space.template.3.Lab1.Solubility+and+the+Dissolving+Process

=__Solubility and the Dissolving Process__=

**Background Information**
We have previously examined solubility in terms of saturated and unsaturated solutions. We also have an understanding of how temperature plays a key role in the amount of solute that may be dissolved. What exactly does it mean to dissolve a solute? In this activity you are going to examine what happens when you take a salt and dissolve in into water. In this scenario, the salt would be the solute because it is the substance that is dissolving and water would be the solvent, because it is the dissolving agent.

For the second half of this activity you will be ask to determine a solution concentration. The solution concentration refers to how much solute is dissolved into a specific quantity of solvent. For example a solution that contains 5 grams of NaCl (table salt) and 95 grams of water has a mass of 100 grams combined. The amount of salt is only 5% of the solutions mass, therefore we refer to the solution as being a 5% salt solution. We can also think about this salt solution as being a 5 parts per hundred (pph) salt solution. The solution having a mass of 100 grams or 100 parts and the salt only taking up 5% or 5 parts of the entire 100.

You may have also seen the abbreviations ppm or ppb. These stand for parts per million and parts per billion, respectively. A 5 ppm salt solution would contain 5 grams for every 999,995 grams of water or 0.000005 grams of salt per every 100 grams of water, etc.

**Pre-Lab Questions**
1) What is a solute?

2) What is a solvent?

3) What is a solution concentration?

4) What does pph stand for?

5) Hypothesis: Using the solubility curve here, predict if 30 grams of salt will saturate 70 grams of water. Remember, solubility curve is based on 100g of water, you are dissolving only into 70g. (Hint: Multiply saturation point by .70)

Procedure
__//Visualizing the Dissolving Process//__ For the first part of this activity, visit the following website: @http://phet.colorado.edu/en/simulation/soluble-salts You do not need to download the application, you only need to click Run Now, which will allow you to download a smaller file to run the application. 1.) Starting with the default settings (water and table salt), shake the salt shaker once or twice and record what happens to the NaCl ions as they come into contact with the water. Record these observations in the data section. 2.) Determine the maximum amount of salt that you can dissolve before the ions stop dissassociating when they hit the water. Record this number in the data section. 3.) Pick two other salts and repeat step two with them. Record this in the data section

__//Determining Solution Concentrations//__ 4.) When you are done with the simulation, grab materials from your teacher. You will need the following materials:
 * One empty clean paper cup
 * One paper cup with salt
 * Beaker
 * Spoon
 * Graduated cylinder

5.) Measure out 95 ml of water into the beaker. 95 ml of water is equal to 95 grams of water (Density of water = 1g/ml) 6.) Weigh the empty paper cup and then place about 5 grams of salt into the paper cup. 7.) Place salt in the beaker 8.) Record observations in Data Section. Does all of the salt dissolve. 9.) Rinse out beaker. Fill Beaker with 70 grams of water (70 ml). Measure out 30 grams of salt and stir into beaker. Record observations 10.) Clean and return all materials.

__//Visualizing Solubility//__
 * Data**
 * Describe what happened to the salt molecule as it hit the water:


 * What is the maximum amount of salt that you can dissolve, before the ions stop disassociating. Make sure you record the amount of water that you were dissolving the salt into. What is this called when the solution will not dissolve any more solute?


 * What is the maximum amount of solute that you were able to dissolve. Make sure you also record the amount of water that you were dissolving the salt into.

__//Determining Solution Concentration//__
 * Observation of 5 gram salt solution


 * Observation of 30g salt solution

Analysis
1) What happens to the ions when the solute dissolves into the solvent?

2) What happens to the ions when a solution becomes saturated?

3) What factors might play a role in the saturation level of the solvent?

4) How many parts per hundred was the 30gram salt solution?

5.) How many parts per million was the 5 gram salt solution?

Conclusion
How did the simulation help you to better understand the dissolving process? Restate your hypothesize from Pre-lab question #5. Were you correct? Explain any sort of errors that could have occurred while completing this activity.