<span>The student should
follow following steps to make 1 L of </span>2.0 M CaCl₂.<span>
<span>
1. First he should
calculate the number of moles of 2.0 M CaCl</span></span>₂ in 1 L solution.<span>
</span>Molarity of the solution = 2.0 M<span>
Volume of solution which should be prepared = 1 L
Molarity =
number of moles / volume of the solution
Hence, number of moles in 1 L = 2 mol
2. Find
out the mass of dry CaCl</span>₂ in 2 moles.<span>
moles =
mass / molar mass
Moles of CaCl₂ =
2 mol</span><span>
Molar mass of CaCl₂ = </span><span>110.98 g/mol
Hence, mass of CaCl</span>₂ = 2 mol x <span>110.98 g/mol
= 221.96
g
3. Weigh the mass
accurately
4. Then take a cleaned and dry1 L volumetric flask and place a funnel top of it. Then carefully add the salt into the volumetric flask and
finally wash the funnel and watch glass
with de-ionized water. That water also should be added into the volumetric
flask.
5. Then add some
de-ionized water into
the volumetric flask and swirl well until all salt are
dissolved.
<span>6. Then top up to
mark of the volumetric flask carefully.
</span></span>
7. As the final step prepared solution should be labelled.
We need the reading for this I think
Answer:
B: Adding water, then adding solute
Explanation:
This is because, say you have a solution with a certain concentration.
If you add more water, it will become more diluted (less concentrated)
If you add more solute, it will become more concentrated.
Therefore if you add water and solute, it could cancel out, and the concentration would remain the same.
Hope this helps! Let me know if you have any questions/ would like anything further explained :)
The number of oxygen atoms is in 5.00 g of sample of sodium dichromate, Na₂Cr₂O₇ is 1.125 x 10²³ atoms.
<h3>What is sodium dichromate?</h3>
Sodium dichromate is an inorganic compound. It is sued in tanning and mental illness.
The molar mass of sodium = 23 gm
The molar mass of Cr = 51.99 gm
The molar mass of oxygen = 16 gm
Molar mass of Na₂Cr₂O₇ = 2(23) + 2(51.99) + 7(16) = 261.98 gm
Number of moles in 7 gm = mass / molar mass = 7 / 261.98 = 0.0267 moles
1 mole of Na₂Cr₂O₇ contains 7 moles of oxygen, therefore:
The number of moles of oxygen in 0.0267 moles = 0.0267 x 7 = 0.1869 moles
Thus, the number of atoms = 0.1869 x 6.02 x 10^23 = 1.125 x 10²³ atoms.
To learn more about sodium dichromate, refer to the link:
brainly.com/question/1444529
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