Final answer:
When a dialysis tube containing a 25% sugar solution is placed in a beaker with a 12% sugar solution, water molecules will move into the dialysis tube due to osmosis, leading to an increase in the mass of the tube.
Step-by-step explanation:
The question involves understanding the principles of osmosis and diffusion through a semi-permeable membrane. If a dialysis tube containing a 25% sugar solution is placed in a beaker with a 12% sugar solution, over time, due to osmosis, water molecules will move from the area of lower solute concentration (the 12% sugar solution outside the tube) to the area of higher solute concentration (the 25% sugar solution inside the tube). This net movement of water will result in an increase in the mass of the dialysis tube.
Without experimental data, predicting the exact change in mass is challenging. However, the principles of diffusion and osmosis can lead us to expect that the mass will increase significantly due to the water entering the tube in an attempt to equalize the solute concentrations on both sides of the membrane. The 25% sugar solution has a much higher solute concentration than the 12% solution, so water will enter the dialysis tube until the concentrations are more similar, though equilibrium may not be reached in just 30 minutes.