The following errors occurred when the above experiment was carried out. How would each affect the calculated molecular mass of the solute (too high,too low, no effect)? Explain your answer.
(a) The thermometer uses actually read 1.4C too high.
You must read the thermometer twice, once to determine the normal freezing point and again to determine the depressed freezing point. So if the thermometer reads too high, then it read too high each time by 1.4 degrees; therefore, the difference in delta T (delta T = Kf*m) does not change. Thus the experimental change in molality (and on into molecular mass) is not changed. That's one reason, in analytical chemistry, why we weigh by difference. Instead of weighing a sample by placing it on the pan of the balance, we measure the bottle containing the sample, remove some sample and weigh the bottle and sample again. The difference tells us how much was removed and that amount is placed in a separate container to do the experiment. Thus, if a weight is slightly off, it tends to correct itself.
We don't know which experiment you did nor how it was done unless you tell us. My crystal ball is hazy tonight.
its Molecular mass by freezing point depression. and its a pre-lab
thank you so very much.do you know the answers to these:
(b) Some of the solvent was spilled before the solute was added.
(c) Some of the solute was spilled after it weighed and before it was added to the solvent.
(d) Some of the solutions was spilled after the solute and solvent were mixed but before the freezing point was determined.
I did b in detail above. Use the same kind of reasoning on c and d. Use the same three equations I used above in answering b. d won't change the result. It just means you have less sample to determine delta T on but the molality doesn't change by spilling a drop or more after everything is mixed.
Does this affect the Calculated molar Mass?
only on Tuesdays
this site is wack
To determine the effect of this error on the calculated molecular mass of the solute, we need to understand how the thermometer reading is used in the calculation.
In order to calculate the molecular mass of a solute, we often rely on the principles of freezing point depression or boiling point elevation. By measuring the change in temperature when a solute is added to a solvent, we can determine the concentration of the solute and then use this information to calculate the molecular mass.
If the thermometer reading is actually 1.4 degrees Celsius too high, it means that the temperature recorded during the experiment is higher than the actual temperature. This would lead to an overestimation of the change in temperature caused by the solute's presence, resulting in an incorrect calculation of the solute concentration.
Since the concentration of the solute is a crucial factor in calculating molecular mass, an overestimation of the solute concentration would lead to an artificially high calculated molecular mass. Therefore, in this scenario, the calculated molecular mass of the solute would be too high.
It's important to note that the actual error in the thermometer reading does not affect the molecular mass of the solute directly. Rather, it affects the concentration determination, which then affects the calculation of the molecular mass.