PreparED Study Materials
CHEM 211: General Chemistry
School: Northern Illinois University
Number of Notes and Study Guides Available: 15
Notes
Study Guides
Videos
Breaking Down Mixtures: Finding Mass Percent of Sodium Compounds
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Uncover the method to determine mass percentages of Sodium Bromide and Sodium Sulfate in a mixture using the given Sodium content. Walk through a step-by-step calculation leveraging molar masses to derive the composition. Discover the resulting mass percentages: 23.85% for Sodium Bromide and 76.15% for Sodium Sulfate
Lattice Energy: Always Positive; Hydration Energy: Always Negative
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In this video we clarify why lattice energy in solids is always a positive value due to the energy needed to separate ions making it an endothermic process. On the flip side hydration energy is always negative as it releases heat when ions dissolve in water making it an exothermic reaction. We use sodium chloride as a real-world example to illustrate these crucial thermodynamic concepts
Hypothesis to Theory: The Evolution of Scientific Understanding
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Delve into the journey of scientific ideas as we discuss how a hypothesis can evolve into a theory, and whether a theory can ever become a law. Uncover the distinctions and connections between these fundamental elements of scientific understanding in this illuminating video.
Analyzing Molecular Structure Levels in DNA, tRNA, and mRNA
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This video explores the concept of structural levels (primary, secondary, tertiary, and quaternary) in biomolecules, focusing on double-stranded DNA, tRNA, and mRNA to understand the diverse ways these molecules exhibit these structural layers.
Calculating Percent Composition: Using Molecular Formulas & Atomic Mas
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Understand the process of calculating percent composition using the molecular formula. Grasp the methodology with compounds like C2H4O2, CH2O2, and more. Discover how atomic masses influence the mass percent of elements in various compounds.
Kettle Scale Removal: Water Filling Calculation
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Learn a practical application of chemistry and mathematics in your daily life. Whether you're a tea or coffee enthusiast, this video offers valuable insights into scale removal and maintaining your kitchen appliances.






