The mass of an erlenmeyer flask is 78.639g and the mass of the flask and water is 327.039. If the density of water is 1 g/ml then what is the true volume of the flask?
so i had subtracted the mass of just the flask from the mass of the flask and the water and got 248.4. Would that be the amount of the volume in mL? Can you do the calculation for me so I can better understand this because i need to do something so that grams are cancelled out but that would involve doing 1/248.4 which doesn't make any sense when I have to use this calculation to do a different calculation regarding trying to find the molar mass of a liquid?
Also, why is it that one can use the ideal gas law to obtain the molar mass for a liquid since it only applies to gases that act under ideal circumstances. Is it because the liquid is turned into vapor anyways and the mass of the condensed vapor is equal to the mass of the gas? Can anyone explain this?
First part. You have subtracted correctly and MASS of the water in the flask is 248.4 grams. Then since
mass = volume x density you can rearrange that to volume = mass/density
mass = 248.4g and density of the H2O is 1 g/mL (from the problem), then
248.4g/1 g/mL so volume is 248.4 mL. In this case the volume and the mass have identical values BECAUSE the density is 1 g/mL but if the density were any other value than 1g/mL the volume and mass would not be the same.
For the second part, I assume this is a follow up to your earlier post. Again, I'm not exactly sure of the experimental details but I think the liquid is supposed to evaporate and fill the flask with the vapor. As a vapor, the ideal gas law allows you to calculate the molar mass. Of course, you assume the gas is an ideal gas to do this.
To find the true volume of the flask, you can subtract the mass of just the flask from the mass of the flask and water, as you correctly did. However, to convert the resulting mass value to volume in milliliters (mL), you need to consider the density of water.
The calculation you mentioned, 1/248.4, does not give you the volume in mL because 248.4 is the mass, not the density. To find the volume, you need to divide the mass by the density of water.
The formula for density is:
Density = Mass / Volume
Rearranging the formula, we have:
Volume = Mass / Density
In this case, the mass is 248.4 g and the density of water is 1 g/mL. So, the volume can be calculated as:
Volume = 248.4 g / 1 g/mL
Volume = 248.4 mL
Therefore, the true volume of the flask is 248.4 mL.
Regarding your question about using the ideal gas law to obtain the molar mass of a liquid, usually, the ideal gas law (PV = nRT) applies to gases. However, under certain conditions, liquids can also behave like ideal gases. This occurs when the liquid is converted into vapor and the conditions meet the assumptions of the ideal gas law.
When a liquid turns into vapor, it expands and fills a larger volume. This expansion follows the ideal gas behavior and allows us to use the ideal gas law. The mass of the condensed vapor is equal to the mass of the original liquid since it is just a different phase of the same substance.
By measuring the pressure, volume, and temperature of the vapor, we can use the ideal gas law to calculate the number of moles (n) of the vapor. And since the number of moles of the vapor is equal to the number of moles of the original liquid, we can determine the molar mass of the liquid using the mass and moles of the vapor.
So, the use of the ideal gas law to obtain the molar mass of a liquid relies on the conversion of the liquid into vapor and the application of the ideal gas behavior during that phase transition.