1. ENGAGE PHASE
One day, a student drops in at the stall to get a drink. At the stall, she order orange juice and after
drank she noticed that the orange juice taste sour than usual. So, she wonders how concentration
of orange juice influences its taste and why mostly drink has different taste. She also thinks how
pH can lead to disease like cancer.
EMPOWER PHASE
Introduction
From our group discussion, we decided to choose experiment that test the pH level of common
drinks using the data logger. The pH data logger that we choose is DrDAQ data logger. DrDAQ
is used here as a pH meter with the addition of a pH probe to measure the pH level over the
entire pH scale of a range of common drinks. Recently dentists have begun warning about the
dangers of drinking acidic drinks. Teenagers, they suggest, who drink large amounts of fizzy
„pop‟ drinks suffer from tooth erosion whereby the enamel covering of the tooth is dissolved by
the acid in the drink. Athletes are also at risk from drinking sports drinks. The recommended
„safe‟ level for the pH of drinks is 5.5, Anything below this can promote tooth erosion. This
experiment looks at the relative pH values of different drinks and can be used to determine
whether a particular drink is „safe‟ according to the above criteria. It can also be used as a good
introduction to further studies into tooth decay and enamel stripping. It is suitable for ages 14+
and requires some knowledge of the pH measurement. Actually, measurement of pH for aqueous
solutions can be done with a glass electrode, pH meter or by using indicator. However, through
this experiment to test pH level in common drink, the method use to measure the level of pH is
by using pH meter by apply DrDAQ as a data logger.
All foods and drinks have their own pH levels which have risk to affect the pH of human body.
In chemistry, pH is a measure of the activity of the hydrogen ion. More clearly, pH is the
universally accepted scale for the concentration of hydrogen ions in an aqueous solution. A
common drinks pH can be measure either in acidic state, neutral or alkaline state. An ideal pH is
between seven to seven and half on the scale from one to 14. The human body can functions
optimally at alkaline conditions which is about at pH 7.4. It is necessary to maintain a healthy pH

2. level to make sure there is not too much acid interferes with our blood cells that have ability to
transport oxygen.
Drinking certain beverages also can increase our pH level. So that DrDAQ is used as a meter
with the addition of a pH probe to measure the pH level in the common drinks such as orange
juice and apple juice. Orange juice is one of the famous juices among the others in this world.
This is according to the Drink Secrets website. Recently, dentists have begun warning about the
dangers of drinking acidic drinks. Teenagers, they suggest, who drink large amounts of fizzy
„pop‟ drinks suffer from tooth erosion whereby the enamel that covering the tooth is dissolved by
the acid in the drink. Moreover, athletes also face the same problem and have to take risk
because they drinking sports drink.
This experiment looks at the relative pH values of different kinds and can be used to determine
whether a particular drink is safe according to the criteria that had been stated. Moreover, it is
also can be used as a good introduction to further studies into tooth decay and enamel stripping.
Furthermore, it is also introduction for using data logging that can operate independently of a
computer unlike many other types of data acquisition devices. Moreover, data loggers more
powerful programmable devices which are capable of handling hundreds of inputs.
A data logger is an attractive alternative to either a recorder or data acquisition system in many
applications. When compared to a recorder, data loggers have the ability to accept a greater
number of input channels, with better resolution and accuracy. Also, data loggers usually have
some form of on-board intelligence, which provides the user with diverse capabilities. For
example, raw data can be analyzed to give flow rates, differential temperatures, and other
interpreted data that otherwise would require manual analysis by the operator.
The major difference between a data logger and a recorder, however, is the way the data itself is
stored, analyzed and recorded. A common recorder accepts an input, and compares it to a full
scale value. The pen arm is then deflected across the recording width, to produce the appropriate
ratio of the actual input to the full scale input. For example, using a recorder with a 1 Volt full
scale, an input of 0.5 Volts would move the pen 0.5/1 or 50% of the distance across the recording
width. In comparison, a data logger accepts an input which is fed into an analog-to-digital
converter prior to analysis and storage. This method has advantages in accuracy and resolution,

3. while only a recorder can provide a truly continuous trend recording. Data loggers can also offer
advantages over dedicated, computer interface systems. A data logger is a self contained unit,
which does not require a host to operate. It can be installed in almost any location, and left to
operate unattended. Data loggers have a distinct advantage over conventional interface devices,
in that they operate in this stand-alone mode, and yet have the capability to “dump” or transfer
the data to a host system, if required. Most data loggers have the ability to work similarly to
standard recorders, in that they provide the user with a hard copy printout of the data recorded.
This data can be immediately analyzed for trends, or stored for historical archive purposes. Data
loggers can also monitor for alarm conditions, while recording a minimum number of samples,
for economy. If the recording is of a stead-state nature, without rapid changes, the user may go
through rolls of paper, without seeing a single change in the input. A data logger can record at
very long intervals, saving paper, and can note when an alarm condition is occurring. When this
happens, the event will be recorded and any outputs will be activated, even if the event occurs in
between sample times. A record of all significant conditions and events is generated using a
minimum of recording hardcopy.
The differences between various data loggers are based on the way that data is recorded and
stored. The basic difference between the two data logger types is that one type allows the data to
be stored in a memory, to be retrieved at a later time, while the other type automatically records
the data on paper, for immediate viewing and analysis. Many data loggers combine these two
functions, usually unequally, with the emphasis on either the ability to transfer the data or to
provide a printout of it. The example of data loggers are temperature, flow and level, pH and
conductivity, data acquisition, pressure, strain and force, and heaters. Each data logger can be
use in many experiments such as air velocity indicators, doppler flowmeters, level measurement,
magnetic flowmeters, environmental instrumentation, pH electrodes and instruments, water and
soil analysis instrumentation.
Equipment required

4. 1. DrDAQ data logger connected to a PC
2. One pH sensor (DrDAQ Part no DD011)
3. Containers for the drinks (we used plastic drinking cups)
4. A selection of common drinks - we used:
a) Orange Juice
b) Apple Juice
c) Black Coffee
d) Black Tea
e) Lemon Tea
f) Original Coke
g) Pepsi
h) Cherry Coke
i) Ribena
j) Lemon Squash
k) Milk
Experiment set up
1. Fill all cups with an equal amount of liquid which will cover the pH probe tip.
2. Mark the cups so that they can be identified later.
3. Plug the pH probe into DrDAQ and run PicoLog software.
4. Optionally, you can calibrate the pH probe using buffer solutions.
5. It is important to allow all the drinks to stabilise at room temperature since pH readings
vary with temperature.

5. Diagram showing the experiment set up
Carrying out the experiment
Here is a table showing the pH of some common substances for reference.
Before starting the experiment, make a table listing drinks that you will test and indicate what
you expect the pH of each drink to be.

6. Create your table as shown below:
Gently agitate the pH probe in each liquid for a minute or two while the pH reading settles
then record the reading in the table and move onto the next liquid. NOTE Take care to
thoroughly clean the pH probe in a large container of water between each liquid to reduce
cross contamination of the liquids.
When you have tested all your available drinks, plot the results on a bar graph with each bar
showing the expected value and recorded value for each liquid.
Result
Drinks pH
Apple juice 3.49
Orange juice 3.84
Black tea 6.37
Black coffee 5.51
Questions and discussion of results
The formula for pH is:
Q1. With respect to the results you have obtained, can you make any predictions about the likely
pH values of the foods and drinks we consume ?
In chemistry, pH is a measure of the activity of the hydrogen ion. Pure water has a pH very close
to 7 at 25°C. Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater

7. than 7 are basic or alkaline. With respect to the results we have obtained, we can predict that the
pH of the majority tested drinks are acidic and neutral.
Q2. Find the pH of a solution whose is 9.5E-8M
Based from the question number 2, when the concentration of hydrogen ion, [H+] is 9.5x10-8 M,
the pH value is,
pH = - log [H+]
= - log (9.5 x 10-8 M)
= 7.02
Q3. Calculate the of a solution with a pH of 5.45
From question number 3, a solution with a pH of 5.45 has the concentration of hydrogen of 3.5 x
10-6 M. The calculation is as follow:
pH = - log [H+]
[H+] = anti -log (-5.45)
= 3.5 x 10-6 M
Q4. How does the pH reading of a liquid vary with temperature? (possibly heat a buffer
solution)
Let's begin with the words acidic and basic as extremes which describe solutions as hot and
cold are extremes which describe temperature. Just as mixing hot and cold water evens out
the temperature, mixing acids and bases can cancel their extreme effects and is then
considered neutral. pH is a scale that is used to measure a substance's acidity. pH scale can
tell if a liquid is more acid or more base, just as the Fahrenheit or Celsius scale is used to

8. measure temperature. The range of the pH scale is from 0 to 14 from very acidic to very
basic. A pH of 7 is neutral. A pH less than 7 is acidic and greater than 7 is basic. Each whole
pH value below 7 is ten times more acidic than the next higher value. For example, a pH of 4
is ten times more acidic than a pH of 5 and a hundred times (10 X 10) more acidic than a pH
of 6. This holds true for pH values above 7, each of which is ten times more basic (also
called alkaline) than the next lower whole value. An example would be, a pH of 10 is ten
times more alkaline than a pH of 9.
While an absolutely accurate measurement of pH levels requires advanced equipment, a
rough measurement can be made with pH test strips. An acid-base indicator is a weak acid or
a weak base. A staple of chemistry labs all around the world, these inexpensive strips are
simply dipped into the liquid whose pH level is being gauged. After a short while, the color
of the strip will change, and the final color is then compared to the rainbowlike color palette
on the package, where each shade is assigned a pH number. Darker colors usually mean a
high pH value, while lighter colors indicate low pH levels. Indicators have a very useful
property - they change color depending on the pH of the solution they are in. This color
change is not at a fixed pH, but rather, it occurs gradually over a range of pH values. This
range is termed the color change interval. Each pH indicator is defined by a useful pH range.

9. For example Phenolphthalein changes from colorless at 8.0 to pink at 10.0. And Bromthymol
Blue has a useful range from 6.0 (yellow) to 7.6 (blue).
Temperature will have a measurable yet very slight effect on the pH of water. In fact, pure
water has a pH of exactly 7 only at 25 degrees Celsius, or 77 degrees Fahrenheit. As the
water temperature goes up, pH goes down. The converse is also true, in that colder water has
a higher pH value. At 60 degrees Celsius (140 degrees Fahrenheit), pure water will register a
pH value of 6.96. In other words, the change is very slight and cannot be registered with
crude measurement techniques such as pH test strips. The reason temperature affects water's
pH is that water molecules tend to break down into their constituents, hydrogen and oxygen,
as the temperature increases. As temperatures increase, a larger proportion of water
molecules break up, producing more hydrogen, which then increase the pH of the water.
ENHANCE PHASE
According to the problem statements in engaging phase, the students tasted his oranges
juice to be sourer than it should be. He was doubt on how the concentrations of the juice affect
the taste and why the tastes of various drinks are different. He also thinks why pH leads to
diseases such as cancer. Basically, the tastes are due to the pH value. Technically, the pH of a
solution depends on measuring concentration. The pH value in acidic range for the high
concentration of solution is lower than the pH value for the solution that is high in concentration.
High concentration solution has high concentration of H+. The concentration of H+ leads the
value of pH. For example, the concentrations of 0.02 M of solution have low pH than the 0.05 M
solution. The concentration of the juice is maybe higher than usual. The taste for the acidic is
sour. Besides that, various drinks have different tastes because pH values of the drinks are
different. Some of the drinks are sour because it is acidic and the others are bitter because it is
basic or alkaline. There are also neutral drinks with pH 7.

10. Consumption of many acidic foods can lead to severe diseases such as cancer because
acidic conditions inhibit nerve action in our human body. That is why we should balance our diet
as it helps to maintain the pH balance of the blood. When we consume more acidic food, our
blood will develop a more acidic condition. Then the body will inevitably deposit the excess acid
to another area of the body so that the blood will be able to maintain an alkaline condition. As
this cycle continues, these areas will increase in acidity and some cells will die. The dead cells
will then turn into acids. Some cells may adapt and instead of dying as normal cells do in an acid
environment, they will survive by becoming abnormal. These abnormal cells are known as
malignant cells. Malignant cells do not correspond with brain function or with our DNA memory
code. Malignant cells grow indefinitely and without order. This malignant cell is known as
cancer.

11. Bibliography
1) http://www.ehow.co.uk/info_8465063_acidity-level-orange-juice.html
2) http://www.livestrong.com/ph-in-drinking-water/
3) http://www.livestrong.com/article/485450-what-drink-will-increase-the-ph-level-of-my-
body/