/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 23 Calculate the molecular mass or ... [FREE SOLUTION] | 91影视

91影视

Log out

Learning Materials

Features

Discover

Chapter 3: Problem 23

Calculate the molecular mass or formula mass (in amu) of each of the following substances: (a) \(\mathrm{CH}_{4}\), (b) \(\mathrm{NO}_{2},\) (c) \(\mathrm{SO}_{3},\) (d) \(\mathrm{C}_{6} \mathrm{H}_{6}\), (e) NaI, (f) \(\mathrm{K}_{2} \mathrm{SO}_{4}\), (g) \(\mathrm{Ca}_{3}\left(\mathrm{PO}_{4}\right)_{2}\).

Short Answer

Expert verified
(a) 16 amu, (b) 46 amu, (c) 80 amu, (d) 78 amu, (e) 150 amu, (f) 174 amu, (g) 310 amu.

Step by step solution

01

Understand the Atomic Masses

Each element in the periodic table has a specific atomic mass in atomic mass units (amu), denoted as follows: H (hydrogen) is approximately 1 amu, C (carbon) is 12 amu, N (nitrogen) is 14 amu, O (oxygen) is 16 amu, Na (sodium) is 23 amu, I (iodine) is 127 amu, K (potassium) is 39 amu, S (sulfur) is 32 amu, P (phosphorus) is 31 amu, and Ca (calcium) is 40 amu.
02

Calculate Molecular Mass of CH鈧�

In methane (CH鈧�), the formula contains 1 carbon atom and 4 hydrogen atoms. Calculate the molecular mass: \( 1 \times 12 + 4 \times 1 = 16 \text{ amu} \).
03

Calculate Molecular Mass of NO鈧�

In nitrogen dioxide (NO鈧�), the formula contains 1 nitrogen atom and 2 oxygen atoms. Calculate the molecular mass: \( 1 \times 14 + 2 \times 16 = 46 \text{ amu} \).
04

Calculate Molecular Mass of SO鈧�

In sulfur trioxide (SO鈧�), the formula has 1 sulfur atom and 3 oxygen atoms. Calculate the molecular mass: \( 1 \times 32 + 3 \times 16 = 80 \text{ amu} \).
05

Calculate Molecular Mass of C鈧咹鈧�

Benzene (C鈧咹鈧�) has 6 carbon atoms and 6 hydrogen atoms. The molecular mass is: \( 6 \times 12 + 6 \times 1 = 78 \text{ amu} \).
06

Calculate Molecular Mass of NaI

For sodium iodide (NaI), there is 1 sodium atom and 1 iodine atom. The formula mass is: \( 1 \times 23 + 1 \times 127 = 150 \text{ amu} \).
07

Calculate Molecular Mass of K鈧係O鈧�

Potassium sulfate (K鈧係O鈧�) includes 2 potassium atoms, 1 sulfur atom, and 4 oxygen atoms. Calculate the molecular mass: \( 2 \times 39 + 1 \times 32 + 4 \times 16 = 174 \text{ amu} \).
08

Calculate Molecular Mass of Ca鈧�(PO鈧�)鈧�

In calcium phosphate (Ca鈧�(PO鈧�)鈧�), there are 3 calcium atoms, 2 phosphorus atoms, and 8 oxygen atoms. Calculate the molecular mass: \( 3 \times 40 + 2 \times 31 + 8 \times 16 = 310 \text{ amu} \).

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Over 30 million students worldwide already upgrade their learning with 91影视!

Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Atomic Mass
Atomic mass is a key concept in chemistry that refers to the mass of an atom of an element. It's usually expressed in atomic mass units (amu). Knowing the atomic mass allows us to calculate the mass of a molecule or compound by summing the atomic masses of its component atoms.
The atomic mass of an element can be found on the periodic table and is often close to the mass number, which is the total number of protons and neutrons in an atom. For example:
  • Hydrogen (H) has an atomic mass of about 1 amu.
  • Carbon (C) has an atomic mass of 12 amu.
  • Sulfur (S) has an atomic mass of 32 amu.
Thus, understanding atomic mass is foundational to grasping how molecular masses are determined and compared.
Molecular Formula
A molecular formula shows the exact number and type of atoms present in a molecule of a compound. It is a concise way to represent information about the atoms that constitute a particular chemical substance.
For instance, the molecular formula of methane is \( ext{CH}_4\) which indicates one carbon atom and four hydrogen atoms per molecule.
Molecular formulas are like the recipe for a compound, giving detailed guidance on its composition. With this information, you can calculate the molecular mass by adding up the atomic masses of all atoms indicated in the formula.
Chemical Compounds
Chemical compounds are substances formed when two or more different types of atoms bind together. They have unique properties that are different from the elements that make them up. Understanding chemical compounds is vital for studying reactions, properties, and various processes in chemistry.
Let's take water ( H_2O o), a simple compound made of two hydrogen atoms and one oxygen atom. This composition gives water distinct properties like its liquid state at room temperature.
  • Methane ( CH_4 o): A compound of carbon and hydrogen.
  • Benzene ( C_6H_6 o): A compound forming a hexagonal ring of carbon atoms.
  • Calcium phosphate ( Ca_3(PO_4)_2 o): Contains calcium, phosphorus, and oxygen.
Compounds are everywhere and comprise the materials and substances we observe in our everyday life.
Periodic Table Elements
The periodic table is a foundational tool in chemistry that organizes elements based on their properties. Each element is represented by a symbol and has associated properties, such as atomic number and atomic mass. This organization helps chemists easily access and communicate essential data about elements.
For instance, the position of an element can show its reactivity, the group it belongs to, and even the types of chemical bonds it can form. Important periodic table elements when calculating molecular masses include:
  • Carbon (C), Atomic number: 6
  • Nitrogen (N), Atomic number: 7
  • Oxygen (O), Atomic number: 8
The table not only categorizes regular elements but also the rare and synthetic ones, offering a comprehensive overview of matter as we know it.

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

On what law is stoichiometry based? Why is it essential to use balanced equations in solving stoichiometric problems?

A mixture of methane \(\left(\mathrm{CH}_{4}\right)\) and ethane \(\left(\mathrm{C}_{2} \mathrm{H}_{6}\right)\) of mass \(13.43 \mathrm{~g}\) is completely burned in oxygen. If the total mass of \(\mathrm{CO}_{2}\) and \(\mathrm{H}_{2} \mathrm{O}\) produced is \(64.84 \mathrm{~g},\) calculate the fraction of \(\mathrm{CH}_{4}\) in the mixture.

(a) A research chemist used a mass spectrometer to study the two isotopes of an element. Over time, she recorded a number of mass spectra of these isotopes. On analysis, she noticed that the ratio of the taller peak (the more abundant isotope) to the shorter peak (the less abundant isotope) gradually increased with time. Assuming that the mass spectrometer was functioning normally, what do you think was causing this change? (b) Mass spectrometry can be used to identify the formulas of molecules having small molecular masses. To illustrate this point, identify the molecule which most likely accounts for the observation of a peak in a mass spectrum at: 16 amu, \(17 \mathrm{amu}, 18 \mathrm{amu},\) and 64 amu. (c) Note that there are (among others) two likely molecules that would give rise to a peak at 44 amu, namely, \(\mathrm{C}_{3} \mathrm{H}_{8}\) and \(\mathrm{CO}_{2} .\) In such cases, a chemist might try to look for other pea generated when some of the molecules break apart in the spectrometer. For example, if a chemist sees a peak at 44 amu and also one at 15 amu, which molecule is producing the 44 amu peak? Why? (d) Using the following precise atomic masses: \({ }^{1} \mathrm{H}(1.00797 \mathrm{amu}),{ }^{12} \mathrm{C}(12.00000 \mathrm{amu}),\) and \({ }^{16} \mathrm{O}(15.99491 \mathrm{amu}),\) how precisely must the masses of \(\mathrm{C}_{3} \mathrm{H}_{8}\) and \(\mathrm{CO}_{2}\) be measured to distinguish between them? (e) Every year millions of dollars' worth of gold is stolen. In most cases the gold is melted down and shipped abroad. This way the gold retains its value while losing all means of identification. Gold is a highly unreactive metal that exists in nature in the uncombined form. During the mineralization of gold, that is, the formation of gold nuggets from microscopic gold particles, various elements such as cadmium (Cd), lead (Pb), and zinc (Zn) are incorporated into the nuggets. The amounts and types of the impurities or trace elements in gold vary according to the location where it was mined. Based on this knowledge, describe how you would identify the source of a piece of gold suspected of being stolen from Fort Knox, the federal gold depository.

Consider the reaction $$ \mathrm{MnO}_{2}+4 \mathrm{HCl} \longrightarrow \mathrm{MnCl}_{2}+\mathrm{Cl}_{2}+2 \mathrm{H}_{2} \mathrm{O} $$ If 0.86 mole of \(\mathrm{MnO}_{2}\) and \(48.2 \mathrm{~g}\) of \(\mathrm{HCl}\) react, which reagent will be used up first? How many grams of \(\mathrm{Cl}_{2}\) will be produced?

Carbon has two stable isotopes, \({ }_{6}^{12} \mathrm{C}\) and \({ }_{6}^{13} \mathrm{C},\) and fluorine has only one stable isotope, \({ }_{9}^{19} \mathrm{~F}\). How many peaks would you observe in the mass spectrum of the positive ion of \(\mathrm{CF}_{4}^{+}\) ? Assume that the ion does not break up into smaller fragments.
See all solutions

Recommended explanations on Chemistry Textbooks

Kinetics

Read Explanation

Inorganic Chemistry

Read Explanation

Making Measurements

Read Explanation

Ionic and Molecular Compounds

Read Explanation

Organic Chemistry

Read Explanation

Chemical Analysis

Read Explanation
View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.