Concentration And Molarity Phet Lab Answer Key

Concentration and Molarity PhET Labs Name: ________________________ Procedure: https://phet.colorado.edu/sims/html/concentration/latest/concentration_en.html Part 1: Dissolution and Saturation Take some time to play and familiarize yourself with the simulation. Click on everything. Move all the sliders. Notice what happens to the concentration as solid solute is added and when evaporation occurs. 1. How does the concentration change as solid solute is added? ____________________________________ 2. How does the concentration change as additional water is added? ________________________________ 3. How does the concentration change as evaporation occurs? ___________________________________________________ 4. How do you know when a solution is saturated? ____________________________________________________________ 6. When a solution is saturated, and additional solid solute is added, what happens? _________________________________ 7. Why do you think this is? _______________________________________________________________________________ 8. How does adding this additional solute change the concentration of this saturated solution? _________________________ 9. How does evaporation change the concentration of a saturated solution? ________________________________________ Part 2: Concentrated Solutions (same website as part 1 just click on the Solution option) 10. Adding a concentrated solution… describe a way to determine the concentration of the solution in the spigot. Write your plan here: _____________________________________________________________________________ _______________________________________________________________________________________________ 11. Using your plan…how might you get that concentrated solution to become saturated? ____________ _____________________________________________________________________________________ 12. Does your plan work for all the other solutions too? __________ Why? / Why Not?_____________________ ______________________________________________________________________________________________ Part 3: Molarity https://phet.colorado.edu/sims/html/molarity/latest/molarity_en.html Molarity is moles per Liter, that is, how many moles of solute (entire salt) is dissolved per Liter of solution. First, determine the saturation concentration of each of the solutions, that is, how concentrated can you get each solution before the solution is saturated. If you can’t determine the concentration using the simulation “Molarity”, try using the simulation “Concentration” (You will use this information again in Part 5, if your instructor requires it) Saturation concentration Saturation concentration )( )()( Lsolutionofvolume molsoluteofamountMMolarity = concentration increases concentration decreases concentration increased concentration does not change (it also shows on screen) solid does not dissolve and settles at bottom solvent cannot hold any more solute decreases concentration no change- solution is already saturated empty the container and add only one solution from the dropper and then use the sensor to measure concentration you can evaporate yes evaporation reduces the amount of water (or solute) so concentration increases 5.640 M 4.330 M 2.30 M 0.510 M 3.350 M 5.210 M 1.380 M 0.480 M Concentration and Molarity PhET Labs Name: ________________________ Part 4: Calculating Molarity Using the simulation and the formula for Molarity on the front, complete the table below. Moles of Compound (mol) Liters of Solution (L) Molarity of Solution (M) Moles of Compound (mol) Liters of Solution (L) Molarity of Solution (M) .53 .79 .78 .59 .86 .34 .88 1.8 1.0 .20 3.5 8.4 .67 .67 6.4 8.5 Conclusion Questions and Calculations, Concentration and Molarity Post-Lab Exercises 1. Adding pure water to a saturated solution (with no solids) would cause the concentration of that solution to increase / decrease / remain the same. (circle) 2. Adding pure water to a saturated solution (with some solids) would cause the concentration of that solution to initially increase / decrease / remain the same. (circle) 3. Adding a solid salt to a saturated solution causes the concentration of that solution to increase / decrease / remain the same. 4. Evaporation acting on an unsaturated solution causes the solution’s concentration to increase / decrease / remain the same. 5. Evaporation acting on a saturated solution causes the solution’s concentration to increase / decrease / remain the same. 6. Using your notes, your text, or the internet discover what happens to the saturation concentration when a solution’s temperature is increased. What happens as a solution is heated? _____________________________________________ 7. Why does this happen? (hint…think about the molecules) ___________________________________________________ 8. Can you dissolve .35 moles of Potassium Permanganate (KMnO4) into 500 mL of water? _________ Why? / Why not? (please show work) 9. Can 1750 mL of water dissolve 4.6 moles of Copper Sulfate CuSO4? _________ Why? / Why not? (please show work) 10. What is the solution concentration formed from 3.6 moles NaCl dissolved into 1.3 L of water? (please show work) 11. What is the solution concentration formed from 2.1 moles BaCl2 dissolved into 1.9 L of water? (please show work) 12. How many moles of solute are present in 1.4 L of a 1.9 M (molar) solution? (please show work) 13. What volume of water would be required to dissolve .46 moles of solute to produce a .22 M solution? (please show work) 0.67 2.5 5.0 1.0 0.46 0.5 0.40 54.4 concentration decreases molecules are moving faster No No .35mol/.5L = 0.7 M 0.480 is saturated 4.6mol/1.75L = 2.63 M 1.380 is saturated 3.6mol/1.3L = 2.77 M 2.1mol/1.9L = 1.11 M 1.4L x 1.9mol/L = 2.66 mol 0.46 mol/ 0.22mol/L = 2.09 L