Calculating Molar Volume of H2 Gas at STP with Mg Ribbon | Chemistry Question

[courtrigrad]

Lets say you want to find the molar volume of a gas ($$H_{2}$$ specifically). So you basically use a $$Mg$$ ribbon and find the volume of the $$H_{2}$$ gas in a test tube with the $$Mg$$ ribbon. The water fizzes and bubbles. I am having trouble finding the volume of $$H_{2}$$ at STP. I used the formula: $$V_{1} = \frac{P_{1}}{T_{1}} \times \frac{T_{2}}{P_{2}}$$. After plugging in experimental values I got 1.234. Does this make sense? What units is this in. To find the molar volume I know that I do the moles of H_2 gas divided by the volume of H_2 gas. Does it make sense to only have 0.0025 moles of H_{2} gas reacted? Because I se a Mg strip that was 1.20 grams.

Any help is appreciated

Thanks

 

[QuantumMech]

Is that the combined gas equation?

$$\frac{p_{1} V_{1}}{T_{1}} = \frac{p_{2} V_{2}}{T_{2}}$$

Molar volume is the gas' volume divided by the moles of gas.

 

[thepatientmental]

for sharing your question and experiment! It sounds like you are on the right track in using the ideal gas law (PV = nRT) to calculate the molar volume of H2 gas at STP. The formula you used, V1 = (P1/T1) x (T2/P2), is a rearranged version of the ideal gas law where V1 represents the initial volume of the gas, P1 and T1 represent the initial pressure and temperature, and P2 and T2 represent the final pressure and temperature.

The units for V1 in your calculation would depend on the units used for pressure and temperature. If you used standard units of pressure (atm) and temperature (K), then the volume would be in liters (L).

It is possible to have a small amount of moles of gas reacted, as in your case with 0.0025 moles of H2. This can happen if the reaction is not complete or if there are other factors affecting the amount of gas produced. However, it is important to make sure that your experimental values are accurate and that all measurements were taken correctly.

In order to accurately determine the molar volume of H2 gas at STP, it would be helpful to repeat the experiment multiple times and take the average of the results. This can help account for any errors or inconsistencies in the data. Additionally, make sure to use the correct molar mass for H2 (2.016 g/mol) when calculating the moles of gas reacted.

I hope this helps and good luck with your experiment!