Calculating Charge on 1 g N3- Ions: Where Did I Go Wrong?"

[Alioth]

Homework Statement

What is the charge in coulomb on 1 gram of N3- ions

2. The attempt at a solution
the atomic mass of nitrogen is 14 gram.
hence 14 g nitrogen will contain 6.022*10^23 ions.
therefore 1 g nitrogen will contain n=6.022*10^23/14 no. of ions.
one N3- ion has a charge of q=4.8*10^-19 C.
so n ions of N3- will carry a charge of n*q C= 2.065*10^4 C
But this answer is wrong. Where am I going wrong?
Does 14 g nitrogen contain Avogadro's no. of atoms?

 

[Curious3141]

Homework Statement

What is the charge in coulomb on 1 gram of N3- ions

2. The attempt at a solution
the atomic mass of nitrogen is 14 gram.
hence 14 g nitrogen will contain 6.022*10^23 ions.
therefore 1 g nitrogen will contain n=6.022*10^23/14 no. of ions.
one N3- ion has a charge of q=4.8*10^-19 C.
so n ions of N3- will carry a charge of n*q C= 2.065*10^4 C
But this answer is wrong. Where am I going wrong?
Does 14 g nitrogen contain Avogadro's no. of atoms?

Homework Statement

Homework Equations

The Attempt at a Solution

The atomic mass of N is 14Da (it is NOT 14g!). But the molecular mass of N₃^- is 14*3 = 42Da.

Another mistake: the charge on one N₃^- ion is just e (a single electron charge).

Hence your answer overestimates by a factor of 9.

 

[Borek]

Lousy typing gives lousy results. N₃^- and N^3- are different things.

 

[Curious3141]

Lousy typing gives lousy results. N₃^- and N^3- are different things.

Very good point. He has to clarify if he meant nitride or azide (I assumed the latter).

 

[Strawberry1711]

Your solution is right but the question you ask for might be for 1 g-ion.

• 1 g-ion = (weight in grams of sum of atomic weight of atoms making the ion.)
• Here N^3- has 14 amu so 1g-ion 14 gm.
• So here we have to find for 14g that is 1mole of nitride ion.

1 ion of nitride has =1.6 ×10^-19 × 3 C
Therefore 6.022 × 10^23 ions has = 6.022 × 10^23 ×1.6 ×10^-19 × 3 C = 2.89 × 10^5 C.

 

[Borek]

Welcome to the PF @Strawberry1711 - just in case, please read the forum rules.

6.022 × 10^23 ×1.6 ×10^-19 × 3 C = 2.89 × 10^5 A.
I hope that helps...

Stating that Coulomb equals Ampere definitely doesn't help. These are two different units.

 

[Strawberry1711]

Sorry
@Borek
It's 2.89 × 10^5 C.
And Thank you for telling me that I have corrected it.