PreparED Study Materials
CHEM 127: General Chemistry 1
School: Houston Community College System
Number of Notes and Study Guides Available: 4
Notes
Videos
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
Chromium & Oxygen: Limiting Reactants & Chromium(III) Oxide Formation
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Unravel the reaction of chromium and oxygen forming chromium(III) oxide. Examine different scenarios to determine the limiting reactant using stoichiometric ratios. Understand how to predict product amounts through these calculations.
Calculate oxygen molar concentration in water at 25°C with a partial p
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This video explores molar concentration (molarity) and demonstrates the calculation of oxygen's molar concentration in water at 25°C, considering a partial pressure of 0.22 atm by employing Henry's Law and the given Henry's Law constant for oxygen, revealing that under these conditions, there are 2.86 x 10?? moles of oxygen per liter of water, highlighting the significance of understanding these concepts for managing gas dissolution in liquids across varying circumstances.
Electronegativity & Acid Strength: Decoding Acid Formulas
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This video discusses how the electronegativity of attached groups affects the strength of acids. Comparing pairs such as Chloroacetic vs Fluoroacetic and Acetic vs Nitroacetic acids, we highlight which is the stronger acid in each pair and why.
Molecular Geometries Explained: From N?O to PF? - Shape and Structure
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Discover the distinct geometries of molecules like N?O, SO?, H?S, and PF?. Unravel the difference between molecular and electron shapes. Master the basics of linear, bent, tetrahedral, and trigonal pyramidal structures.
Does Cesium Bromide & Hydrogen Iodide in Water Conduct Electricity?
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Explore the conductivity of aqueous solutions: Cesium bromide and hydrogen iodide. Understand their ionic nature and how it leads to the presence of charged ions enabling electricity conduction





