The final weight of the 10 mL 5 M NaCl solution prepared by Student A at 20°C will not be the same as the one prepared by Student B at 80°C. Here’s why:

Explanation

1. Density Variation with Temperature: The density of water (and hence the NaCl solution) changes with temperature. At 20°C, water is denser than at 80°C. Since density decreases as temperature increases, the same volume of a solution (10 mL in this case) will weigh less at a higher temperature (80°C) than at a lower temperature (20°C).

2. Solution Preparation: In both cases, they are making a 5 M NaCl solution, meaning both are dissolving the same moles of NaCl in the same final volume of 10 mL of water. However, because the density of water changes with temperature, the mass of the final 10 mL solution will differ. At 80°C, the solution is less dense, so the mass of the 10 mL solution will be less than that at 20°C.

Summary

• 20°C (Student A): Higher density leads to a heavier 10 mL solution.
• 80°C (Student B): Lower density leads to a lighter 10 mL solution.

Therefore, the solution prepared by Student A at 20°C will have a greater final weight than the one prepared by Student B at 80°C.

Calculation Algorithm to Convert Molarity to Mass of Solution

To calculate the mass of a solution given its molarity (M), volume (V), and temperature (affecting density), you can use the following algorithm:

1. Define Variables:

   • M = Molarity of the solution (mol/L)
   • V = Volume of the solution (L)
   • MW = Molar mass of solute (NaCl = 58.44 g/mol)
   • ρ(T) = Density of the solution at temperature T (g/mL) (this value depends on T)
   • V_mL = Volume in mL = $V \times 1000$
   • mass_solution = Total mass of the solution

2. Calculate Mass of NaCl: $\text{mass\_NaCl} = M \times V \times MW$

3. Estimate the Density of the Solution:
   The density ρ(T) can be found in standard tables for different temperatures and concentrations or approximated based on the density of water adjusted for the presence of NaCl.

4. Calculate the Mass of the Solution Using Density and Volume: $\text{mass\_solution} = \rho(T) \times V_{mL}$

5. Return mass_solution

Example Steps for the Given Problem:

1. Determine the density of the NaCl solution at 20°C and 80°C (from tables).
2. Calculate the mass of the solution for both temperatures.

Would you like a step-by-step numerical example to illustrate this?

Follow-Up Questions

1. How does the density of water vary with different temperatures?
2. What role does molarity play in determining the concentration of a solution?
3. Why is the density of NaCl solutions not exactly the same as pure water?
4. How do you find the density of a solution if it is not directly provided in a problem?
5. How does temperature affect the solubility of salts like NaCl?

Tip

When preparing solutions where the final weight is important, always consider the temperature, as it can significantly affect the solution's density and thus its weight.