Fundamental Units?

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somyapanchal1D
Posts: 34
Joined: Mon Jun 17, 2019 7:23 am

Fundamental Units?

Postby somyapanchal1D » Thu Jun 27, 2019 7:12 am

In a lot of the homework problems we were asked to calculate the fundamental units of different molecular compounds. What exactly are fundamental units and how do you solve for them? Here is an example problem from Fundamentals E.25:

(a) Determine the number of KNO3 formula units in 0.750 mol KNO3.
(b) What is the mass (in milligrams) of 2.39*10^20 formula units of Ag2SO4?
(c) Estimate the number of NaHCO2 formula units in 3.429 g of NaHCO2, sodium formate, which is used in dyeing and printing fabrics.

Leah farhadi 1F
Posts: 36
Joined: Mon Jun 17, 2019 7:23 am

Re: Fundamental Units?

Postby Leah farhadi 1F » Thu Jun 27, 2019 9:57 am

I think formula units means the actual number of atoms, ions, or molecules in a sample, it is just formally called formula units for the molar mass (mass per mole of its formula units) of an ionic compound.

For example, we use avogadro's constant in order to figure out how many atoms are within some mol of a compound =>
Mass of sample = amount in moles x mass per mole

E.25: a) (0.750 mol)x(6.022x10^23 formula units.mol^-1) = 4.52 x 10^23 formula units

D-nice1D
Posts: 19
Joined: Fri Sep 28, 2018 12:21 am

Re: Fundamental Units?

Postby D-nice1D » Thu Jun 27, 2019 10:12 pm

Can we use (write out) formula units instead of actually writing the units or will points be deducted?


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