Tempurature Dependence of Salt Solubility
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I don’t understand how to make this graph...what is it supposed to look like? I’ve tried and just can’t make my computer work it...I also don’t understand what my experimental mass and official masses are supposed to be... please help!
Data: List all measurements and include proper labels.
Test tube Crystallizing Temperature (degrees C)
Solute (g/10ml) KCl NH4Cl
3.5 23.94 degrees C -----
4.0 39.69 degrees C 23.12 degrees C
4.5 57.06 degrees C 34.87 degrees C
5.0 72.22 degrees C 47.55 degrees C
6.0 --- 68.53 degrees C
Calculations/Interpretations: Show all math performed (give the formula, show your setup, and give the result. Use proper significant figures and include proper labels. Also, answer ALL questions asked in the lab.
Record your data.
Test tube
Solute (g/10ml) Solute (g/ 100ml)
3.5
4.0
4.5
5.0
6.0
Official points to plot.
Temperature (C) KCl (g/100ml) NH4Cl (g/100ml)
30 37.1 41.6
50 42.9 50.4
70 48.5 59.9
90 53.8 70.4
Plot these 4 sets of data points on a graph:
1. Experimental KCl solubility
2. Experimental NH4Cl solubility
3. Official KCl solubility
4. Official NH4Cl solubility
Plot temperature (deg C) on the Y-axis (vertical) and solubility (g/100ml) across the X-axis (horizontal).
The temperature range should be from 0 to 100 deg C. The solubility range should be from 0g/100ml to 100 g/100ml.
From Graphs:
KCl NH4Cl
Experimental mass at 60 C:
Official mass at 60 C:
% difference:
(a) Why is it important to not allow the test solutions to boil?
It would be a poor variable to cause a change the volume of the solution, boiling would alter this far more than evaporation from an 80 degree solution.
(b) Why is it better to determine the initial crystallization temperature during cool down rather than the temperature at which all of the salt dissolves?
It is harder to see the point at which all the salt has dissolved and it dissolved through agitation as well as increase in temperature, i.e. as you would warm it up it doesn't all dissolve for the saturation point of that temperature immediately. It is far easier to note the crystallization point when cooling.
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Solution Summary
This solution explains how to solve severla problems dealing with temperature dependence of salt solubility.
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