Stoichiometry of the reaction of magnesium with HCl 1. How would the following a
ID: 888569 • Letter: S
Question
Stoichiometry of the reaction of magnesium with HCl
1. How would the following affect the calculated value for the number of moles of HCL which reacted? Why?
a.) The molarity of the HCl solution was actually greater than the label indicated.
b.) The normality of the NaOH solution was lower than the label indicated.
c.) In the titration of the excess HCl solution with NaOH, the endpoint was overshot.
2. How would the following affect the calculated moles of H2 (g)? Why?
a.) The pressure of H2 was taken to be the same as the barometric pressure
b.) During the reaction, some H2 escaped the system.
c.)The thermometer used was incorrectly calibrated such that it gave temperature readings which were too high.
3. A student reacted the following unknown metal, M with HCl and collected the following data: mass of metal = 0.300 g, volume of water displaced = 227.3 mL, temp of H2 = 25 o C, barometric pressure = 760.0 torr, volume of HCl = 20.0 ml, molarity of HCl = 1.500 mol/L, and the volume of NaOH = 36.00 mL. If the metal, M had an atomic weight of 50.0 and reacted to produce MCl3, what was the molarity of the NaOH solution?
4. How would the calculated value for the number of moles of HCl reacted be affected if, unknown to the student, 1.00 M KOH instead of 1.00 M NaOH were used? Explain.
5. How would the calculated value for the number of moles of H2 produced be affected if, unknown to the student, Zn instead of Mg were used. Explain.
6. How would the calculated value for the number of moles of HCl reacted be affected if the student failed to rinse the wet buret with NaOH solution before filling it? Explain.
Explanation / Answer
1) a.The reacted HCl would increase
b. Normality = moles* nfactor = moles* 1
Therefore as the normality decreases the moles of HCl reacted would also decrease
c. Moles would increase
2)a. The calculated moles would increase
b. The calculated moles would decrease
c. The calculated moles would decrease
4) The amount of moles would remain the same
5) The amount of moles will decrease
6) The amount of moles will decrease