The Relationship Between the Measured Concentration and Molecule Count to the pH of a Solution

The objective of the experiments is to test the pH of various solutions, including water, coffee, milk, soda, drain cleaner, orange juice, and hand soap. Other than testing the pH, the experiment also evaluates the concentration, the concentration of OH-, the molecules count, molecules count of and the molecule count of OH-. The experiment also seeks to establish the relationship between the measured concentration and molecule count to the pH of a solution.  Begin with water and recorded the measured pH, concentration of hydroxonium ion, the concentration of hydroxide ions, OH-, molecule count of water, molecule count of and the molecule count of 0H- ions. The concentration of ions will be estimated in moles per liter. Repeat step 2 for six more solutions (not including water). 

For the selected solutions, record the pH, concentration of hydroxonium ion, the concentration of hydroxide ions, OH-, molecule count of water, molecule count of and the molecule count of 0H- ions for concentrated and dilute solution. 

The pH scale is a measure of whether a substance is acidic or basic. The range of the pH scale is from 0 to 14, such that the median, 7, represents neutral. Any pH above 7 is basic, while a pH below 7 is acidic ( USGS, 2021). The acidity or alkalinity of a solution is determined by the amount of hydrogen and hydroxyl ions. Acidic solutions contain more hydrogen ions, while alkaline solutions contain more hydroxyl ions. The pH of a solution is measured using logarithmic units that calculate the number of times that a solution is more concentrated than water. A pH of 6, for example, means that a solution is ten times more acidic than pure water, which is neutral. Similarly, a pH of 5 means that a solution is ten times more acidic relative to the solution with a pH of 6. Contrary, a pH of above 7 implies that a solution is ten times more basic relative to a solution with a pH below. A pH of 8, for example, implies that a solution is ten times more basic relative to pure water, which is neutral. The pH of water remained as seven regardless of the concentration. Coffee, milk, soda, and orange juice are acidic because their respective pH is less than the pH of pure water, 7. On the other hand, the pH of drain cleaner and hand soap are basic because the pH is above 7. The pH of a solution is determined by the concentration of hydroxonium and hydroxyl ions measured in mole per liter. The concentration of ions also determines the chemical properties of a solution and the possible reactions ( USGS, 2021) . When a solution is neutral, it means that the number of moles of the hydroxonium ions is equal to the moles of the hydroxonium ion. The pH of a solution is expressed as the logarithm to base 10 of the concentration of hydroxonium ions in moles per liter.

As shown, the concentration of in moles per liter of water is 1.0* meaning that the pH of water is equal to 7. Similarly concentration of in moles per liter of drained cleaner is   1.0* translating to a pH of 13. The recorded pH of drained cleaner is, however, 12.69. When expressed as a logarithmic function, the concentration of ions, therefore, estimate pH to a whole number. Similarly, the pH can be expressed using the concentration of hydroxide ions pOH = -log [OH-] ( Lumen Learning, 2021). For example, the concentration of OH- ions in moles per liter of water is 1.0* 

Consequently, the pOH of water = -log [OH-] = -log (10-7) = +7 

The pH of dilute and concentrated water = 14-pOH = 14-7 = 7 

Similarly, the concentration of OH- ions in moles per liter of concentrated hand soap is 1.0*  

The pOH of hand = -log [OH-] = -log (10-4) = +4 

The pH of concentrated hand soap = 14 - pOH = 14 – 4 = 10 

Also, t he concentration of OH- ions in moles per liter of concentrated coffee is 1.0*  

The pOH of hand = -log [OH-] = -log (10-9) = +9 

The pH of concentrated coffee = 14 - pOH = 14 – 9 = 5 

Neutral solutions had equal molecules of and OH- ions. Contrary, acidic solutions had more molecules of ions relative to the OH- ions while basic solutions had less ions relative to the OH-ions. Similarly, the concentration of in moles per liter was more than OH- ions in acidic solutions and vice versa. A higher concentration of basic or acidic ions is directly correlated with the number of molecules. When the concentration of ions in moles per liter is higher, the number of molecules increase, causing the pH to decline. Similarly, when the concentration of OH- ions in moles per liter is high, the number of molecules increases, causing the pH to increase. 

The general trend suggests that the concentration of acidic and basic solutions differ for dilute and concentrated solutions. Although the concentration of ions remain the same for dilute and concentrated coffee, soda, and orange juice. The OH- ions were less in the dilute solution making the concentrated solutions more acidic than the dilute solutions. The OH- ions remained the same for the dilute and concentrated drain cleaner, and hand soap remained the same, although the ions were a little higher for the dilute solutions causing the pH of the dilute solutions to be slightly less basic. Dilute milk had a higher concentration of OH- ions but remained slightly less acidic as compared to concentrated milk. In conclusion, the experiment provided an intense learning experience on pH. Initially, I thought milk was neutral, but the experiment showed that both dilute and concentrated milk are slightly acidic. 

References 

Lumen Learning. (2021).  PH and poh | Chemistry . Lumen Learning – Simple Book Production.  https://courses.lumenlearning.com/wsu-sandbox2/chapter/ph-and-poh/ 

USGS. (2021).  PH scale . USGS.gov | Science for a changing world.  https://www.usgs.gov/media/images/ph-scale-0#:~:text=pH%20is%20a%20measure%20of,hydroxyl%20ions%20in%20the%20water