The purpose of this lab is to observe the reaction between hydrochloric acid and magnesium metal. When the substances are reacted over water, the products produced are a salt in aqueous solution and a gas. While the salt remains in the water as part of a solution, the gas produced will float to the top. Though water vapor pressure will affect the pressure of the gas in the eudiometer, it is possible to apply Dalton’s law of partial pursues to find the dry pressure of the gas. When the dry pressure is determined, the volume of the gas at STP can then be determined and what the experimental volume of one mole of the gas would be at STP.
1. Put on the necessary safety gear, including safety goggles and a lab coat/apron.
2. Cut a piece of magnesium
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The equation for this reaction tells that for every mole of magnesium reacted, the amount of hydrogen gas produced will also be one mole. Looking at just the first trial, after the 0.0388 g of magnesium was finished reacting in an excess of hydrochloric acid, the amount of gas produced was 42.7 mL. The number of moles of magnesium reacted, which is the same as moles of hydrogen produced, was 0.00160 moles, found by dividing the mass of magnesium by its molar mass. This, along with the temperature and pressure of the room, could them be used to find the volume of gas at STP; however, this only after taking into account the water vapor pressure in the eudiometer, which is by 23.8 was subtracted from the barometric pressure of the room. Using the combined gas law, the calculated volume of the gas at STP would be 0.0377 liters. If one wanted to find the volume of mole this gas at STP, then all that is required is to divide the 0.0377 liters at STP by the original number of moles of magnesium from the start of the experiment; this would yield the results at STP if one mole of magnesium was reacted, which is the same as one mole of hydrogen produced according to the chemical equation. In the end, the volume of mole of the hydrogen gas produced in this experiment would be equal to 23.6 …show more content…
7. Would changing the molarity of the hydrochloric acid affect the final results? Explain.
No, changing the molarity of the hydrochloric acid would not affect the results, since in this experiment, the Mg was the limiting reactant, not the HCl. So as long as there is enough HCl in the solution to react completely with the magnesium, the results should not change. However, if there is not enough hydrogen with a lower molarity, then the experiment will produce less hydrogen gas since not all the magnesium will be completely reacted.
8. How does Avogadro 's hypothesis relate to the results obtained in this experiment?
Since the two trials of the experiment are done at a constant pressure and temperature, and about the same amount of moles of gas were produced, it makes sense that the volumes are around the same amount to. This also relates to the accepted value used for this experiment, which was 22.4 L at STP; with Avogadro’s hypothesis in mind, it makes sense that the put hypothetical volume calculated was around this value for one mole of