Question 4
Experiment 4 — Alternative way to measure the density of liquid (35 points)
In this experiment you will measure density of water containing dissolved sugar at various concentrations without using laboratory instruments.
Apparatus: (1) A drinking glass; (2) a small plastic bottle; (3) a ruler; (4) a spoon; (5) three sachets of sugar; (6) drinking water; (7) graph paper.
Procedures
A) Measuring the mass of a filled plastic bottle
**1.** Measure the inner diameter of the glass. Note it as $D$ (in cm). $D=\ldots$
**2.** Fill the plastic bottle with a small amount of drinking water (approximately $1/5$ of its volume), and then close tightly.
**3.** Pour drinking water in the glass until the water level reaches around half of the glass.
**4.** Measure the height of the water level in the glass using a ruler. Note it as $H_1$ (in cm). $H_1=\ldots$
**5.** Place gently the plastic bottle into the glass containing water and measure the height of the water level in the glass. Note it as $H_2$ (in cm). $H_2=\ldots$
**6.** Calculate the volume of water displaced by the plastic bottle. Answer: …
**7.** Calculate the mass of water displaced by the plastic bottle using the density of pure water of 1 g/cm³. The mass of the filled plastic bottle is equal to the mass of the displaced water. Answer: …
B) Measuring the density of water containing dissolved sugar at various concentrations
**8.** Take out the plastic bottle from the glass.
**9.** Pour one sachet of sugar into the glass containing water and stir until the sugar dissolves completely.
**10.** Repeat steps 4 to 6.
**11.** The mass of displaced liquid is equal to the mass of the filled plastic bottle. Then calculate the density of liquid ($P_1$) using the following formula:
$$P_1=\frac{\text{mass of the bottle}}{\text{volume of displaced liquid}}=\ldots$$
**12.** Increase the concentration of the sugar solution by adding the second sachet of sugar and repeat steps 8 to 11.
**13.** Continue to increase the concentration of the sugar solution by adding the last sachet of sugar and repeat steps 8 to 11.
**14.** Fill the following table:
| Sachets of sugar | Density of liquid (g/cm³) |
| --- | --- |
| 0 | … |
| 1 | … |
| 2 | … |
| 3 | … |
**15.** Plot a graph based on your data using the graph paper provided. The horizontal axis is the number of sachets and the vertical axis is the density of liquid.
Answer the following questions: Predict the density of liquid if you pour 1.5 sachets of sugar. What is the density if you pour 3.5 sachets of sugar into the same volume of water as used in the experiment above? Assume that the sugar can be dissolved completely.
In this experiment you will measure density of water containing dissolved sugar at various concentrations without using laboratory instruments.
Apparatus: (1) A drinking glass; (2) a small plastic bottle; (3) a ruler; (4) a spoon; (5) three sachets of sugar; (6) drinking water; (7) graph paper.
Procedures
A) Measuring the mass of a filled plastic bottle
**1.** Measure the inner diameter of the glass. Note it as $D$ (in cm). $D=\ldots$
**2.** Fill the plastic bottle with a small amount of drinking water (approximately $1/5$ of its volume), and then close tightly.
**3.** Pour drinking water in the glass until the water level reaches around half of the glass.
**4.** Measure the height of the water level in the glass using a ruler. Note it as $H_1$ (in cm). $H_1=\ldots$
**5.** Place gently the plastic bottle into the glass containing water and measure the height of the water level in the glass. Note it as $H_2$ (in cm). $H_2=\ldots$
**6.** Calculate the volume of water displaced by the plastic bottle. Answer: …
**7.** Calculate the mass of water displaced by the plastic bottle using the density of pure water of 1 g/cm³. The mass of the filled plastic bottle is equal to the mass of the displaced water. Answer: …
B) Measuring the density of water containing dissolved sugar at various concentrations
**8.** Take out the plastic bottle from the glass.
**9.** Pour one sachet of sugar into the glass containing water and stir until the sugar dissolves completely.
**10.** Repeat steps 4 to 6.
**11.** The mass of displaced liquid is equal to the mass of the filled plastic bottle. Then calculate the density of liquid ($P_1$) using the following formula:
$$P_1=\frac{\text{mass of the bottle}}{\text{volume of displaced liquid}}=\ldots$$
**12.** Increase the concentration of the sugar solution by adding the second sachet of sugar and repeat steps 8 to 11.
**13.** Continue to increase the concentration of the sugar solution by adding the last sachet of sugar and repeat steps 8 to 11.
**14.** Fill the following table:
| Sachets of sugar | Density of liquid (g/cm³) |
| --- | --- |
| 0 | … |
| 1 | … |
| 2 | … |
| 3 | … |
**15.** Plot a graph based on your data using the graph paper provided. The horizontal axis is the number of sachets and the vertical axis is the density of liquid.
Answer the following questions: Predict the density of liquid if you pour 1.5 sachets of sugar. What is the density if you pour 3.5 sachets of sugar into the same volume of water as used in the experiment above? Assume that the sugar can be dissolved completely.