Skip to main content
Ch.3 - Molecules and Compounds
Chapter 3, Problem 123

A compound of molar mass 177 g/mol contains only carbon, hydrogen, bromine, and oxygen. Analysis reveals that the compound contains eight times as much carbon as hydrogen by mass. Find the molecular formula.

Verified Solution

Video duration:
4m
This video solution was recommended by our tutors as helpful for the problem above.
Was this helpful?

Key Concepts

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

Molar Mass

Molar mass is the mass of one mole of a substance, typically expressed in grams per mole (g/mol). It is calculated by summing the atomic masses of all the atoms in a molecule. Understanding molar mass is crucial for determining the number of moles in a given mass of a compound, which is essential for stoichiometric calculations in chemistry.
Recommended video:
Guided course
02:11
Molar Mass Concept

Mass Ratio

The mass ratio is a comparison of the mass of one element to the mass of another element in a compound. In this question, the mass ratio indicates that the mass of carbon is eight times that of hydrogen. This relationship allows us to set up equations to find the relative amounts of each element in the compound, which is vital for deriving the molecular formula.
Recommended video:
Guided course
02:14
Neutron-Proton Ratio

Empirical and Molecular Formulas

The empirical formula represents the simplest whole-number ratio of the elements in a compound, while the molecular formula shows the actual number of atoms of each element in a molecule. To find the molecular formula, one often starts with the empirical formula and uses the molar mass to determine the actual number of atoms. This distinction is important for accurately describing the composition of the compound in question.
Recommended video:
Guided course
02:26
Empirical vs Molecular Formula
Related Practice
Textbook Question

Combustion analysis of a 13.42-g sample of equilin (which contains only carbon, hydrogen, and oxygen) produces 39.61 g CO2 and 9.01 g H2O. The molar mass of equilin is 268.34 g/mol. Find its molecular formula.

3137
views
Textbook Question

Estrone, which contains only carbon, hydrogen, and oxygen, is a female sexual hormone in the urine of pregnant women. Combustion analysis of a 1.893-g sample of estrone produces 5.545 g of CO2 and 1.388 g H2O. The molar mass of estrone is 270.36 g/mol. Find its molecular formula.

1481
views
1
rank
Textbook Question

A hydrate of copper(II) chloride has the following formula: CuCl2 • x H2O. The water in a 3.41-g sample of the hydrate is driven off by heating. The remaining sample has a mass of 2.69 g. Find the number of waters of hydration (x) in the hydrate.

3681
views
Textbook Question

Researchers obtained the following data from experiments to find the molecular formula of benzocaine, a local anesthetic, which contains only carbon, hydrogen, nitrogen, and oxygen. Complete combustion of a 3.54-g sample of benzocaine with excess O2 forms 8.49 g of CO2 and 2.14 g H2O. Another 2.35-g sample contains 0.199 g of N. The molar mass of benzocaine is 165 g/mol. Find the molar formula of benzocaine.

1228
views
1
rank
Textbook Question

Find the total number of atoms in a sample of cocaine hydrochloride, C17H22ClNO4, of mass 23.5 mg.

1226
views
1
rank
Textbook Question

Vanadium forms four different oxides in which the percent by mass of vanadium is, respectively, (a) 76%, (b) 68%, (c) 61%, and (d) 56%. Determine the formula and the name of each oxide.

1103
views