PLEASE HELP!!
2 answers:
You might be interested in
The given question is incomplete. The complete question is as follows.
A solution contains an unknown mass of dissolved barium ions. When sodium sulfate is added to the solution, a white precipitate forms. The precipitate is filtered and dried and then found to have a mass of 212 mg. What mass of barium was in the original solution? (Assume that all of the barium was precipitated out of solution by the reaction.)
Explanation:
When and
are added then white precipitate forms. And, reaction equation for this is as follows.
It is given that mass (m) is 212 mg or 0.212 g (as 1 g = 1000 mg). Molecular weight of is 233.43.
Now, we will calculate the number of moles as follows.
No. of moles = mass × M.W
=
= 0.00091 mol of
Hence, it means that 0.00091 mol of . Now, we will calculate the mass as follows.
Mass = moles × MW
=
= 0.124 grams or 124 mg of barium
Thus, we can conclude that mass of barium into the original solution is 124 mg.
Answer : The correct option is, (B) Salicylic acid
Solution :
First we have to calculate the moles of salicylic acid and acetic anhydride.
Now we have to calculate the limiting and excess reagent.
The balanced chemical reaction is,
From the balanced reaction we conclude that
As, 2 moles of salicylic acid react with 1 mole of acetic anhydride
So, 0.507 moles of salicylic acid react with mole of acetic anhydride
The excess of acetic anhydride = 0.783 - 0.2535 = 0.5295 moles
That means the in the given balanced reaction, salicylic acid is a limiting reagent because it limits the formation of products and acetic anhydride is an excess reagent.
Hence, the limiting reagent is, salicylic acid.