Introduction
The purpose of our lab is to find the red cabbage pH indicator; you must know the acids and bases of the solution to find the indicator. Anthocyanin pigments in red cabbage can be used to determine the pH of a solution based on the color it changes to. In order to determine the pH indicator for the red cabbage you must find the pH values of those solutions from the liquid dyes, also known as the pH indicators.
Literature Review
Acids and Bases
Acids and Bases can be very similar. Acids, when mixed with water free hydrogen ions. Bases, when mixed with water free hydroxide ions. In both cases, Acids and bases, the freeing of ions is called dissociation. Although there can be rich solutions and poor solutions. Acidic is a solution that is very rich in
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hydrogen ions. Hydrogen ions with a poor solution would be called a basic solution. There are some strong acids and some weak. The difference between the two is that strong acids dissociate completely freeing large amounts of hydrogen ions and weak acids dissociate in part of it, therefore making it weak. Bases are the same way they have some strong bases and some weak bases. By identifying the acids and bases of this experiment it will help determine the pH indicator. PH What is pH?
PH stands for the power of hydrogen. It is also a numeric scale mainly used in chemistry to specify acidity or basicity of a solution. In a solution pH measures the concentration of hydrogen ions. The pH concentration can have many orders of magnitude, meaning it is roughly the negative of the logarithm of base ten of the concentration. In this experiment it indicates the acids and bases of the solution being tested. A color pH key determines whether the pH is more acidic or more basic depending on the number. For example, the number seven would be neutral. If the concentration of hydrogen ions increases the pH of the solution produced would be less than seven, therefore it would be considered more acidic. The same goes for the concentration of hydrogen ions when they decrease, the pH solution produced would become more than seven and therefore it being considered a basic solution. To sum it up, the lower the pH value is the stronger the acid is and the higher the concentration of ions is in the solution. When pH is used it is usually used to compare acids. When trying to find the pH indicator for the experiment it will be used to find the acids and bases of the solution in the
experiment. Anthocyanin Anthocyanin is a blue, violet, or red flavonoid pigment found in plants. Plants such as radishes, beets, and blueberries all have anthocyanin in them and so do red cabbages. To determine the color of the anthocyanin the numbers of the removable protons that are still attached to the molecule. Anthocyanin is a weak acid. An anthocyanin with two protons, it means it would have two protons to donate and would reflect a red light. If an anthocyanin had no more protons to donate, it would reflect a greenish-yellow light. If an anthocyanin only had one proton to donate it would reflect blue light. The solution the anthocyanin is placed in depends on the hydrogen ion concentration and the number of protons donated. If it is placed in a solution with low ion concentration, it will donate more protons. The solution will have a combination of the three molecules with two protons, one proton, or no protons, and will reach equilibrium, if the ion concentration of the solution is not particularly high or low. The anthocyanins cause the cabbage’s color to change based on the alkalinity or acidity of the solution it is placed in.
For acid into water, the pH level dropped drastically, from 6 to 3. For base into water, the pH increased from 6 to 12. During the buffer experiments, the pH level stayed the same during the whole experiment for acid and base. It stayed at a pH of 12, hence the name “Buffer
to digest starch. I am going to vary the PH from PH6 to PH9 to see
The strong acid used in the experiment was hydrochloric acid. Using different types of acid would mean different ions present in solution. This means that there will be different sized ions, meaning that there will be space for different numbers of water molecule. Only using the hydrochloric acid would allow for consistent hydration, as all the ions would be the same size and would provide the same number of molecules to hydrate them. Another controlled variable was the volume of water used. This allows the same number of water molecules available to hydrate the ions in the acid solution. It also means that there will be the same mass of water available to conduct the heat energy released from
Most substances fall on a scale ranging from the most acidic to the the most basic with neutral substances falling somewhere in the middle. Scientists call this the pH scale. pH levels are measured in numbers,0 to 14. The closer a substance is to zero the more acidic it would be. The closer to 14 the more basic a substance would be.Now what defines an acid and a base, one might ask? There are three ways of defining acids, each singling out a specific property. The first theory is the Arrhenius Theory with states, that an acid is a substance that produces the ion H+ when in a water solution, while a base is a substance which produces the ion OH- when in a water solution. Examples of an Arrhenius acid are HCl and HNO3. Examples of an Arrhenius base are NaOH and AlOH3.
I decided to experiment with pHs within the range pH 2 to pH7, as I
Base being Baking Soda, or Sodium Bicarbonate, and the acid being Vinegar, or Acetic Acid for a control. I measured 10 ml. of Vinegar, dumped that into a two inch high glass jar, and wrote down the pH level. Then I measured o...
strong acid or base does not necessarily yield a drastic jump in pH. The acid
The simplest experiment for this type of situation would be to use red and blue litmus paper to distinguish between acids, bases and salts. Hydrochloric acid (HCl) makes blue litmus paper change color going from blue to red, making it an acid. Sodium hydroxide (NaOH) makes red litmus paper change color going from red to blue, making it a base. Sodium chloride solution (NaCl) is neutral, since it would only soak blue and red litmus paper, considering that it is a by product of when an acid and a base mix together, neutralizing each other.
The pH of the analyte, in this case a strong acid like HCl, is plotted against the volume of the strong base, NaOH, that is being added. The titration of a strong acid with a strong base produces a titration curve as above.
The point was signaled by a change in color of an indicator that had been added to the acid solution. Indicator is a substance that has distinctly different colors in acidic and basic media. Phenolphthalein was a common indicator which was colorless in acidic and neutral solutions, but reddish pink was result in basic solutions. Strong acid (containing H+ ion) and strong base ( containing OH ) were 100% ionized in water and they were all strong electrolytes.
It changes from blue to red with acids but loses its colour in the presence of certain chemicals, one of which is vitamin C. DCPIP solution can be used to test for the presence of vitamin C in foods. Hypothesis Orange juice has the highest content of vitamin C. Citrus fruits have a higher content of vitamin C. The orange and lemon juice contain more vitamin C than the pineapple juice. Furthermore, as lemons are more acidic than oranges, I predict that the orange juice will contain more vitamin C than the lemon juice. Vitamin C affects, the ph the more vitamin C the higher the ph. Variables Independent Variables Different fruit juices (Pineapple, orange and lemon).
Acid-Base balance is the state of equilibrium between proton donors and proton acceptors in the buffering system of the blood that is maintained at approximately pH 7.35 to 7.45 under normal conditions in arterial blood. It is important to regulate chemical balance or homeostasis of body fluids. Acidity or alkalinity has to be regulated. An acid is a substance that lets out hydrogen ions in solution. Strong acid like hydrochloric acid release all or nearly all their hydrogen ions and weak acids like carbonic acid release some hydrogen ions.
Titration is a technological process in which a solution, known as a titrant, is slowly and carefully added from a burrette into a fixed volume of another solution (known as the sample). In an acid-base titration an acid neutralizes a base or vice versa. This process is maintained untill the reaction between the titrant and the sample (acid and the base) is judged to be complete. The reaction is judged to be complete when the endpoint is reached. An endpoint in a titration analysis is referred to as the point at which no more titrant is added due to an observable colour change of an indicator. Indicators can be used to find an endpoint because they change colour when the pH of a solution changes and an endpoint in a titration is an empirical approximation of the equivalence point, which is the point of major pH change in the titration sample due to the fact that equal chemical amounts of reactants have been combined at that point. All indicators have a pH range, which is the range of pH values at which the colour of the indicator changes. Thus
An alkali is a soluble base and forms hydroxyl ions (OH-) when placed in water. It can be called a proton acceptor and will accept hydrogen ions to form H2O. An example of an alkali is Sodium Hydroxide (NaOH). Neutralization Reaction:- [IMAGE]Acid + Alkali Salt + Water [IMAGE]Hydrochloric acid + Sodium Hydroxide Sodium Chloride + Water [IMAGE]HCl(aq) + NaOH(aq) NaCl(aq) + H2O(l) [IMAGE]H+ (aq) +
Advocates of alkaline water believe that it can neutralize the acid in your bloodstream and help your body metabolize nutrients more effectively. The word “alkaline” in alkaline water refers to its pH level. Acidity is something that’s