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Janet Tran

Mrs. Canady

Chemistry Honors

November 25, 2013

Sugar Percentage in Beverages Lab Report

The objective of the experiment was to determine the percentage of sugar in various

beverages using a handmade hydrometer. The handmade hydrometer could be calibrated to

measure a known percentage of sugar in water and then used to determine the percentage of

sugar in each beverage in comparison. After completing the experiment, the percentages

collected were compared to the actual percentages of sugar in each drink to check the accuracy

of the measurements.

The hydrometer measures the relative density of liquids, a ratio of the density of a liquid

to the density of water. Generally, hydrometers are glass tubes with a bulb at one end weighted

with mercury or lead shots to enable it to float straight. After the liquid being tested is poured

into a graduated cylinder, the hydrometer is dropped into the liquid until it floats. Where the

liquid’s surface touches the stem of the hydrometer, which usually contains a scale, tells the

experimenter the relative density of the liquid. In liquids with low densities, the hydrometer will

sink lower, while in high-density liquids it will float higher. The Greek Scholar Hypatia is

credited for the invention of the first hydrometer, also known as the hydroscope, back in the 4th

or 5th century. Since then, other key scientific figures in history have mentioned the hydrometer

in their works, such as Galileo and others have improved and developed new models of the

hydrometer such as William Nicholson and Antoine Baumé. Especially during 18th and 19th

century in Europe, the hydrometer came into demand to settle conflict over alcohol taxation.

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More recently other uses and models of the hydrometer have been developed. These include the

lactometer, which measures the density of milk; the alcohol meter, which determines the

alcoholic strength of beverages; the saccharometer, which determines the density of sugar in a

solution; the thermohydrometer, which measures the density of petroleum products; the

urinometer, which measures the ratio of solute, or wastes, to water to evaluate a patient’s level

of hydration; and the battery hydrometer, which determines the charge of a lead-acid battery

using the density of the sulfuric acid solution.

In this particular experiment, a hydrometer was fashioned out of a dropper and an iron

nail punctured into the bulb of the dropper. A hundred millimeter graduated cylinder was filled

with water and the hydrometer placed into the water to calibrate it. Before placing the

hydrometer in the water, the bulb of the dropper was filled at least a third of the way with water.

The height of the stem from the surface of the water was noted to be compared to other solutions

later on. The calibrated height was 6.2 cm high. Four, eight, twelve and sixteen percent sugar-

water solutions were then created. On a triple beam balance, four, eight, twelve, and sixteen

grams of sugar were weighed, not including the weight of the container used to hold the sugar.

Each amount of sugar was mixed with ninety-six, ninety-two, eighty-eight, and eighty-four

grams of water respectively to create the solutions with the correct percentages of sugar. These

solutions were then each poured into a smaller, fifty millimeter graduated cylinder for the

hydrometer to be dropped into. When dropped into the four percent solution, the height of the

stem measured 6.7 cm. When dropped into the eight percent solution, it measured 8.0 cm. In the

twelve percent solution, it measured 10.1 cm and in the sixteen percent solution, it measured

11.2 cm. These results were then plotted on a graph to create a standard curve, with the height of

the stem in centimeters on the y-axis and the percentage of sugar on the x-axis. Red Gatorade,

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Yellow Gatorade, Orange Gatorade, Pepsi, Grape Crush, and Orange Crush were then each

poured into the fifty millimeter graduated cylinder. The hydrometer was dropped into each and

the height of the stem recorded. All the Yellow, Red, and Orange Gatorade had a height of 7.0

cm. The Pepsi had a height of around 8.2 cm. The Orange Crush had a height of 7.7 cm, and the

Grape Crush had a height of 8.1 cm. The percentage of sugar in each beverage could be

estimated from these heights using the standard curve from the earlier measurements, where the

percentage of sugar was known.

All the Gatorade flavors were calculated to have 2.5 percent sugar, but the actual

percentage of sugar for each flavor of Gatorade is around 6.0 percent. This creates a large

percent error of 58.3 percent. In the experiment, the sugar percentage of Pepsi was estimated to

be around 5.7 percent, but the actual percentage is 12.1 percent sugar. The percent error here is

53.0 percent. The Orange Crush soda was found to have 4.4 percent sugar and the Grape Crush

Soda was found to have 5.6 percent sugar. Unfortunately, the actual sugar percentages for both

flavors of Crush Soda have 12.5 percent sugar. Consequently, the percent error was 64.8 percent

for Orange Crush Soda and 55.2 percent for Grape Crush Soda. Obviously, the results generated

from the experiment were not very accurate or remotely close the actual percentage of sugar

Beverage Experimental Sugar %

Actual Sugar % Percent Error

Red Gatorade 2.5% 6.0% 58.3%

Orange Gatorade 2.5% 6.0% 58.3%

Yellow Gatorade 2.5% 6.0% 58.3%

Orange Crush 4.4% 12.5 % 64.8 %

Grape Crush 5.6% 12.5% 55.2%

Pepsi 5.7% 12.1% 53.0 %

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This particular technique should have worked in theory for this experiment, but presented

too many inconsistencies to be appropriate for the experiment. A major issue with this technique

was the amount of water that was in the bulb of the dropper when measuring the percentages. If

the amount of water in the bulb in each trial was not the same, then the results meant nothing

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since the calibration would be different. To improve results, there should be a more constant

weight on the hydrometer, as it is with more professional hydrometers. Human error also had a

hand in these inconsistencies. A normal ruler was used to measure the height of the stem, and

often enough students estimate by a wide margin. In this case, the students had to hold the ruler

next to the stem, measuring from the surface of the water to the top of the stem. Often, when the

hydrometer was dropped into the solutions, the liquid would overflow from the cylinder, causing

the level of water to lower. This made it more difficult to place the ruler exactly at the point that

it needed to be to accurately measure the height. It would have been more beneficial to have

markings on the actual stem, as normal hydrometers would have. Misreading the height by a

couple of millimeters can change a result drastically. Overall, the tool used to measure the

percentages played a key role in the results of the experiment along with the human errors

involved. The large percent errors can be chalked up to these types of inconsistencies and lack of

better measuring methods. Perhaps if a better method was used to measure the readings of the

hydrometers without any inconsistencies, the results would have been more accurate. Obviously,

in the factories of the companies that produce these beverages, there are more advanced ways of

calculating these types of measurements. The amounts of sugar in commercial beverages were

probably calculated by computers and machines or people with professional tools, not high

school students who can and often make mistakes.

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Works Cited

"Crush Soda Official Site." Crush Soda Official Site. Dr, Pepper Snapple Group, 2013. Web. 24

Nov. 2013. <http://www.crushsoda.com/>.

"Gatorade Lemon Lime." Nutrition Info For Pepsi. Pepsico, 29 Oct. 2013. Web. 24 Nov. 2013.

<http://www.pepsicobeveragefacts.com/infobyproduct.php?prod_type=1026>.

"Gatorade Orange.” Nutrition Info For Pepsi. Pepsico, 29 Oct. 2013. Web. 24 Nov. 2013.

<http://www.pepsicobeveragefacts.com/infobyproduct.php?prod_type=1026>.

"Gatorade Strawberry." Nutrition Info For Pepsi. Pepsico, 29 Oct. 2013. Web. 24 Nov. 2013.

<http://www.pepsicobeveragefacts.com/infobyproduct.php?prod_type=1026>.

"Hydrometer." Wikipedia. Wikimedia Foundation, 11 June 2013. Web. 23 Nov. 2013.

<http://en.wikipedia.org/wiki/Hydrometer>.

Mitchell, Josalin. "The History of the Hydrometer | EHow." EHow. Demand Media, 21 Sept.

2009. Web. 24 Nov. 2013. <http://www.ehow.com/about_5438638_history-

hydrometer.html>.

"Pepsi." Nutrition Info For Pepsi. Pepsico, 29 Oct. 2013. Web. 21 Nov. 2013.

<http://www.pepsicobeveragefacts.com/infobyproduct.php>.