Biology: Chemistry in Biology: 11: pH - Medical Animation
MEDICAL ANIMATION TRANSCRIPT: Now that we've discussed acids and bases, let's talk about pH. The H in pH stands for hydrogen. pH is a measure of the concentration of free hydrogen ions in a solution. It tells us whether the solute in a solution is an acid or a base. Sometimes a base is referred to as being alkaline. To measure how acidic or basic a substance is, scientists use the pH scale, numbered from 1 to 14. The pH scale is an inverse scale of the concentration of hydrogen ions in a solution. The more hydrogen ions it contains, the lower its pH number and the stronger an acid it is. In contrast, the more hydroxide ions a solution has, the higher its pH number and the more basic or alkaline it is. Water is pH-neutral because it contains equal numbers of hydrogen and hydroxide ions. So water is right in the middle of the scale at a neutral pH of seven. Each whole number on the pH scale represents an exponential difference in value. This means that each whole number decrease in pH represents a 10 times increase in hydrogen ion concentration. For example, coffee has a pH of 5. So from a pH of 7 to a pH of 5, there is 10x10 or a 100-fold increase in hydrogen ion concentration compared to neutral water. As you can see, coffee is 100 times more acidic than water. This also means that coffee is 100 times less alkaline than water because it has a 100-fold decrease in hydroxide ion concentration. Baking soda is an example of a base with a pH of nine. It has a 100-fold decrease in hydrogen ion concentration compared to neutral water. However, it also has a 100 fold increase in hydroxide ion concentration. So baking soda is a hundred times more basic or alkaline than water. To function properly, biological processes in the human body require fluids with a pH in the range of approximately 6.5 to 7.5. For example, the normal pH of blood is 7.4. If acids or bases in the blood lower or raise the pH too much, a person could become sick or die. One way the body controls pH is through the use of different buffers. Buffers are substances that neutralize other acids and bases in solutions such as blood to prevent dramatic swings in pH. In summary, pH is a measure of the concentration of free hydrogen ions in a solution. A pH scale is an inverse scale of hydrogen ion concentration from 1 to 14. If the hydrogen ion and hydroxide ion concentrations are the same, the solution is pH-neutral. A pH of seven on the pH scale is neutral. Pure water has a pH of seven. Acids have a pH of less than seven and bases have a pH of greater than seven. The closer to seven a solution is, the weaker the acid or base. The farther away from seven a solution is, the stronger the acid or base. A buffer is a weak acid or base that reacts with a strong acid or base to prevent large changes in pH.
"Our firm was able to settle our case at an all day mediation yesterday and
I am confident that the detail and overall appearance of the medical
illustrations significantly contributed to the settlement. When we require
medical illustrations in the future, I will be sure to contact [MLA]."
Noel Turner, III
Burts, Turner, Rhodes & Thompson
"You and your company are wonderful. Your service, turnaround time, quality
and price were better than I could have asked for. Please add me to your
long list of satisfied customers."
Robert F. Linton, Jr.
Linton & Hirshman
"I wanted to thank you for the terrific job you did illustrating my client's
injuries. The case was settled at the pre-suit mediation, and I believe a
good part of the success we had was due to the medical legal art you
Your work received the ultimate compliment at the conclusion of the mediation. The hospital risk manager took the exhibit with them at the
conclusion of mediation, and will be using it to train nurses on how to
prevent bed sores..."
Steven G. Koeppel Troy, Yeslow & Koeppel, P.A. Fort Myers, FL
"We are extremely pleased with the quality of the medical exhibits and the
timely manner in which they were provided. I will certainly recommend
your company to my business associates who could benefit from your services.
Please tell Brian Wilson [Director of Content Development, Senior Medical
Illustrator] that he did an exceptional job on these exhibits."
Medical Legal Art creates medical demonstrative evidence (medical
illustrations, drawings, pictures, graphics, charts, medical animations,
anatomical models, and interactive presentations) for use during legal
proceedings, including research, demand letters, client conferences,
depositions, arbitrations, mediations, settlement conferences, mock jury
trials and for use in the courtroom. We do not provide legal or medical
advice. If you have legal questions, you should find a lawyer with whom you
can discuss your case issues. If you have medical questions, you should seek the advice of a healthcare provider.