In a balanced chemical equation, the numbers of individual particles and the numbers of moles of particles are represented by the COEFFICIENTS.
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Exothermic is the right answer my friend
The mass of ammonium chloride that must be added is : ( A ) 4.7 g
<u>Given data :</u>
Volume of water ( V ) = 250 mL = 0.25 L
pH of solution = 4.85
Kb = 1.8 * 10⁻⁵
Kw = 10⁻¹⁴
Given that the dissolution of NH₄Cl gives NH₄⁺⁺ and Cl⁻ ions the equation is written as :
NH₄CI + H₂O ⇄ NH₃ + H₃O⁺
where conc of H₃O⁺
[ H₃O⁺ ] = 
and Ka = Kw / Kb
∴ Ka = 5.56 * 10⁻¹⁰
Next step : Determine the concentration of H₃O⁺ in the solution
pH = - log [ H₃O⁺ ] = 4.85
∴ [ H₃O⁺ ] in the solution = 1.14125 * 10⁻⁵
Next step : Determine the concentration of NH₄CI in the solution
C = [ H₃O⁺ ]² / Ka
= ( 1.14125 * 10⁻⁵ )² / 5.56 * 10⁻¹⁰
= 0.359 mol / L
Determine the number of moles of NH₄CI in the solution
n = C . V
= 0.359 mol / L * 0.25 L = 0.08979 mole
Final step : determine the mass of ammonium chloride that must be added to 250 mL
mass = n * molar mass
= 0.08979 * 53.5 g/mol
= 4.80 g ≈ 4.7 grams
Therefore we can conclude that the mass of ammonium chloride that must be added is 4.7 g
Learn more about ammonium chloride : brainly.com/question/13050932
Answer:
a. ionic, 211.62g/mol
b. molecular, 149g/mol
c. molecular, 342g/mol
Explanation:
Ionic Compound: These are compounds (2 or more elements) where atoms of the element have lost or gained electrons, thus they are ions, thus the name ionic. An easy way to identify ionic compounds is to see if there are any metals. Metals tend to give up their electron to a non-metal. It maybe helpful to familiarize which parts of the periodic table have metals and non-metals.
Molecular Compounds: These are compounds (2 or more elements) that are neutral. An easy way to identify them is that the compound is made up of just non-metals.
Molar Mass is the masses of each individual element in the compound. Refer to the periodic table for the masses and add them up carefully, remember to multiply their mass based on how many molecules there are in the compound, like for a, we can find the mass of NO3, but we need to multiply it by 2 since we have 2 molecules of NO3.
a. Sr(NO3)2
Sr= 87.62
NO3= 14 + (3 x 16)= 62
Sr + 2 (NO3)
87.62 + (2 x 62)= 211.6
b. (NH4)3PO4
NH4= 14 + 4 = 18
PO4= 30.97 + (4 x 16)= 94.9
(NH4 x 3) + PO4
(18 x 3) + 94.9 = 149
c. C12H22O11
(12 x C) + (22 x H) + (11 x O)
(12 x 12) + (22 x 1) + (11 x 16)
144 + 22 + 176= 342
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