Chemistry HW [12/7/11] - Mole Potpourri

Okie dokie. So, I'll do the Water table and from there you can do the rest. Row by row.

Formula or Symbol	H2O
Name of Represen tative particles	Molecules
Total number of representative Particles in one mole	6.02x1023
Mass of one mole	18.015g
GIVEN AMOUNT	130mL
Moles of given amount	7.22
Number of representative particles in given amount	4.35x1024 representative particles
Mass of Given Amount	130g

Formula Symbol: Okay, so we're dealing with Water. Everyone knows that's H₂O, if you don't then no worries; look it up on Google or something.

Name of Representative Particles: this was already filled in.

Total Number of Rep. Particles in one Mole: Okay, this is in one mole regardless. Remember Androgov's number, 6.02x10²³? Well, that's the answer.

Mass of one mole: To figure this out, you get the molar mass of the formula in question. We know water's formula is H₂O so you get the mass of two hydrogens and one oxygen like so:

H₂: 1.008x2 = 2.016g
O: 15.999
2.016 + 15.999 = 18.015g, as given in the table.

GIVEN AMOUNT: already filled in.

Moles of given amount: This is where it gets tricky. Scroll down to point number 8, where you will find that the mass of the given amount is 130. To find the amount of moles in this given amount, divide the Mass of given amount (130g) by the mass of one mole of water (18.015), which will result in approximately 7.22 moles.

Number of Representative particles in given amount: This is definitely where it gets tricky. Hearken back to the 12/6/11 HW [find it here] and recall that the Particles / Androgav's # = the amount of moles, and the moles times the formula mass = the mass of the sample. Well, we're trying to get the number of particles in the given amount, so we're gonna work backwards.

Sample Equation for easier viewing:

P/A = Mol
Mol x m_{base formula} = m_{sample amount}

For m_{sample amount} we can fill in as 130. For m_{base formula} we can fill in with 18.015. For Mol, we can fill in with 7.22. Oh, wait silly me, we've already done that! We have the moles.

So for Mol we can fill in as 7.22. For A, recall that it is androgov's or whatever his name is # which is 6.02x10²³. Working backwards, multiply 7.22 by Andy's # and you'll get something similar to 4.35x10²⁴.

Mass of given amount: This is where it gets tricky. Get the density formula, D = m/v. We know water's density is 1, and the volume (given) is 130mL. Multiple 1 by 130 to get 130g, which is in fact the mass of the given amount.