How many particles are present in a 56.9 mole sample of calcium hydroxide?
1 answer:
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The 0.05 moles of required to make 1 L of solution in which the
concentration is 0. 15 M.
Calculation,
The Sodium phosphate dissolves as follows:
→
To make 1. L of solution in which the concentration is 0. 15 M
The morality of = 0.15 M = number of moles / volume in lit
The morality of = 0.15 M = number of moles /1 Lit
number of moles of = 0.15 mole
The mole ratio is 1: 3
It means, the 1 mole of required to form 3 mole of
So, to form 0.15 mole of = 1×0.15 / 3 moles of
required.
Hence, number of moles of required = 0.05 moles.
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Answer:
Choice A. electrons would be required for displacing
of aluminum from a solution of
ions.
Assumption: by " ions" the question meant
with a charge of
on each ion.
Explanation:
The question states that the relative atomic mass of is
. In other words, each mole of
Therefore, that of silver that were formed would contain
of silver atoms.
Metallic silver would precipitate out of this solution only after these ions are turned into
atoms.
One ion carries one unit of positive electrical charge. On the other hand, each
carries one unit of negative electrical charge.
Therefore, each ion will need to gain one electron to form a neutral
atom.
.
At least of electrons would be required to turn
of
ions into that
of silver atoms (which have a mass of
.)
Hence, .
Unlike ions, each aluminum ion
carries three units of positive electrical charge. That is three times the amount of charge on one
ion. Therefore, three electrons will be required to turn one
ion to an
atom.
The question states that the relative atomic mass of is
. Therefore, each mole of
atoms would have a mass
. There would be
of atoms in that
of
.
It takes of electrons to turn one mole of
ions to one mole of
atoms. Hence,
of electrons would be required to produce that
of
atoms (which has a mass of
) from
ions.
That corresponds to the first choice, electrons.