Answer:
Its mass is about the same as that of a proton
Explanation:
He can conclude that his experiment has very low precision.
<h3>What is Precision ?</h3>
Precision is defined as the degree of refinement with which an operation is performed or a measurement .
Precision is how close the exact answers are together.
As, the answers are increasing in time.
None of the answers are similar to one another.
Hence, He can conclude that his experiment has very low precision.
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The molarity of the hydrogen peroxide solution from the information supplied in the question is 12.26 M.
Co = 10pd/M
Where;
Co = concentration = ?
p = percent of the hydrogen peroxide = 30%
d = Density of hydrogen peroxide = 1.39 g/ml
M = Molar mass = 34 g/mol
Substituting values;
Co = 10 × 30 × 1.39/34
Co = 12.26 M
The molarity of the hydrogen peroxide solution from the information supplied in the question is 12.26 M.
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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
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