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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 number of protons plus the number of neutrons equals the atomic mass.
Explanation:
Atomic mass is defined as total number of protons and neutrons in the atom.
It is an average mass of an atom.
It is expressed in atomic mass unit that is a.m.u.
It is denoted with symbol 'A'.
.
Answer:
1.5M
Explanation:
Molarity = moles/volume
0.60 mol / 0.40 L = 1.5 M
The electrons begin at the lowest level, and then fills up until it reaches the highest level, and completely fills the outer shell.