The Effect of 5 Drops of 0.1M Hydrochloric Acid (HCl) and Sodium Hydroxide (NaOH) on The pH Level of 5mL of Tap Water, Distilled Water, Commercial Buffer, and 10% Homogenized Potato Solution
Aya Ali
Ms. Kim
February, 29. 2016
SBI4U-04
Background / Pre-lab Questions:
Figure 1: Logarithmic pH scale (WHOI, 2016)
Almost all liquids that an individual encounters in their daily lives are classified as an acid or base, based on their hydrogen ion concentration relative to pure water, water that does not contain any salts and minerals and is chemically pure. An acid is a substance that donates hydrogen (H+) ions and contains a relatively higher H+ concentration than water, greater than 1 × 10 -7 M, while basic solutions accept hydrogen ions and have a lower H+ concentration, less than 1 × 10 -7 M (KA, 2016). The concentration of hydrogen ions in a substance is commonly measured by the ‘power of hydrogen’ (pH) scale, ranging levels from 0-14. The pH scale is a linear logarithmic scale resulting in values that increase or decrease by a factor of 10 each time. For instance, as seen in figure 1, the pH of 3 is 1000 times more acidic than the pH of 6. These values can be calculated as the negative log of a solution’s hydrogen ion concentration; pH = −log10 [H+]. The value of 7 on the pH scale is also known as neutral pH, meaning that the substance is neither acidic nor basic and contains a regulated amount of hydrogen ions (Senese, 2010). The
PH sensors are used in many scientific laboratories to measure the hydrogen-ion concentration of a liquid substance and to determine the basicity and acidity of a liquid. PH meters measure the electrical potential difference between a reference electrode probe and a pH electrode probe. Since these probes are very sensitive, they are required to be kept cleansed from contaminants. If exposed to contamination, one risks faulty or unreliable data, since their accuracy is dependent on a regular calibration and upkeep. To avoid this risk, and accurately measure hydrogen-ion concentration, the probes are kept in a buffer solution and calibrated before each use. [1]
The purpose of this experiment is to determine an unknown concentration of acid (hydrochloric acid) with a standard solution of a base (sodium carbonate) using titration method.
The Distilled water pH average of HCl for zero drops was 6.67, and the pH for the final thirtieth drop
The position of some of these hydrogen atoms formed change when the pH of a solution changes.
“The pH of a solution is a measure of the molar concentration of hydrogen ions in the solution and as such is a measure of the acidity or basicity (sic) of the solution. The letters pH stand for power of hydrogen and the numerical value defined as the negative base 10 logarithm of the molar concentration of hydrogen ions.” (PH, 2002). The pH scale is from 0 to 14. When the pH is higher, the hydrogen ions are fewer and the substance considered alkaline. This means when a pH unit increases by one, there is a tenfold change in the hydrogen ion. For example, if a substance has a 7 pH, it has 10 times as many as hydrogen ions available as 8 pH. A lake having a water pH between 6.5 and 8.5 is considered to be neutral. Researchers tested Peckham Park lake water monthly from August 2015 to April 2016 for water pH levels. A water quality PH test strip taken from a jar and dipped into the lake. After a few minutes, the strip will turn a color and this color determines the pH. The jar the strips came in has a chart of the colors on the back which compared to the color on the strip. The lake tested monthly using the PH test strips, which show the pH level, hardness, toxic, etc. using color-change
We only added a small amount of HCl to the water and sodium chloride. We did not continue to add more HCl after a significant drop in pH was recorded. We added a total of 2 mL of HCl to both H20 and NaCl before the pH changed. The 1 gram solution of sodium acetate and acetic acid changed after a 8 mL, and the other two never dropped before we reached our total of 10 mL HCl.
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).
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”.
Acids are a substance that has a pH less than 7. There are two different types of acid:
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;
In this experiment different pH levels ranging from 3 to 11 were used to test the effects on daphnia heart rate. The pH scale ranges from 0 to 14. A pH ranging from 0 to 6 is acidic, a pH of 7 is neutral, and a pH higher than 7 ranging from 8 to 14 is basic. PH revolves around hydrogen ions (H+). The reason pH levels can be acidic, basic, or neutral is because acids give hydrogen ions away while bases accept hydrogen ions. (Decelles, 2002).
My science fair topic will be measuring the acidic levels in different companies of water bottles such as Aquafina, Dasani, Evian, Fiji, Miami Dade Tap Water, Penta, Publix Spring Water, Smart Water, Smart Water, Volvic, Voss, and Zephyrhills. Bottled water has been tested for its ppm (parts per million) to measure the amount of particles inside the water. The pH scale is a measurement of how acidic or basic an aqueous solution is. The pH scale has a range of 0-14; numbers less than 7 are considered acidic and numbers greater than 7 are considered basic. An acidic pH level means that the solution has more free hydrogen ions, and a basic pH level means that the solution has more free hydroxyl ions. pH is reported in logarithmic units and an increase or decrease of one on the pH scale has a 10-fold change. The negative logarithmic of the hydrogen ion concentration calculates the pH level of a solution. This is why pH stands for the potential of hydrogen and it calculate din
Determination of Free Acidity and Total Acidity Reagents 1. Freshly prepared 0.01N oxalic acid solution for standardization of sodium hydroxide 2. Freshly prepared 0.01 N NaOH solution 3. Topfer's reagent: It is dimethyl amino benzene 0.5% in absolute ethanol 4. Freshly prepared 1% phenolphthalein solution Procedure 1.
Since the pH scale is based on pH values, ranging from 0 to 14, with 7.0 being of a neutral value of water, it is utilized to better classify basic and acidic solutions. When a pH is greater than 7.0, the solution is basic because of the concentration of hydrogen ions found in the solution. In addition, the solution also has acid an increase on a negative logarithmic scale. In contrast, if the solution is lower than 7.0 on the pH scale, it is acidic. Acidic solutions dissolve in water.
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.