Beverage Density Lab Report .docx



Carly Kosinski

Period 4

10/23/13

Beverage Density Lab Report

Background

The density of a pure substance is a characteristic physical property that can be

used to identify the substance. Density is defined as the ratio of mass per unit

volume. It is an “intensive” property, that is, it does not depend on the amount of

the substance. The density of any material is determined by measuring its mass

and volume and then dividing the mass of the volume. The mass of a substance

can be measured directly using a balance. The volume of a liquid can also be

measured directly using special laboratory glassware, such as a graduated

cylinder, a buret, or a pipet. In this experiment, liquid volumes will be measured

using a graduated cylinder.

The density of a solution depends on its concentration, that is, how much solute

(solid) is dissolved in the solvent (liquid). The higher the concentration of solute,

the greater the density of the solution. A convenient way to express concentration

is in units of weight percent, which corresponds to the number of grams of solute

that are present in 100 g of solution. A 20% salt solution is prepared by dissolving

20 g of sodium chloride in 80 g of water. (Notice that the final mass of the

solution is 100 grams.) If the density of a solution is plotted on a graph against the

concentration of solute, a regular patten is evident. Density is directly

proportional to concentration. A 20% salt solution, for example, has a greater

density than a 10% salt solution. If the densities of several solutions of known

concentration are determined experimentally, a calibration curve (graph) can be

constructed that shows a straight-line relationship between the density of a

solution and the concentration of the calibration curve can then be used to

find the concentration of solute in an unknown solution. I wonder what factors determine the the density of a solution? Can the density of a solution be used to determine how much of a particular substance is dissolved in it?

Hypothesis

If the sugar content relationship to density is correct, then the Percentages will equal the information provided on nutrition labels.

Procedure

Materials:

balance small beaker, 5 sugar solutions graduated cylinder, 4 beverages plus unknown

Safety: goggles, glass breakage, spills

1. Calculate and plot Part A’s densities on a graph and for a calibration curve of density versus percent sugar concentration.

2. Calculate the density of the four beverages and an unknown.

3. Plot density versus concentration for the five reference solutions on a graph. Use a ruler to draw the “best-fit” straight line through the data points. Use the graph to estimate the unknown sugar concentrations in the first beverage. The point where this vertical “line” meets the x-axis equals the percent concentration of sugar in the beverage solution.

4. Use a calibration curve to find how much sugar they contain.

5. Record the density of the beverages and the estimated percent sugar concentration in a Results Table.

6. Compare the results to the percentages on the nutrition label of the beverages.

7. Calculate the percent error of the experimental percent sugar and the percent sugar concentrate given on the nutrition label.

8. Record your percent error in the Results table.

Data Table A: Density of Reference Solutions

|Solution |Mass, g |Sample Volume, mL |Density, g/mL |

|0% Sugar |9.45 g |10.00 |.945 g/ml |

|5% Sugar |9.51 g |10.00 |.951 g/ml |

|10% Sugar |9.56 g |10.00 |.956 g/ml |

|15% Sugar |9.89 g |10.00 |.989 g/ml |

|20% Sugar |10.11 g |10.00 |1.011 g/ml |

Data Table B: Beverage Densities

|Beverage |Mass, g |Sample Volume, mL |Density, g/mL |

|Powerade |9.95 g |10.00 |0.995 g/ml |

|Diet Pepsi |9.75 g |10.00 |0.975 g/ml |

|Pepsi |12.40 g |10.00 |1.24 g/ml |

|Lemonade |10.18 |10.00 |1.018 g/ml |

|Apple Juice |10.20 |10.00 |1.02 g/ml |

|Unknown _____ |10.15 g |10.00 |1.015 g/ml |

Results Table:

|Beverage |Experimental % sugar |

|Powerade |5% |

|Diet Pepsi |0% |

|Apple Juice |11% |

|Pepsi |9% |

|Lemonade |13% |

Post-Lab: Results Table

|Beverage |Measured density, g/mL|Percent sugar |Amount of sugar |Percent sugar |Percent error |

| | |(experimental) |(Nutrition label) |(calculated from | |

| | | | |Nutrition label) | |

|Pepsi |1.24 g/ml |9% |41g/355mL |11% |-18% |

|Diet Pepsi |.975 g/ml |0% |0g/355mL |0% |0% |

|Apple Juice |1.02 g/ml |11% |27g/240mL |11% |0% |

|Lemonade |1.018 g/ml |13% |31g/ 240mL |12% |8% |

Analysis

My measured density for pure water was .945 g/ml. My measurement might be higher or lower due to the mass I calculated or the amount of volume could have been incorrectly measured out. If a beverage is diet, the sugar content will be decreased, or have zero. Different ingredients in the beverage can affect the mass and volume which would differ the density of the solution. When plotting data it is not appropriate to connect dots, because you would not be able to identify the relationship between the densities, estimated percent sugar concentration, and the percent sugar concentration given on the nutritional label. If I were to do the lab again, I don’t think I would get the same results, because I did not angle my calibration curve exactly how it should have been angled. This error affected my results when I drew a line to find the estimated percentage sugar concentration. For further study, I would make my estimates more precise, which would end with a better outcome for the lab.

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