Skip to main content
Ch.3 - Molecules and Compounds
Tro - Chemistry: A Molecular Approach 5th Edition
Tro5th EditionChemistry: A Molecular ApproachISBN: 9780134874371Not the one you use?Change textbook
All textbooksTro 5th EditionCh.3 - Molecules and CompoundsProblem 64c
Chapter 3, Problem 64c

Determine the number of moles (of molecules or formula units) in each sample. c. 0.1187 g C8H18

Verified step by step guidance
1
Identify the molecular formula of the compound, which is \( C_8H_{18} \).
Calculate the molar mass of \( C_8H_{18} \) by adding the atomic masses of all the atoms in the formula. Carbon (C) has an atomic mass of approximately 12.01 g/mol, and hydrogen (H) has an atomic mass of approximately 1.01 g/mol.
Multiply the number of each type of atom by its atomic mass and sum these values to find the molar mass of \( C_8H_{18} \).
Use the formula: \( \text{moles} = \frac{\text{mass (g)}}{\text{molar mass (g/mol)}} \) to calculate the number of moles of \( C_8H_{18} \) in the sample.
Substitute the given mass (0.1187 g) and the calculated molar mass into the formula to find the number of moles.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
1m
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. For example, to find the molar mass of octane (C8H18), you would multiply the number of carbon atoms by the atomic mass of carbon and the number of hydrogen atoms by the atomic mass of hydrogen, then add these values together.
Recommended video:
Guided course
02:11
Molar Mass Concept

Moles

A mole is a unit in chemistry that represents 6.022 x 10^23 entities, such as atoms, molecules, or formula units. This number, known as Avogadro's number, allows chemists to count particles by weighing them. The concept of moles is fundamental for converting between mass and the number of particles in a sample, facilitating stoichiometric calculations in chemical reactions.
Recommended video:
Guided course
01:25
Mole Concept

Conversion from Mass to Moles

To determine the number of moles from a given mass of a substance, you can use the formula: moles = mass (g) / molar mass (g/mol). This calculation allows you to convert the mass of a sample into the number of moles, which is essential for understanding the quantity of reactants or products in chemical reactions. In the case of 0.1187 g of C8H18, you would first calculate its molar mass and then apply this formula.
Recommended video:
Guided course
02:28
Mass and Moles Conversion
Related Practice
Textbook Question

How many molecules are in each sample? a. 6.5 g H2O c. 22.1 g O2 d. 19.3 g C8H10

1
views
Textbook Question

Determine the number of moles (of molecules or formula units) in each sample. a. 55.98 g CF2Cl2

1
views
Textbook Question

Calculate the formula mass for each compound. a. MgBr2 b. HNO2 c. CBr4 d. Ca(NO3)2

Textbook Question

Determine the number of moles (of molecules or formula units) in each sample. d. 195 kg CaO

Textbook Question

Determine the number of moles (of molecules or formula units) in each sample. b. 23.6 kg Fe(NO3)2

1
views
Textbook Question

How many molecules (or formula units) are in each sample? a. 85.26 g CCl4 b. 55.93 kg NaHCO3 c. 119.78 g C4H10 d. 4.59×105 g Na3PO4

1
views