standard periodic table, yet the molecular weight determined experimentally by high-resolution mass spectrometry is 62.0368. Explain the discrepancy.
Textbook Question
Assume that gasoline has the formula C8H18 and has a density of 0.703 g/mL. How many pounds of CO2 are produced from the complete combustion of 1.00 gal of gasoline?
Textbook Question
A pulverized rock sample believed to be pure calcium carbonate, CaCO3, is subjected to chemical analysis and found to contain 51.3% Ca, 7.7% C, and 41.0% O by mass. Why can't this rock sample be pure CaCO3?
Textbook Question
A certain alcoholic beverage contains only ethanol (C2H6O) and water. When a sample of this beverage undergoes com-bustion, the ethanol burns but the water simply evaporates and is collected along with the water produced by combus-tion. The combustion reaction is When a 10.00 g sample of this beverage is burned, 11.27 g of water is collected. What is the mass in grams of ethanol, and what is the mass of water in the original sample?
Textbook Question
A mixture of FeO and Fe2O3 with a mass of 10.0 g is con-verted to 7.43 g of pure Fe metal. What are the amounts in grams of FeO and Fe2O3 in the original sample?
1
views