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Leto [7]
2 years ago
9

A fire is an example of an exothermic reaction. Which of the following best

Chemistry
1 answer:
Juliette [100K]2 years ago
8 0

Answer: B. Fire is releasing energy

Explanation:

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Will the ph of a solution of nh4cn be >7, <7, or =7?
never [62]
PH of a solution will be <span>higher than 7
</span>
Ammonium cyanide is a salt formed by hydrogen cyanide and ammonia. Ammonia is a weak base and hydrogen cyanide is a weak acid. 
NH₄CN + H₂O ⇒ NH₃ + HCN 

NH₄⁺ + H₂O -----> H₃O⁺ + NH₃

CN⁻ + H₂O -----> HCN + OH⁻ 

Although both compounds are weak electrolytes, NH₃ is somewhat stronger base than HCN is a strong acid, so the solution reacts alkaline. We can prove this using Ka and Kb values:

Ka(HCN) = 4.9 x × 10⁻¹⁰

Kb(NH₃) = 1.8 × 10⁻⁵<span>
Kw= </span>1.0 × 10⁻¹⁴

Let's first calculate Ka for NH₄⁺: 
Ka(NH₄⁺) x Kb(NH₃<span>) = pKw

</span>Ka(NH₄⁺) = Kw/Kb(NH₃) = 5.6 x 10⁻¹⁰

Then, Kb for CN⁻:

Kb(CN⁻) x Ka(HCN) = pKw

Kb(CN⁻) = Kw/Ka(HCN) = 2 x 10⁻⁵

 
From this, we can see that the acid constant NH4⁺ is much lower than the base constant of CN⁻, which will say that the solution of NH₄CN will react slightly alkaline because of the higher presence of hydroxyl ions in solution.


7 0
3 years ago
What about this one y'alllll
densk [106]

Answer:

um.. is this a quiz or what girl...

6 0
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How many grams are equivalent to 1.80x10-4 tons?
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Do you want the estimated answer or the exact answer?

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C

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the enthalpy of reaction is independent of the reaction path

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