Hello!
the correct setup is shown at bottom of your question
we get
total moles*(1/102.0 g/mol)= total grams Al2O3
hope this helps. any questions please ask. thank you kindly
Nitrate ions
and potassium ions
.
<h3>Explanation</h3>
Potassium dichromate undergoes a double-decomposition reaction with barium nitrate to produce barium dichromate and potassium nitrate. The reaction is possible due to the low solubility of barium dichromate that precipitate out of the solution readily after its production.
Start with the balanced chemical equation for this process:

Rewrite the chemical equation as an ionic one; express all soluble salts- those with state symbol (aq)- as their constituting ions while leaving the insoluble (s) intact.

and
are found on both sides of the equation by the same quantity. The two ions thus took no part in the net reaction and act as spectator ions.
Answer: 2mg
Part per million is unit that equal to mg/kg of water or simply

. In this case, you asked how much NaCl needed and know the volume of water(100mL), concentration(20ppm or 20 mg/kg) and water density.
Then, the equation would be
concentration = NaCl weight/ water weight
20 x

mg= NaCl weight/ (100ml x 1g/ml)
NaCl weight= 20x

mg/kg x 100g
NaCl weight= 2000 x

g
NaCl weight= 2x

g = 2mg