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Orange Juices

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Group Four

on 20 August 2014

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Transcript of Orange Juices

Finding Viscosity using Poiseuille's Law
Chemistry- pH values and Citric Acid content
Biology - Finding Reducing Sugar Content of Orange Juice
Conclusion and Evaluation
What we did
Using Poiseuille's Law to calculate viscosity
Experimental Setup
Flow Rate of Orange Juice
We let the juice flow through the capillary tube and into collecting beaker for 5 minutes and measured the volume.
Other variables were also measured- height, density, radius and length of the tube
Poiseuille's Formula
Sources of Error
Suggestions for Improvement
What we did
Mixed glucose solutions of varying concentrations with Benedict's solution
Did the same with the juices
Heated it in boiling water, then let it cool
Put it into a colorimeter to find the absorption rate
Juice sprayed out the beaker when it was collected.
While measuring the radius of the capillary tube, the cross wires may not have been exactly tangential to the tube.
The pulp of each of the juices was removed due to the small capillary tube available.
Keep the apparatus at a smaller height off the table so that it is closer to the beaker to reduce spillage
Take more readings for each measurement to obtain a more accurate average and minimize errors in the readings.
Increasing order of Viscosity:
#1. Brand 2
#2. Brand 1
#3. Brand 3

Finding Citric Acid Content
What we did
Titration process
Titrant used was NaOH
Orange juice was diluted with water.
Phenolphthalein indicator mixed with the juice
Drops of NaOH was added to the juice solution till the end point was reached.
Setup of the Experiment
Reaching the End Point
What we did
Measuring Values
Misjudging the color of the indicator near the end point. Some people have different sensitivity to colors so they tend to misjudge the color at the end point.
Using the wrong amount of indicator (excess or inadequate).
Parallax error is possible while reading the volume on the burette.
Sources of Error
Keep the beaker on a white paper with a cross drawn to better notice color change and endpoint
Add titrant drop by drop, slowly
Read burette at eye level
More trials taken to reduce random error
Rinse the pipette and burette in the solution that is going to be used
Suggestions for Improvement
Investigation of Different Brands of Orange Juice
Sources of Error
The probe might not have been cleaned properly due to its shape.
The values kept changing constantly so it didn't fully stabilize.
There could have been water content on the pH probe due to improper cleaning.
Suggestions for Improvement
Cotton swabs can be used to wipe off droplets.
Longer time intervals for maximum stabilisation of the probe
Finding pH of the Orange Juices
Insert the pH probe into the juice.
pH probe is connected to a data logger and computer
Wait for the reading to stabilise to get the final pH value
Sources of error
Instead of measuring in milligrams we had measured in grams.
If we had measured in milligrams the possible sources of error are:
Parallax error while measuring Benedict's solution.
Chances are that some of the glucose could have dispersed due to the wind
The cuvette might not have been cleaned properly
Results of the two experiments are connected.
Brand 3 has high citric acid content and higher pH.
Brand 1 has the least of both.
Brand 2 is relatively moderate in both cases.
Setup of the Experiment for Qualitative Analysis
Suggestions for improvement
We could have used the centrifuge before immersing (the concentration of glucose with the Benedict's solution) into the hot water
Readings have to be made before sedimentation occurs
For more accuracy use a colorimeter with a wavelength of 670nm
By: Nandhini, Rithikha, Sidharth, Sowmya, Sujan
Data Tables
Why We Chose This Topic
Orange juice is a popular drink consumed all over the world for its nutritious value

But how healthy are the commercially produced juices?

We investigated three brands, one of them being organic
Flavour Packets
The juice is stripped of its natural flavour and colour.
This juice is deoxygenized to remove pathogens.
Flavour packets made from residue of oranges are added.
The flavour packets are not legally required to be stated in the label.
*Citric Acid Concentration = Volume of sodium hydroxide x 0.0064

Linking the Three Aspects
Which is the best brand?
Physics- Viscosity and concentrates

Chemistry- The effect of pH and citric acid

Biology- Glucose Content
Based on our qualitative data,
It is found that the juices have been found to have a lower glucose content.
However, they are all minute differences observed.
Brand 3 has the lowest glucose content.
Data Collected
Full transcript