So a tonicity experiment was performed.
- One tube filled with 45% glucose was placed in D.I water, while another tube was filled with 15% NaCl and also placed in DI water.
When checked for a change in weight, the weight change for glucose was higher compared to the weight change of NaCl.
Can anybody explain to me why please?
The experiment you described involves testing the tonicity of two solutions: one containing 45% glucose and the other containing 15% NaCl. Tonicity refers to the ability of a solution to cause a change in the shape or size of cells through the process of osmosis.
In this case, the tubes filled with the glucose and NaCl solutions were placed in DI (deionized) water. To understand why the weight change for the glucose tube was higher compared to the NaCl tube, we need to consider the concepts of osmosis and tonicity.
Osmosis is the movement of solvent molecules (in this case, water) across a semipermeable membrane from an area of lower solute concentration to an area of higher solute concentration. A semipermeable membrane allows only certain molecules or ions to pass through while preventing others from crossing.
When a cell is placed in a solution, the direction of water movement (or osmosis) depends on the relative tonicity of the cell and the solution. Tonicity is determined by the concentration of solutes (such as glucose or NaCl) in the solution compared to the concentration of solutes inside the cell.
In the case of the 45% glucose solution, it has a higher concentration of solutes compared to the DI water. This means that the glucose solution is hypertonic to the water. Hypertonic solutions have a higher solute concentration and lower water concentration compared to the solution they are compared with. In this scenario, the glucose solution has a higher osmolarity than the DI water.
In contrast, the 15% NaCl solution has a lower concentration of solutes compared to the DI water. This makes the NaCl solution hypotonic to the water. Hypotonic solutions have a lower solute concentration and higher water concentration compared to the solution they are compared with. Therefore, the NaCl solution has a lower osmolarity than the DI water.
Now, let's consider what happens when the tubes are placed in DI water. Since the glucose solution is hypertonic to the water, water molecules will move from the area of higher water concentration (DI water) to the area of lower water concentration (glucose solution) through osmosis. As a result, the water will enter the tube with the glucose solution, leading to an increase in weight.
On the other hand, the NaCl solution is hypotonic to the water. This means that the water molecules will move from the area of higher water concentration (NaCl solution) to the area of lower water concentration (DI water) through osmosis. As a result, water will exit the tube with the NaCl solution, causing it to lose weight.
In summary, the weight change for the glucose solution was higher compared to the NaCl solution because the glucose solution is hypertonic and the NaCl solution is hypotonic to the DI water. This means that water moved into the tube with the glucose solution, increasing its weight, while water moved out of the tube with the NaCl solution, causing it to lose weight.