CHEM 140: Introductory Chemistry

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.

This video delves into the significance of electron configurations in understanding an atom's chemical behavior. It examines and corrects inaccuracies in the electron configurations of Aluminium (Al), Boron (B), and Fluorine (F). For instance, the electron configuration for Aluminium is initially presented with an incorrect number of electrons in the 2p subshell, stressing the importance of adhering to the rules of electron configuration for precise atomic representation.

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

Understanding pH Values: In this video we break down the pH levels of various solutions. Discover the importance of acid strengths via Ka and pKa contrast weak vs. strong acids and learn the counterintuitive relationship between pOH and pH.

This instructional video demonstrates the process of calculating the mass percent of various solutions, using the formula "mass of solute divided by mass of solution, all multiplied by 100%." It provides step-by-step calculations for three different solutions, revealing the concentration of each solute in terms of mass percent, offering a practical understanding of quantifying solute proportions in solutions.

In this video, we demonstrate the creation of Lewis structures for methane, carbon dioxide, hydrogen selenide, and ammonia, highlighting the arrangement of atoms and bonds in each molecule. The video emphasizes the importance of Lewis structures in visualizing atomic bonding and the presence of lone electron pairs.