Textbook Question
A sample that weighs 107.75 g is a mixture of 30% helium atoms and 70% krypton atoms. How many particles are present in the sample?
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Ch.3 - Mass Relationships in Chemical Reactions
McMurry8th EditionChemistryISBN: 9781292336145
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Table of contents
- Ch.1 - Chemical Tools: Experimentation & Measurement143
- Ch.2 - Atoms, Molecules & Ions134
- Ch.3 - Mass Relationships in Chemical Reactions149
- Ch.4 - Reactions in Aqueous Solution157
- Ch.5 - Periodicity & Electronic Structure of Atoms92
- Ch.6 - Ionic Compounds: Periodic Trends and Bonding Theory73
- Ch.7 - Covalent Bonding and Electron-Dot Structures47
- Ch.8 - Covalent Compounds: Bonding Theories and Molecular Structure51
- Ch.9 - Thermochemistry: Chemical Energy104
- Ch.10 - Gases: Their Properties & Behavior138
- Ch.11 - Liquids & Phase Changes43
- Ch.12 - Solids and Solid-State Materials56
- Ch.13 - Solutions & Their Properties98
- Ch.14 - Chemical Kinetics79
- Ch.15 - Chemical Equilibrium107
- Ch.16 - Aqueous Equilibria: Acids & Bases94
- Ch.17 - Applications of Aqueous Equilibria125
- Ch.18 - Thermodynamics: Entropy, Free Energy & Equilibrium66
- Ch.19 - Electrochemistry130
- Ch.20 - Nuclear Chemistry73
- Ch.21 - Transition Elements and Coordination Chemistry122
- Ch.22 - The Main Group Elements155
- Ch.23 - Organic and Biological Chemistry43
Chapter 3, Problem 57c
What is the mass in grams of each of the following samples? (c) 0.0015 mol of diazepam (Valium), C16H13ClN2O
Verified step by step guidance1
Determine the molar mass of diazepam (C_{16}H_{13}ClN_{2}O) by adding the atomic masses of all the atoms in the molecular formula.
Calculate the molar mass: (16 \(\times\) \(\text{atomic mass of C}\)) + (13 \(\times\) \(\text{atomic mass of H}\)) + (1 \(\times\) \(\text{atomic mass of Cl}\)) + (2 \(\times\) \(\text{atomic mass of N}\)) + (1 \(\times\) \(\text{atomic mass of O}\)).
Use the formula: \(\text{mass}\) = \(\text{moles}\) \(\times\) \(\text{molar mass}\) to find the mass in grams.
Substitute the given number of moles (0.0015 mol) and the calculated molar mass into the formula.
Perform the multiplication to find the mass in grams of the diazepam sample.
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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, the molar mass of diazepam (C16H13ClN2O) can be determined by adding the atomic masses of carbon, hydrogen, chlorine, nitrogen, and oxygen in the molecular formula.
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Molar Mass Concept
Mole Concept
The mole is a fundamental unit in chemistry that quantifies the amount of substance. One mole contains Avogadro's number of entities, approximately 6.022 x 10^23. This concept allows chemists to convert between the number of particles (atoms, molecules) and the mass of a substance, facilitating calculations in stoichiometry and chemical reactions.
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Conversion between Moles and Grams
To convert moles of a substance to grams, the formula used is: mass (g) = number of moles × molar mass (g/mol). This relationship is essential for determining the mass of a sample when the number of moles is known, as in the case of calculating the mass of 0.0015 mol of diazepam using its molar mass.
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Related Practice
Textbook Question
Iron metal can be produced from the mineral hematite, Fe2O3, by reaction with carbon. How many kilograms of iron are present in 105 kg of hematite?
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Textbook Question
The 'lead' in lead pencils is actually almost pure carbon, and the mass of a period mark made by a lead pencil is about 0.0001 g. How many carbon atoms are in the period?
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Textbook Question
An average cup of coffee contains about 125 mg of caffeine, C8H10N4O2. How many moles of caffeine are in a cup? How many molecules of caffeine?
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Textbook Question
What is the mass in grams of each of the following samples? (b) 0.0015 mol of lead
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Textbook Question
Titanium metal is obtained from the mineral rutile, TiO2. How many kilograms of rutile are needed to produce 100.0 kg of Ti?
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