# Hydrogen Gas Lab Essay

Sorry, but copying text is forbidden on this website!

* For the mass, an uncertainty of0.01g was used, as the uncertainty was stated on the weighing machine.

* For the volume, an uncertainty of0.05mL was used, as it was half the smallest increment on the graduated cylinder.

* For the temperature, an uncertainty of0.5 was used, as it was half the smallest increment on the thermometer.

Sample Calculation

Converting mL to L

Data Processing:

Magnesium+HCl Reaction

-Finding the molar volume at STP of hydrogen gas when HCl is reacted with magnesium.

Finding Pressure of

(Pressure of H2O at 21=0.02763)

Finding Volume of at STP

0.002

Sample Calculation

Finding Uncertainty for

Finding moles of

Moles of

Finding Molar Volume of at STP.

Zinc+HCl Reaction

– Experimentally calculating molar mass of zinc using the ideal gas laws.

Finding Pressure of

(Pressure of H2O at 21=0.02763)

Finding Moles of

Determining Molar Mass of Zn

Conclusion:

In conclusion it was found that the molar volume of hydrogen gas that was produced when hydrochloric acid reacted with magnesium was 19L/mol3. Ideally it should be 22.4L/mol according to the ideal gas laws. There is a percent difference of 15% between the two values. But if uncertainties are considered the percent difference is reduced to 2%. This is an acceptable value because the actual value of 22.4L/mol is an approximation in ideal conditions according to the ideal gas laws. The ideal gas laws don’t take into consideration the attractive forces between atoms, or the volume of the atoms. And most likely if those factors were considered then the percent difference would be 0%.

For the second part of the experiment it was experimentally found using the ideal gas laws that the molar mass of zinc is 124 g/mol. When compared with the actual value of 65g/mol, there is a percent difference of 90%. And even if uncertainties are considered, the percent difference is only reduced to 64%. This is too big; therefore the data is rendered unreliable.

There were quite a few weaknesses and limitations in this lab. First of all the volume of H2O mixed in with the H2 gas was not considered. Had it been considered, then the volume found at STP would have been lower, and it would give a more accurate measurement to what the experimental value is. Another weakness in this lab was the fact that the molar mass of zinc was twice as big as its accepted value. The most likely reason for this is that when the zinc reacted, it is likely that some of the hydrogen gas was not in the beaker, but the hydrogen gas escaped into the air.

That is why when the formula n=PV/RT was used, the volume in the numerator was half as big as it should be, which in turn caused the calculated molar mass to double. So it can be assumed that approximately half the hydrogen gas escaped into the air. Another weakness was the fact that the apparatus was left over night, and so if there was a microscopic hole or crack, then the chances of the hydrogen escaping is very high. This would be true because, and since hydrogen has the lowest molar mass of all the elements, it would have a very high velocity, and so it is possible that the hydrogen gas was able to escape through a microscopic hole at a fast rate because it has such a high velocity. Not only that, but since it was left overnight, it would have had more time to escape the beaker.

There are a number of ways that this lab could be improved. First of all, a new graduated cylinder should be used to ensure that there are no cracks or holes through which the hydrogen gas can escape. Along with that the apparatus should not be left out overnight, but instead the reaction should be speeded up by heating up the apparatus, and then taking the measurements of the volume of gas every 1 minute. This in turn would decrease the amount of energy lost to the environment, and it would end up giving more accurate results.

Next time, the volume of should also be considered. A percentage value can be used, since we know the pressure that gives, that pressure can be converted into a percent, and multiplies by the total volume, and then inversed. This in turn will in turn give the volume of .This will hold true because V=nRT/P, so pressure and volume are inversely proportional, and since nRT is a constant V and P have to change accordingly.