Molar Volume of Gas

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Introduction

The objective of this experiment is to combine Magnesium (Mg) with hydrochloric acid (HCl) to determine the molar volume of hydrogen gas (H2) (converted to the molar volume at STP) and then, to compare obtained results with the molar volume of an ideal gas. To determine the measured molar volume of hydrogen gas, we are going to use this equation: The molar volume of the ideal gas will be determined by the equation , where T = 237 K, P = 101.3 kPa. The hydrogen gas will be collected as a product of chemical reaction where Magnesium reacts with hydrochloric acid and produces magnesium chloride with hydrogen gas. Mg(s) + 2HCl(aq) MgCl2(aq) + H2(g)

From this equation we can conclude that the mass of hydrogen is stoichiometrically related to the mass of magnesium. To determine the partial pressure of the gas we might use the Dalton’s Law of Partial Pressures, where and are laboratory pressures.

The corresponding STP molar volume now can be obtained from the Law of Gases, , and the result can be compared with the ideal gas value.

Pos-Laboratory Questions:
1.
i) Mg is limiting, all Mg will be gone.
ii) Some Mg will stay, since it didn't react completely.
2. Following my calculations (#5), we can conclude that the V1 is roughly equal to the V2. And this is exactly what the Avogadro hypothesis says.

Conclusion:
By doing this experiment we record the necessary data and it was used to determine the standard molar volume of hydrogen gas. The observed molar volume has been compared to an ideal gas. By comparing the two volumes the percent error has been determined -3.57%. This error could be obtained because of the uncertainty in measurements and the use if only three significant figures in calculations. While this experiment, the Avogadro’s fundamental hypothesis has been proved.
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