Molarity and Percent Solution Lab Essay

Objective: The objective of this lab was to determine the molarity and percent solution of a solution with an unknown concentration. Background: Molarity is the number of moles of a solute per liter of a solution. Percent solution is the percentage of a solute in a specific mass or volume of a solvent. A solute is a solid that gets dissolved in a solvent or a liquid that is a smaller amount than the solvent. A solvent is a liquid that dissolves the solute and it always is a larger amount. Solvation is when solute particles are surrounded by solvent molecules. A lab technique that was used during the lab was to boil the solution in order to separate the solute from the solvent. Materials List: – 10mL graduated cylinder – Solution with unknown concentration – Hot plate – Pipette – Hot grip – Scale – 100mL beaker Procedure: 1. Obtain the solution with the unknown concentration from Mrs. Magdaleno. 2. Measure the volume of the solution by pouring it in the 10mL graduated cylinder. Use the pipette to take out solution in the graduated cylinder until the volume was at 6mL. Record it in the data table. 3. Measure the empty 100mL beaker using the scale. Record it in the data table. 4. Pour the solution in the 100mL beaker. 5. Find the mass of the beaker and solution using the scale. Make sure to subtract original beaker mass from the mass of the beaker and solution. 6. Boil the solution to separate the solute from the solvent by using the hot plate set to nine. 7. Once all the water has evaporated use the hot grips to remove the beaker from the hot plate and let cool. Find the mass of the beaker and solute using the scale. Make sure to subtract beaker mass from the beaker and solute mass. 8. Use the data from the data table to solve for molarity and percent solution. Observations: – The water started to boil and evaporate when it was on the hot plate. – It smelt like the salt was burning. – Some salt spilled out on the lab station when the water completely evaporated. Data Table: |Volume of solution (L) |6mL=0.006L | |Mass of beaker (g) |68.95g | |Mass of solution and beaker(g) |75.06g | |Mass of solution(g) |6.12g | |Mass of solute and beaker(g) |69.41g | |Mass of solute(g) |0.46g | Results: A: Molarity B: Percent Solution Conclusion: The molarity that was calculated for the unknown solution was 1.31M. The percent solution that was calculated for the unknown solution was 7.52%. A procedural that would have led to a lower concentration value was when some salt spilled out onto the lab station after all of the water had evaporated from the beaker. Another error that would result in a higher concentration would be if the beaker was not dry when the mass was measured with the scale. Something that could be done differently to lead to a more accurate concentration would be to take the beaker off the hot plate sooner and not let the salt sit and burn or come out of the beaker.