Investigating the relationship between temperature and equilibrium constant in weak acids
Topic/Purpose The topic of the investigation is equilibria of weak acids, using ethanoic acid. The purpose of the investigation is to determine the relationship between temperature and the equilibrium/dissociation constant of weak acids, by calculating the K_a value of ethanoic acid at various temperatures.
Aim
The aim of the investigation is to determine whether the relationship between temperature and the equilibrium constant is linear or exponential by measuring the pH of a weak acid at various temperatures ranging from 20 ˚C to 80 ˚C. This will be achieved by deducing the K_a values for the acid, and plotting them on a graph against temperature.
…show more content…
Weak acids do not fully dissociate in a solution, releasing only some of their hydrogen atoms, and an equilibrium is formed when they react. Ethanoic acid is an organic compound and has a pH of 2.9, is a component of vinegar, and has anti-bacterial properties. However, it also has negative properties since it can inhibit carbohydrate metabolism, leading to the demise of the organism. Figure 1. Molecular structure of ethanoic acid pH is a measure of how acidic or alkaline a solution is, and it is measured using a scale ranging from 0 to 14, 0-6 being acidic, 8-14 basic and 7 neutral. However, if a solution is a very strong alkali or very strong acid, its pH value can be outside of the scale. pH is also a measure of hydrogen ions (H^+) in the solution. According to the Arrhenius definition an acid forms hydrogen ions in an aqueous solution. However, the Bronsted-Lowry theory suggests that an acid is a substance which can act as proton donor. Finally, the Lewis theory states that an acid is a lone pair of electrons acceptor (to form a dative covalent bond). Acids also have the ability to turn blue litmus red and form salts when they react with bases and certain metals. Weak acids normally have pH values ranging from 2 to
The reaction "ICE" table demonstrates the method used in order to find the equilibrium concentrations of each species. The values that come directly from the experimental procedure are found in the shaded regions. From these values, the remainder of the table can be completed.
The purpose of this semester long experiment was to determine an unknown organic acid. An organic acid is an organic compound with acidic properties. A base reacts with acids to form salts. Titrations are used to determine the concentration of unknown substances. The purpose of the KHP experiment was to determine the molarity of NaOH. HCl titrations are mainly to check technique and used to verify the molarity of NaOH solution. The hypothesis is that this acid is C4H3OCOOH.
will have a pH between 1 and 6 and the weak bases between 8 and 14. The exact order of weak acids and weak bases is determined by comparing the ionization constants (Ka for the weak acids and Kb for the
To start out this study the difference between acids and bases has to be identified. Acids have very low pHs and have a high concentration of hydronium ions, while bases have a high pH and have a high concentration of hydroxide ions. The difference between strong bases and acids, and weak bases and acids is the amount of dissociation. Strong bases and acids dissociate a large amount and let go of their ions in solution, while weak bases and acids may only let go of some of their ions. This is important because if the unknown solutions aren’t strong acids or bases then using their ions to calculate the pH of the solutions will give false results (Diffen 2012).
The purpose of this experiment was to determine the pKa, Ka, and molar mass of an unknown acid (#14). The pKa was found to be 3.88, the Ka was found to be 1.318 x 10 -4, and the molar mass was found to be 171.9 g/mol.
pH is also known as a measure of hydrogen ions in a solution. A hydrogen ion is the nucleus of a hydrogen atom being split from its electron. Studying the pH of different types of soil being placed in a control group such as tap water will represent the acidity or alkalinity of the matter. The pH scale begins at 0 and goes all the way up to 14, pH 7 being its neutral point, which isn’t acidic or basic. A neutral point on the acidic scale is in the middle, anything lower than the neutral point (7), is acidic, and anything higher than the neutral point is considered basic or “alkaline”.
The freezing point constant (Kf) of water is 1.86 °C m-1. Each mass amount and Van’t Hoff factor was calculated then analyzed in a table.
Acids are a corrosive substance with a pH less than 7. Acidity is caused by a high concentration of hydrogen ions.
When using different methods to measure pH levels there are some tools that can be useful. Some more than others but by putting into action the different methods it may determine which tools will work best and give the best results when testing the pH within a solution. The pH, which stands for the proportion of hydrogen ions in a solution, could be acidic (acidosis), neutral or basic (alkaline). The pH scale goes from numbers 1 through 14. A pH of 7 is neutral;
Fluorene's range was 100.5 C - 114.7 C. The range of the acid was 121.2 C - 143.4 C.
Ka is the acid dissociation constant and [HA] is the concentration of the weak acid . Strong acids usually completely dissociate and has a Ka value greater than 1. Weak acids don’t dissociate completely and have a Ka value much smaller than 1. pKa values are often used for weak acids due to being able to work with whole numbers
To prepare and purify an ester: 1-pentyl ethanoate, using pent-1-ol and ethanoic acid. An annotated reaction showing this reaction is shown below:
The pH of a solution is the measure of the concentration of charged Hydrogen ions in that given solution. A solution with a pH lower than seven is considered to be acidic. A solution with a higher pH is a base. It is very important for organisms to maintain a stable pH. Biological molecules such as proteins function only at a certain pH level and any changes in pH can result in them not functioning properly. To maintain these constant pH levels, buffer solutions are used. A buffer solution can resist change to small additions of acids or base’s. A good buffer will have components that act like a base, and components that act like an acid.
The hydrogen ion (H+) concentration is extremely important to living organisms. Even small changes in H+ ¬¬ion concentration can cause serious consequences to the structural and functional integrity of molecules. Consequently, it is important to regulate the pH within strict limits so that important biochemical processes of living systems can proceed normally.
What are the effects of different temperatures on the decomposition of Hydrogen Peroxide with the Enzyme Catalase. Different enzymes work best at different optimal temperatures, and with this experiment we hope to discover which temperatures are unideal for Catalase. The substrate is H2O2 which binds to the active site of the enzyme Catalase. The reaction in question is as written below: