[supehr]

For 2.c) i got an answer of 3182.47 mm.

I first converted 142 ft -> mm.
Then i did the following:
h_hg x d_hg = h_h20 x d_h20
and solved for the height of the mercury column.
and i got an answer to be 3182.47 mm =3182.47 mmhg

(oops i posted in the wrong forum i meant to post it in the undergrad general chem forum)

[Borek]

I have not checked the numbers itself, but the approach looks sound.

Note: you are mixing units, you express height of the column in mm and - most likely - densities in g/cm³. In this case it doesn't matter as these units cancel out, but unless you made it knowing what you are doing, this is a risky approach, as it not always clear what are the units of the answer.

[curiouscat]

Seems right. I get the same answer.

[curiouscat]

Note: you are mixing units, you express height of the column in mm and - most likely - densities in g/cm³. In this case it doesn't matter as these units cancel out, but unless you made it knowing what you are doing, this is a risky approach, as it not always clear what are the units of the answer.

Agree. OTOH practically it's often easy / fast to work with hybrid units rather than convert everything to a consistent system.

The risk of messing up is there but one way out is to explicit track & cancel units. That seems to work fine.