What mass of naoh (40.0 g/mol) is needed to prepare 250 ml of 2 m naoh solution?
1 answer:
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Answer:
There are approximately of formula units in that
of
(the solute of this solution.)
Explanation:
A solution includes two substances: the solute and the solvent. Note the solution here contains significantly more water than . Hence, assume that water is the solvent (as it is in many other solutions.)
The (molar) formula mass of is necessary for finding the number of moles of
- One
atom,
- One
atom, and
- One
atom.
The formula mass of will thus be the sum of:
- The mass of one mole of
- The mass of one mole of
- The mass of one mole of
atoms.
On the other hand, the mass (in grams) of one mole of atoms of an element is (numerically) the same as its relative atomic mass. The relative atomic mass data can be found on most modern periodic tables.
Relative atomic mass data from a modern periodic table:
.
.
.
For example, the relative atomic mass of (potassium, atomic number
) is
(3 sig. fig.) Hence, the mass of one mole of
The formula mass of is the sum of these three masses:
.
The number of moles of formula units in this
sample would be:
.
