Given:3.40g sample of the steel used to produce 250.0 mLSolution containing Cr2O72−
Assuming all the Cr is contained in the BaCrO4 at the end.
(0.145 g BaCrO4) / (253.3216 g BaCrO4/mol) x (250.0 mL / 10.0 mL) x (1 mol Cr / 1 mol BaCrO4) x (51.99616 g Cr/mol / (3.40 g) = 0.219 = 21.9% Cr
Answer:
pH = 9.48
Explanation:
We have first to realize that NH₃ is a weak base:
NH₃ + H₂O ⇔ NH₄⁺ + OH⁻ Kb = 1.8 x 10⁻⁵
and we are adding this weak base to a solution of NH₄NO₃ which being a salt dissociates 100 % in water.
Effectively what we have here is a buffer of a weak base and its conjugate acid. Therefore, we need the Henderson-Hasselbach formula for weak bases given by:
pOH = pKb + log ( [ conjugate acid ] / [ weak base ]
mol NH₃ = 0.139 L x 0.39 M = 0.054 mol
mol NH₄⁺ = 0.169 L x 0.19 M = 0.032 mol
Now we have all the information required to calculate the pOH ( Note that we dont have to calculate the concentrations since in the formula they are a ratio and the volume will cancel out)
pOH = -log(1.8 x 10⁻⁵) + log ( 0.032/0.054) = 4.52
pOH + pH = 14 ⇒ pH = 14 - 4.52 = 9.48
The solution is basic which agrees with NH₃ being a weak base.
The expected radius of a nucleus having 82 protons and 125 neutrons would be 5.2 fm.
<h3>
What is a nucleus in the atom?</h3>
The nuclei are incredibly tiny and dense. They are 10 thousand times smaller than an atom and have more than 99.9% of their mass. Protons, which have a positive charge, and neutrons, which have no electrical charge, make up the nucleus. Alternately, protons and neutrons make up an atom's nucleus. While neutrons have no charge but weigh the same as protons, protons have a positive charge that is equivalent to the orbiting electrons. Based on the 1909 Geiger-Marsden gold foil experiment, Ernest Rutherford identified the atomic nucleus in 1911, which is the compact, dense region made up of protons and neutrons at the heart of an atom.
To learn more about the nucleus, visit:
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A chemist is using a solution of HNO₃ that has a pH of 3.75. what is [H⁺] for the solution is 1.7 × 10⁻⁴M.
<h3>How do we calculate the [
H⁺]?</h3>
Concentration of H⁺ ion will be calculated by using the below equation of pH as:
pH = -log[H⁺]
or [H⁺] = 
Given that, pH = 3.75
So concentration of H⁺ ion will be calculated as:
[H⁺] = 
[H⁺] = 1.7 × 10⁻⁴M
Hence concentration of H⁺ ion is 1.7 × 10⁻⁴M.
To know more about pH & [H⁺], visit the below link:
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