Maslow’s Hierarchy of Needs

Figure 1. Maslow’s hierarchy of needs is illustrated here. In some versions of the pyramid, cognitive and aesthetic needs are also included between esteem and self-actualization. Others include another tier at the top of the pyramid for self-transcendence. Source: OpenStax Psychology 2e Maslow’s Hierarchy of Needs (OpenStax Psychology 2e) Abraham Maslow (1943) proposed a hierarchy of needs that spans the spectrum … Continue reading Maslow’s Hierarchy of Needs

pH and pOH

Figure 1. The pH and pOH scales represent concentrations of H3O+ and OH−, respectively. The pH and pOH values of some common substances at 25 °C are shown in this chart. Source: OpenStax Chemistry 2e OpenStax Chemistry 2e Hydronium and hydroxide ions are present both in pure water and in all aqueous solutions, and their concentrations are inversely … Continue reading pH and pOH

Brønsted-Lowry Acids and Bases

Source: OpenStax Chemistry 2e Bronsted-Lowry (OpenStax Chemistry 2e) The acid-base reaction class has been studied for quite some time. In 1680, Robert Boyle reported traits of acid solutions that included their ability to dissolve many substances, to change the colors of certain natural dyes, and to lose these traits after coming in contact with alkali (base) solutions. … Continue reading Brønsted-Lowry Acids and Bases

Equilibrium and Soft Drinks

Figure 1. Opening a soft-drink bottle lowers the CO2 pressure above the beverage, shifting the dissolution equilibrium and releasing dissolved CO2 from the beverage. (credit: modification of work by “D Coetzee”/Flickr) Equilibrium and Soft Drinks (OpenStax Chemistry 2e) The connection between chemistry and carbonated soft drinks goes back to 1767 when Joseph Priestley (1733–1804) developed a method of infusing … Continue reading Equilibrium and Soft Drinks

Equilibrium Constants

Figure 1. Changes in concentrations and Qc for a chemical equilibrium achieved beginning with (a) a mixture of reactants only and (b) products only. Source: OpenStax Chemistry 2e Equilibrium Constants (OpenStax Chemistry 2e) The status of a reversible reaction is conveniently assessed by evaluating its reaction quotient (Q). For a reversible reaction described by the reaction quotient is derived directly … Continue reading Equilibrium Constants

Chemical Equilibria

Figure 1. (a) A sealed tube containing colorless N2O4 darkens as it decomposes to yield brown NO2. (b) Changes in concentration over time as the decomposition reaction achieves equilibrium. (c) At equilibrium, the forward and reverse reaction rates are equal. Source: OpenStax Chemistry 2e Chemical Equilibria (OpenStax Chemistry 2e) The convention for writing chemical equations involves placing reactant … Continue reading Chemical Equilibria