I'm going over some post-laboratory questions for Conductivity of Solutions.
One of the questions is...
From your measurements, what can you say about
a) the presence of ionic impurities in tap water?
b) the presence of molecular impurities in tap water?
I measured the conductance of deionized water to be 0.00 mS and the conductance of tap water to be 0.20 mS.
What kind of an answer is this question looking for?
Ah, conductivity of solutions, a classic topic! Let me assist you with a touch of humor.
a) From your measurements, the nonzero conductance of tap water compared to the zero conductance of deionized water indicates the presence of ionic impurities in tap water. Well, well, it seems that tap water is sneaking in some extra guests!
b) Now, when it comes to molecular impurities, they are a bit shyer than their ionic buddies. Sadly, conductivity measurements cannot directly tell us about the presence of molecular impurities in tap water. These molecules may be present, but they may not be electrically charged party animals like the ions.
So, to sum it up, your measurements are suggesting that tap water includes some ionic impurities, but we can't directly determine the presence of molecular impurities using conductivity alone. Keep in mind; these impurities might just be having their own little aquatic shenanigans!
For the question on the presence of impurities in tap water based on your conductance measurements, you can make the following observations:
a) The presence of ionic impurities in tap water: Since tap water conducts electricity and has a conductance value of 0.20 mS, it indicates the presence of ionic impurities. Ionic impurities are charged particles that can carry an electric current, and their presence in tap water allows it to conduct electricity.
b) The presence of molecular impurities in tap water: To determine if there are molecular impurities in tap water, you would need a comparison with deionized water. Deionized water is purified and expected to have little to no impurities. In your case, the conductance of deionized water measured at 0.00 mS suggests that it does not contain any ionic or molecular impurities capable of conducting electricity. Comparing this to the conductance of tap water at 0.20 mS, it indicates that tap water likely contains molecular impurities that can conduct electricity.
In summary, based on the conductance measurements, you can conclude that tap water contains both ionic and molecular impurities, whereas deionized water does not.
This question is asking you to analyze the conductance measurements of deionized water and tap water and infer the presence of ionic and molecular impurities in tap water based on those measurements.
To answer this question, you need to understand the concept of conductance. Conductance is a measure of the ability of a substance to conduct electric current. In aqueous solutions, the conductance is primarily due to the presence of ions. Therefore, if a solution has higher conductance, it signals the presence of ionic impurities.
Now, let's address each part of the question:
a) The fact that tap water has a conductance of 0.20 mS suggests that it contains ionic impurities. This is because tap water has a higher conductivity compared to deionized water, which has a conductance of 0.00 mS. The presence of ionic impurities can arise from dissolved salts or other ionic compounds in the tap water.
b) The question also asks about the presence of molecular impurities in tap water. Molecular impurities are non-ionic substances that do not dissociate into ions in solution. Since the conductance measurements are primarily affected by the presence of ions, it is difficult to directly infer the presence of molecular impurities based on these measurements alone. To determine the presence of molecular impurities, you would need to perform additional tests or analysis specific to the molecular compounds of interest.
In summary, based on the given measurement values, you can conclude that tap water contains ionic impurities since it has a higher conductance compared to deionized water. However, the conductance measurements alone do not provide direct information about the presence of molecular impurities in tap water.
How large a number do you think 0.20 mS is (compare it with some of the measurements you made). The conductance is related to the number of ions in solution. That should be an indication of the number of ions in tap water.
For the second question, I don't think conductance measurements will tell you anything about the molecular composition since those molecules don't give you conductance (at least not unless they react with water). For example, remember that CO2 is a molecule and that reacts with water to produce a small amount H2CO3 which then ionizes VERY slightly to provide H^+ and HCO3^- ions. My answer to that part, I guess, would be "conductance measurements will not indicate information about the molecular composition materials dissolved in H2O unless the molecule reacts with water to form ions."