Table of contents

1. Matter and Measurements4h 31m
2. Atoms and the Periodic Table5h 23m
3. Ionic Compounds2h 18m
4. Molecular Compounds2h 18m
5. Classification & Balancing of Chemical Reactions3h 17m
6. Chemical Reactions & Quantities2h 27m
7. Energy, Rate and Equilibrium3h 46m
8. Gases, Liquids and Solids3h 25m
9. Solutions4h 10m
10. Acids and Bases3h 29m
11. Nuclear Chemistry56m
BONUS: Lab Techniques and Procedures1h 38m
BONUS: Mathematical Operations and Functions47m
12. Introduction to Organic Chemistry1h 34m
13. Alkenes, Alkynes, and Aromatic Compounds2h 12m
14. Compounds with Oxygen or Sulfur1h 6m
15. Aldehydes and Ketones1h 1m
16. Carboxylic Acids and Their Derivatives1h 11m
17. Amines39m
18. Amino Acids and Proteins1h 51m
19. Enzymes1h 37m
20. Carbohydrates1h 41m
21. The Generation of Biochemical Energy2h 8m
22. Carbohydrate Metabolism2h 22m
23. Lipids2h 26m
24. Lipid Metabolism1h 45m
25. Protein and Amino Acid Metabolism1h 37m
26. Nucleic Acids and Protein Synthesis2h 54m

6. Chemical Reactions & Quantities

Mole Concept

GOB Chemistry

6. Chemical Reactions & Quantities

Mole Concept

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1:58 minutes

Problem 114c

Textbook Question

Ammonium sulfate, (NH₄)₂SO₄, is used in fertilizers to provide nitrogen for the soil.
c. How many moles of ammonium sulfate contain 7.4 × 10²⁵ atoms of N?

Verified step by step guidance

Step 1: Begin by identifying the chemical formula of ammonium sulfate, (NH₄)₂SO₄. This compound contains two ammonium ions (NH₄⁺), each of which has one nitrogen atom. Therefore, there are 2 nitrogen atoms per formula unit of ammonium sulfate.

Step 2: Determine the relationship between the number of nitrogen atoms and the number of ammonium sulfate formula units. Since each formula unit contains 2 nitrogen atoms, the total number of nitrogen atoms is twice the number of formula units.

Step 3: Use Avogadro's number (6.022 × 10²³ atoms/mol) to relate the number of formula units to moles. Divide the given number of nitrogen atoms (7.4 × 10²⁵ atoms) by 2 to find the number of ammonium sulfate formula units, and then divide this result by Avogadro's number to convert formula units to moles.

Step 4: Write the mathematical expression for the calculation: \[ \text{Moles of ammonium sulfate} = \frac{\text{Number of nitrogen atoms}}{2 \times 6.022 \times 10^{23}} \].

Step 5: Perform the calculation using the provided values to determine the number of moles of ammonium sulfate. Ensure units are consistent throughout the calculation.

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Key Concepts

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

Moles and Avogadro's Number

A mole is a unit in chemistry that represents 6.022 x 10²³ entities, such as atoms or molecules. This number, known as Avogadro's number, allows chemists to convert between the mass of a substance and the number of particles it contains. Understanding moles is essential for calculating the number of moles from a given number of atoms.

Chemical Composition of Ammonium Sulfate

Ammonium sulfate, (NH₄)₂SO₄, consists of two ammonium ions (NH₄⁺) and one sulfate ion (SO₄²⁻). Each ammonium ion contains one nitrogen atom, meaning that one formula unit of ammonium sulfate contains two nitrogen atoms. Knowing the chemical composition is crucial for determining how many moles of ammonium sulfate correspond to a specific number of nitrogen atoms.

Stoichiometry

Stoichiometry is the branch of chemistry that deals with the quantitative relationships between the reactants and products in a chemical reaction. It allows for the calculation of the amounts of substances involved based on their chemical formulas. In this context, stoichiometry helps in determining how many moles of ammonium sulfate are needed to yield a certain number of nitrogen atoms.