Concentration Citric Acid in Lemon Juice?

In summary, the author did an acid/base titration to investigate whether the concentration of citric acid lemon juice will change over a period of 5 days. The average titre values for this experiment, when 0.2 M of NaOH is in the burette, and 60 ml of diluted lemon juice is in the conical flask, was around 23.1-23.8. However, the author doubts that the concentration of citric acid will vary over a period of 5 days. He needs a idea of values for his 2nd question, which is what the average titre values for this experiment, when 0.2 M of NaOH is in the burette, and 60 ml of diluted lemon juice is
  • #1
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Hey there ppl!
I am doing an Acid/Base Titration to investigate whether the concentration of citric acid lemon juice, change over a period of 5 days. So i kindda need some help in this experiment, cause we are not allowed to ask our teacher any help! The main purpose of this experiment is that to see if we can do an experiment without any inputs from our teacher. So i had to come up with my own method and do my own experiment, and plus no one in our school can do the same experiment, so therefore we can't compare out results with anyone else.

So my questions are:

1. Will the concentration of citric acid actually varies over a period of 5 days?
My Answer : Nope, it won't vary, cause a period of 5 days is too less

2. What are the average titre values for this experiment, when 0.2 M of NaOH is in the burette, and 60 ml of diluted lemon juice is in the conical flask?
My answer: The values i got were around 23.1-23.8

These are my answers, can someone here check my answer if you guys have done this experiment?

I never got a Not Achevied in my entire chemistry assessment, so i don't want to fail this one, Only 3 ppl out of my whole country got an Excellence for this experiment, so i am really scared about passing with an Excellence. Can someone here help me please?
 
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  • #2
My comment: 3% error in titration is a lot.

1st answer seems logical to me. Citric acid is rather stable. The question is if the citric acid is the only acidic substance present in the juice and if these other substances (if they exist - I have no idea) - are stable too.

But I will start with the asumption that it is citric aicd only.
 
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  • #3
The devil is in the details. Think about the equilibriums, they can be expressed as concentration ratios or rate constant ratios. So how long does it take to obtain the equilibrium ?
 
  • #4
I don't get you. Could you elaborate?
 
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  • #5
1. Will the concentration of citric acid actually varies over a period of 5 days?
My Answer : Nope, it won't vary, cause a period of 5 days is too less

all in all, the most important thing is your experimental setup. Hint: you'll need a lot of lemons

you'll also need to be familiar with basic statistical analysis. However this may be a bit too much at your level.

In general you'll probably need to take lemons of the same size and roughly the same citric acid content (pH) and determine the citric acid content over the 5 days, each day working with a set of lemons.

You'll need to understand why citric acid exist in a lemon, the biology of it all and I'm not quite sure if this will be very interesting.
 
  • #6
Borek said:
I don't get you. Could you elaborate?


Borek

Sorry I misread your question. I was thinking of something totally different. my bad
 
  • #7
Hey there Guys!

Borek
Well yeah i am assuming that all the acid in lemon are citric acid, I know there maybe other acids persent in lemon, but i don't care about them, i am only ineterested about citric acid, and i will state it in my Evaluation & Limitation that i assumed that the only acid present in lemon juice in citric! This will give me something to write under the Evaluation part!

CGT
Yeah even my dad was saying something about taking the same size lemon and with the same amount of acid, but i did my experiment with Pure Lemon Cordial, i added 20 mL of the Lemon cordial and 80 mL of water and diluted the cordial. The bottle told me that for every 1 part of lemon i should add 4 parts of water, so the dilution factor was easy to calculate. The reason why i did this was, if i didn't add water, no one can drink the lemon cordial cause its too strong, and the burette readin will under 10mL, and we were instructed not to get any results under 10mL!

Now my first answer doubt is cleared. Many people that i know from other schools has also agreed that the concentration won't change too much, it will be quite constant. But i need a idea of values for my 2nd question. Does anyone know?

Thank You so much for replying and helping me out ppl!
 

1. What is citric acid and why is it important in lemon juice?

Citric acid is a weak organic acid that occurs naturally in citrus fruits, such as lemons. It is important in lemon juice because it gives the fruit its characteristic sour taste and acts as a natural preservative.

2. How is the concentration of citric acid determined in lemon juice?

The concentration of citric acid in lemon juice can be determined through titration, a chemical process that involves adding a known amount of base to a known amount of acid until a neutralization point is reached. The amount of base used can then be used to calculate the concentration of citric acid.

3. What is the typical concentration of citric acid in lemon juice?

The typical concentration of citric acid in lemon juice ranges from 4-8%, with an average of 5-6%. The exact concentration can vary depending on factors such as the ripeness of the lemons and the juicing method used.

4. How does the concentration of citric acid in lemon juice affect its taste and shelf life?

The concentration of citric acid in lemon juice directly affects its taste, with higher concentrations resulting in a more sour taste. It also acts as a natural preservative, so a higher concentration can increase the shelf life of lemon juice by inhibiting the growth of bacteria and other microorganisms.

5. Can the concentration of citric acid in lemon juice vary between different types of lemons?

Yes, the concentration of citric acid in lemon juice can vary between different types of lemons. For example, Meyer lemons tend to have a lower concentration of citric acid compared to other types of lemons. Additionally, the concentration can also vary depending on the growing conditions and ripeness of the lemons.

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