Michelle Hupje
An investigation into the relationship between price and citric acid content in lemonades
as determined by a neutralization reaction and titration with NaOH.
Introduction
Research Question
What is the relationship between price of lemonade – specifically Coles, Schweppes and Sprite –
and citric acid content as measured by neutralization with NaOH? This investigation will further
examine if there is a correlation between price and citric acid content of lemonades.
Background information
Numerous studies have shown the debilitating effects of citric acid on enamel. Hughes, West,
Parker, Braak and Addy (2000) examined the effects of soft drink corrosion on enamel –
particularly investigating the effect of citric acid and determine the effectiveness of adding
calcium to soft drinks to reduce the erosivity of soft drinks (Hughes, West, Parker, Braak and
Addy, 2000). The study concluded that pH, citric acid concentration and calcium concentration
all intertwine and ultimately, the manipulation of calcium concentrations in soft drinks can
counter act the erosivity of citric acid (Hughes, West, Parker, Braak and Addy, 2000).
Thus, research has been conducted into replacements for citric acid such as the traditional
sucrose or a novel ‘aspartame’ (Bonnans and Noble, 1993). However, when using only sucrose or
aspartame studies have continuously shown that there is a greater suppression of the traditional
sourness associated with lemonade (Veldhuizen, Siddique, Rosenthal and Marks, 2017). Thus,
citric acid is continued to be used in many soft drinks as no suitable replacement has been
produced at an economically advantageous price (Show, Oladele, Siew, Aziz Zakry, Lan, and Ling,
2015).
Due to its many applications in numerous different industries, citric acid has a “high economic
demand” (Show, Oladele, Siew, Aziz Zakry, Lan, and Ling, 2015). It is generally produced through
the microbial fermentation of Aspergillus niger however, this method of production is time-
consuming and thus relatively expensive (Show, Oladele, Siew, Aziz Zakry, Lan, and Ling, 2015).
Thus, the hypothesis of this investigation is that as citric acid content in lemonades increases as
will the price since the artificial production of citric acid is relatively expensive.
Each of the brands this investigation will examine – Coles, Schweppes and Sprite arranged in
ascending order of price – is in a different price range, thus the hypothesis reflects that the more
expensive brands will have a higher citric acid content. However, research into citric acid
content in lemonades has shown that the values will range between 0.03 to 0.22g/50mL –
hereby, the hypothesis expects this investigation’s results to reflect this literature (Penniston,
Nakada, Holmes and Assimos, 2008).
Hypothesis
Null hypothesis (H0): There will be no statistically significant correlation between price and
citric acid content of lemonades.
Experimental hypothesis (H1): There will be a statistically significant, positive correlation
between the citric acid content and price of lemonades.
1
, Michelle Hupje
Variables
The operationalised independent variable for this experiment is the price of each lemonade
analysed – in this case Schweppes, Coles and Sprite. The dependent variable is the citric acid
content per each can of lemonade (g/350mL). The controlled variables and methods of
controlling them are outlined below.
Variable Method of controlling
Concentration of NaOH The concentration of NaOH to be used
was determined prior to the
experiment – 0.1M – and a pre-
prepared standardized NaOH (0.1M)
solution was used for all conditions to
ensure the concentration remained
constant.
Volume of lemonade sample used 50mL ( ±1.0 mL ) of each sample
lemonade was used, measured by the
measuring cylinder.
Amount of phenolphthalein A set value of 3 drops of
indicator used phenolphthalein indicator was used in
each trial for every independent
variable (lemonade brand).
Amount of carbonic acid in All lemonade samples were shaken and
lemonade samples opened 48 hours prior to titration to
ensure carbonic acid was removed.
Before titration commenced, samples
were shaken once more to ensure that
there was no trace of carbonic acid
(evidenced by a lack of bubbles).
Method
Materials/apparatus
600mL of NaOH (0.1 M)
300mL of Sprite lemonade
300mL of Schweppes lemonade
300mL of Coles lemonade
1x Burette ( ± 0.075 mL )
1x Phenolphthalein indicator
1x White tile
2x 250mL Erlenmeyer flasks
1x Deionized water
1x 100mL measuring cylinder ( ±1.0 mL )
1x Pipette bulb
1x Pipette ( ± 0.04 mL )
1x Glass funnel
Procedure
1. Prior to titration the cans of Sprite and Schweppes were shaken and opened to ensure all
carbon dioxide and carbonic acid was removed.
2
An investigation into the relationship between price and citric acid content in lemonades
as determined by a neutralization reaction and titration with NaOH.
Introduction
Research Question
What is the relationship between price of lemonade – specifically Coles, Schweppes and Sprite –
and citric acid content as measured by neutralization with NaOH? This investigation will further
examine if there is a correlation between price and citric acid content of lemonades.
Background information
Numerous studies have shown the debilitating effects of citric acid on enamel. Hughes, West,
Parker, Braak and Addy (2000) examined the effects of soft drink corrosion on enamel –
particularly investigating the effect of citric acid and determine the effectiveness of adding
calcium to soft drinks to reduce the erosivity of soft drinks (Hughes, West, Parker, Braak and
Addy, 2000). The study concluded that pH, citric acid concentration and calcium concentration
all intertwine and ultimately, the manipulation of calcium concentrations in soft drinks can
counter act the erosivity of citric acid (Hughes, West, Parker, Braak and Addy, 2000).
Thus, research has been conducted into replacements for citric acid such as the traditional
sucrose or a novel ‘aspartame’ (Bonnans and Noble, 1993). However, when using only sucrose or
aspartame studies have continuously shown that there is a greater suppression of the traditional
sourness associated with lemonade (Veldhuizen, Siddique, Rosenthal and Marks, 2017). Thus,
citric acid is continued to be used in many soft drinks as no suitable replacement has been
produced at an economically advantageous price (Show, Oladele, Siew, Aziz Zakry, Lan, and Ling,
2015).
Due to its many applications in numerous different industries, citric acid has a “high economic
demand” (Show, Oladele, Siew, Aziz Zakry, Lan, and Ling, 2015). It is generally produced through
the microbial fermentation of Aspergillus niger however, this method of production is time-
consuming and thus relatively expensive (Show, Oladele, Siew, Aziz Zakry, Lan, and Ling, 2015).
Thus, the hypothesis of this investigation is that as citric acid content in lemonades increases as
will the price since the artificial production of citric acid is relatively expensive.
Each of the brands this investigation will examine – Coles, Schweppes and Sprite arranged in
ascending order of price – is in a different price range, thus the hypothesis reflects that the more
expensive brands will have a higher citric acid content. However, research into citric acid
content in lemonades has shown that the values will range between 0.03 to 0.22g/50mL –
hereby, the hypothesis expects this investigation’s results to reflect this literature (Penniston,
Nakada, Holmes and Assimos, 2008).
Hypothesis
Null hypothesis (H0): There will be no statistically significant correlation between price and
citric acid content of lemonades.
Experimental hypothesis (H1): There will be a statistically significant, positive correlation
between the citric acid content and price of lemonades.
1
, Michelle Hupje
Variables
The operationalised independent variable for this experiment is the price of each lemonade
analysed – in this case Schweppes, Coles and Sprite. The dependent variable is the citric acid
content per each can of lemonade (g/350mL). The controlled variables and methods of
controlling them are outlined below.
Variable Method of controlling
Concentration of NaOH The concentration of NaOH to be used
was determined prior to the
experiment – 0.1M – and a pre-
prepared standardized NaOH (0.1M)
solution was used for all conditions to
ensure the concentration remained
constant.
Volume of lemonade sample used 50mL ( ±1.0 mL ) of each sample
lemonade was used, measured by the
measuring cylinder.
Amount of phenolphthalein A set value of 3 drops of
indicator used phenolphthalein indicator was used in
each trial for every independent
variable (lemonade brand).
Amount of carbonic acid in All lemonade samples were shaken and
lemonade samples opened 48 hours prior to titration to
ensure carbonic acid was removed.
Before titration commenced, samples
were shaken once more to ensure that
there was no trace of carbonic acid
(evidenced by a lack of bubbles).
Method
Materials/apparatus
600mL of NaOH (0.1 M)
300mL of Sprite lemonade
300mL of Schweppes lemonade
300mL of Coles lemonade
1x Burette ( ± 0.075 mL )
1x Phenolphthalein indicator
1x White tile
2x 250mL Erlenmeyer flasks
1x Deionized water
1x 100mL measuring cylinder ( ±1.0 mL )
1x Pipette bulb
1x Pipette ( ± 0.04 mL )
1x Glass funnel
Procedure
1. Prior to titration the cans of Sprite and Schweppes were shaken and opened to ensure all
carbon dioxide and carbonic acid was removed.
2
