Chloe LambertStephensonHonors Chemistry, Period 325 January 2018Molar Relationships Inquiry lab Conclusion Using empty plastic bags, a periodic table, and an electronic balance my group was able to determine the identities of six sealed bags of unknown compounds labeled with the number of moles of powder contained in each bag.
We found the molar mass of each of the given compounds using the periodic table. To do this we added the atomic mass of the quantity of each element in the given formula.Molar Masses of Given Compounds:Compound NameSodium carbonateSodium chlorideSodiumbromidePotassium chlorideSodiumiodideSucroseSodium bicarbonateFormulaNa2CO3NaClNaBrKClNaIC12H22O11NaHCO3Molar Mass (in grams)106g58.4g102.9g74.6g150g342g84g Secondly, we weighed each bag of unknown compounds separately. Then we weighed an empty plastic bag, so we could subtract the empty bag weight from the weight of the unknown compound in order to get an accurate measurement of each substance.
From there, we divided the weight of each unknown compound by the total number of moles labeled on the bag to find the molar mass. To identify the unknown compounds we compared the known compounds molar mass with the unknown compounds molar mass.We conducted our experiment this way because when followed correctly it produces the data needed to find the identity of the unknown substances. Error that may have occurred would have been a result of improper weighing such as not letting the balance reset all the way to zero before placing the bagged substance onto the scale. Any lab members putting their body weight onto the lab table could also result in an inaccurate mass being recorded. Miscommunication is also a factor to consider when conducting a lab. Our group did not have any known error.
Final Results:Compounds in BagsMoles Labeled on BagWeight of Unknown – Weight of Empty BagWeight of Unknown/Number of MolesType of CompoundUnknown A1.22mol71.17g58.
336g/molSodium chlorideUnknown B.618 mol51.91g83.997g/molSodium bicarbonateUnknown C.182 mol62.09g341.154g/molSucroseUnknown D.
289 mol30.57g105.779g/molSodium carbonateUnknown G.
464 mol34.54g74.440g/molPotassium chlorideUnknown F.273 mol28.
1g102.930g/molSodium bromideThe results of our experiment demonstrate how we were able to identify unknown substances after undergoing a series a calculations. Determining the molar mass led us to the number of moles of an element that were in our sample. Since the molar mass is equal to the total mass of an element present in one mole of that element, we were able to divide the mass of each bag by the number of moles to determine the molar mass. The molar masses that we determined from the given formulas allowed us to easily match up the compounds to their unknown using the results depicted in the data table.
I have found that The Prentice Hall Chemistry textbook supports my lab groups data with its statement ” to calculate the molar mass of a compound, find the number of grams of each of each element in one mole of the compound. Then add the masses of the elements in the compound”(Wilbraham 295). This shows that my group was able to identify the unknown compound using a suitable method. Following this tested procedure was a correct choice and gave us the most accurate results. This is just one method to solve the issue that we were presented with, it may not be the quickest method but it was successful in discovering the identities of the unknown compounds.Works CitedWilbraham, Staley, Matta, and Waterman.
(2007). Prentice hall chemistry. Boston, Massachusetts: Pearson prentice hall.