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3 years ago

When doing a recrystallization what observations would prompt

Chemistry

1 answer:

Volgvan3 years ago

5 0

<h2>Observation of purified crystals.</h2>

Explanation:

Recrystallization is the process in which a compound is dissolved in a hot solvent and then allowed to cool which forms the crystals.
It is a technique used for purification of solids.
Recrystallization mainly depends on the solubility of the solvent that means the solid should be soluble in the solvent when it is hot and should be insoluble in the same solvent when it is cool.
The observations while doing recrystallization is to observe the purified crystals obtained and to filter it out.

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3 years ago

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Veseljchak [2.6K]

The concentration in /mmolL of the chemist's silver(I) nitrate solution is 0.01047 mmoles/litre.

Explanation:

Data given:

Number of moles of AgNO3 in micro mole 4.7102micromol.

The concentration is supposed to be in mmol so the micromole will be converted to milimole.

So, 1 micromole = 0.001 millimole

hence, 4.712micromole will be 0.004712 millimole.

Volume is given as 450ml which is converted into L

to convert ml into L it is divided by 1000

so 0.45 L is the volume.

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molarity = $\frac{number of moles}{volume in litres}$

putting the values in the formula:

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4 years ago

A solution is prepared by dissolving 15.0 g of nh3 in 250.0 g of water. the density of the resulting solution is 0.974 g/ml. the

iris [78.8K]

To solve this problem, first we assume the volume is purely additive. The density of the mixture can then be calculated by the summation of mass fraction of each component divided by its individual density:

1 / ρ mixture = (x NH3 / ρ NH3) + (x H2O / ρ<span> H2O) ---> 1</span>

Calculating for mass fraction of NH3:

x NH3 = 15 g / (15 g + 250 g)

x NH3 = 0.0566

Therefore the mass fraction of water is:

x H2O = 1 – x NH3 = 1 – 0.0566

x H2O = 0.9434

Assuming that the density of water is 1 g / mL and substituting the known values back to equation 1:

1 / 0.974 g / mL = [0.0566 / (ρ NH3)] + [0.9434 / (1 g / mL)]

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Given the density of NH3, now we can calculate for the volume of NH3:

V NH3 = 15 g / 0.680 g / mL

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The number of moles NH3 is: (molar mass NH3 is 17.03 g / mol)

n NH3 = 15 g / 17.03 g / mol

n NH3 = 0.881 mol

Therefore the molarity of NH3 in the solution is:

<span>Molarity = 0.881 mol / [(22.07 mL + 250 mL) * (1L / 1000 mL)</span>

8 0

3 years ago

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