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Hello!
If a sample contains 21.2 g N, how many moles of N does it contain?
0.66 mol
1.51 mol
14.01 mol
297.01 mol
We have the following data:
m (mass) = 21.2 g
MM (Molar mass of Nitrogen) = 14 g / mol
n (number of moles) = ?
Formula:

Solving:



Answer:
1.51 mol
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I Hope this helps, greetings ... Dexteright02! =)
1) Chemical reaction: HCN + H₂O → CN⁻ + H₃O⁺.
c(HCN) = 2,2 M = 2,2 mol/L.
pKa(HCN) = 9,21.
Ka = 6,16·10⁻¹⁰.
[CN⁻] = [H₃O⁺] = x.
[HCN<span>] = 2,2 M - x.
</span>Ka = [CN⁻] · [H₃O⁺] / [HCN].
6,16·10⁻¹⁰ = x² / 2,2 M -x.
Solve quadratic equation: [CN⁻] = [H₃O⁺] = 0,0000346 M.
[HCN] = 2,2 M - 0,0000346 M = 2,199 M.
2) pH = - log[H₃O⁺].
pH = -log( 0,0000346 M).
pH = 4,46.
Hydrocyanic acid and hydronium ion (H₃O⁺) are acids. Cyanide anion (CN⁻) is the strongest base in the system, cyanide anion accept protons in chemical reaction.
pKb = pKw - pKa.
pKb = 14 - 9,21 = 4,79.
Answer:
0.258 mg of iron remains.
Explanation:
To solve this problem we can use the formula
M₂ = M₀ * 
Where M₂ is the mass remaining, M₀ is the initial mass, and t is time in days.
Using the data given by the problem:
M₂ = 2.000 mg * 
M₂ = 0.258 mg
There’s no picture? regardless, if there are two numbers of electrons adding up to 8, then they will likely form an ionic bond/compound. if they can form a covalent bond with whatever amount of electrons, ex carbon 4 and 4, then it would b covalent compound