Purpose: Experimental determination of standard molar volume.
Mg + 2HCl ® H2 + MgCl2
2. Collect H2 over H2O and measure volume (gas collecting tube) at room temperature.
PH2 = Ptotal – PH2O
· Mass of piece Magnesium ________________.
· Place 10-11 ml of HCl in gas collecting tube (Large test tube with graduations on it), first pour a small of amount of the 3M HCl in a small beaker than pour it into the gas collecting tube.
Bubble of H2O
Bubble of H2O at top
· Fill larger beaker to ~250ml with H2O and place under gas collecting tube.
· Insert Mg and stopper in tube tightly.
· Place a finger over hole in stopper and invert tube.
· Place the tube in the beaker of H2O, and release finger from hole while under water in the beaker. This prevents any gas from entering the gas collecting tube.
· Wait until no more gas evolves from the reaction and Mg is completely gone.
· CAREFULLY carry whole apparatus to large graduated cylinders in sinks.
· Using finger to cover hole in stopper-be sure no H2O escapes, transfer to large graduated cylinders.
· With H2O levels even inside and outside, record volume of gas. This adjusts the pressure inside the gas collecting tube to be the same as the outside air.
· Record temperature ______________.
· Record Pair __________.
· Record Volume of H2 gas (Read from gas collecting tube) __________ml. ___________ L.
Calculations and Questions