The purpose of this lab practice is to identify the pH of certain solutions and if they are acids or bases. Introduction: In chemistry, pH is a measure of the activity of the (solvated) hydrogen ion. p[H], which measures the hydrogen ion concentration, is closely related to, and is often written as, pH. Depending on the pH solutions will be acids or bases. An acid is a chemical compound that dissociates in solution, releasing hydrogen ions and lowering the solution pH (a proton donor).
An acidic solution has a pH below 7. Acids can be strong acids which ionize completely in aqueous solution or weak acids which ionize partially. A base is a substance that combines with acids to form salts; a substance that dissociates to give hydroxide ions in aqueous solutions; a substance whose molecule or ion can combine with a proton (hydrogen ion); a substance capable of donating a pair of electrons (to an acid) for the formation of a coordinate covalent bond. Bases can be strong bases which are able to dissociate completely in water or weak bases which dissociate partially.
In this practice we use natural indicators, which are pH indicators in the form of plant pigments known as antocyanines which change color over different pH ranges and depending on source for the pH. Neutralization is a chemical reaction in which a base and an acid react to form a salt. Materials: DroppersHidrion paperred cabbage indicatorMilkBleachYogurt Microplate| VinegarEasy OffMg (OH) WaterMuriatic acidBeakersDetergent S/M| Methods: 1. Open the dropper, put the ph strip inside the bottle, analyze the pH of the substance according to this table: . Put 5 drops on the microplate of each of the substances and 3 drops of the natural indicators and watch the change in the color. Results: | Hidrion Paper| Red cabbage indicator| Substance| Color| pH| Color| pH| Detergent S/M| | 9| GreenishBlue| 8-9| Yogurt| | 4| ReddishViolet| 5-6| Milk| | 7| Violet| 7| Water| | 7| Violet| 7| Mg(OH)| | 10| Greenish blue| 8-9| Muriatic acid| | 1| Red| 1-2| Easy Off| | 12| Blue| 10-11| Vinegar| | 1| Red| 1-2| Bleach| | 14| Yellow| 12-14| Analysis: The red cabbage is less reliable than the hidrion paper.
The Essay on Liter Of Solution Base Acid Solutions
Introduction: In 1909 S. P. L. Sorensen published a paper in Biochem Z in which he discussed the effect of H 1+ ions on the activity of enzymes. In the paper he invented the term pH to describe this effect and defined it as the -log[H 1+ ]. In 1924 Sorensen realized that the pH of a solution is a function of the 'activity' of the H 1+ ion not the concentration and published a second paper on the ...
Conclusions: Depending on the pH of the substance the hidrion paper will show certain colors and the change in color of the red cabbage also depends on the pH of the substance. Complementary task: 1. Explain what is and indicator A compound which changes color depending on the pH of the solution of which it is a part. 2. How are indicators produced? From plant extracts. 3. Mention 3 examples of acid-base indicators, including the range of pH at which they work and the observed colors. Use the following chart: Indicator| Color| pH Range| | Acid| Base| |
Methyl Red| Yellow| Red| 4. 8-6. 0| Bromothymol Blue| Yellow| Blue| 6. 0-7. 6| Phenol Red| Yellow| Red| 6. 8-8. 4| 4. Investigate the real pH of the substances used in practice. Indicate if the substance is an acid, a base or if it is neutral. Final reflection: Knowing if a substance is an acid or a base is very important to prevent accidents of skins corrosion due to acids and to avoid mixing substances that may cause a lower pH. Acids and bases are present everyday since we eat yogurt for breakfast until we wash our clothes before going to sleep.
