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

1. Matter and Measurements

Significant Figures (Simplified)

GOB Chemistry

1. Matter and Measurements

Significant Figures (Simplified)

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1:59 minutes

Problem 20b

Textbook Question

Identify the exact number(s), if any, in each of the following pairs of numbers:
b. 6 nickels and 16 g of nickel

Verified step by step guidance

Step 1: Understand the concept of exact numbers. Exact numbers are values that are counted or defined, not measured. They have no uncertainty and are considered to have an infinite number of significant figures.

Step 2: Analyze the first number, '6 nickels.' Since this is a count of physical objects (nickels), it is an exact number because counting is not subject to measurement uncertainty.

Step 3: Analyze the second number, '16 g of nickel.' This is a measured quantity, as it involves the mass of nickel determined using a measuring device. Measured quantities are not exact numbers because they have a degree of uncertainty associated with the measurement.

Step 4: Conclude that '6 nickels' is an exact number, while '16 g of nickel' is a measured number.

Step 5: Remember that exact numbers are often used in calculations without affecting the number of significant figures, whereas measured numbers require attention to significant figures and uncertainty.

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Key Concepts

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

Units of Measurement

Understanding units of measurement is crucial for comparing quantities. In this question, 'nickels' refers to a count of coins, while 'grams' (g) is a metric unit for mass. Recognizing the difference between these units helps in determining if the quantities can be directly compared or if conversion is necessary.

Nickel as a Material

Nickel is a chemical element and a metal commonly used in coinage. In this context, the question involves both the number of nickel coins (nickels) and the weight of nickel in grams. Knowing that a nickel coin is primarily composed of nickel allows for a better understanding of the relationship between the number of coins and their total mass.

Conversion Between Mass and Quantity

To effectively analyze the question, one must understand how to convert between the mass of a material and the quantity of items made from that material. For example, knowing the weight of a single nickel (approximately 5 grams) allows for the calculation of the total mass of 6 nickels, facilitating a comparison with the 16 grams of nickel.