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wel
3 years ago
9

Which of the following solvent pairs could be used in a solvent pair recrystallization (in general, not for this specific reacti

on)? For those selected, briefly explain why. For those not selected, briefly explain why not.
(a) Ethyl acetate and hexane
(b) Water and diethyl ether
(c) Methanol and methylene chloride
Chemistry
1 answer:
lilavasa [31]3 years ago
3 0

Answer:

(a) Ethyl acetate and hexane, and (c) methanol and methylene chloride.

Explanation:

re-crystallization is a technique used to purify solid compound.   Ethyl acetate and hexane are good solvent pair for recrystallization because they are miscible with each other due to their good differences in polarity. ethyl acetate has polarity of 77 while hexane has 68.

water and diethyl ether are not good solvent pair for recrystallization because water and diethyl ether are immiscible. They have very far polarity values. water has 100 while diethyl ether has 35

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3.95 g of sugar (C6H12O6) is dissolved in water to make 158 mL of solution. Find the molarity.
12345 [234]

Answer:

[C₆H₁₂O₆] = 0.139 M

Explanation:

Molarity si defined as a sort of concentration. It indicates the moles of solute that are contained in 1 L of solution.

We can also say, that molarity are the mmoles of solute contained in 1 mL of solution.

For this case, the solute is sugar (glucose). Let's determine M (mmol/mL)

(3.95 g . 1mol / 180g) . (1000 mmol / 1mol) / 158 mL

We determine moles, we convert them to mmoles, we divide by mL

M = 0.139 M

Moles = 3.95 g . 1mol / 180g → 0.0219 mol

We convert mL to L → 158 mL . 1L/1000mL = 0.158L

M = 0.0219 mol / 0.158L = 0.139 M

8 0
3 years ago
Which gas below has the largest number of moles at STP?
ArbitrLikvidat [17]

Answer:

a.) 22.4 L Ne.

Explanation:

It is known that every 1.0 mol of any gas occupies 22.4 L.

For the options:

  • 22.4 L Ne:

<em>It represents </em><em>1.0 mol of Ne.</em>

<em />

  • 20 L Ar:

using cross multiplication:

1.0 mol occupies → 22.4 L.

??? mol occupies → 20 L.

The no. of moles of (20 L) Ar = (1.0 mol)(20 L)/(22.4 L) = 0.8929 mol.

  • 2.24 L Xe:

using cross multiplication:

1.0 mol occupies → 22.4 L.

??? mol occupies → 2.24 L.

<em>The no. of moles of (2.24 L) Xe </em>= (1.0 mol)(2.24 L)/(22.4 L) = <em>0.1 mol.</em>

  • So, the gas that has the largest number of moles at STP is: a.) 22.4 L Ne.

6 0
3 years ago
Definition of steepest
andrey2020 [161]
<span>Hi, friend.
Steepest - Being steep to the greatest degree.
Steep - S</span>harply angled.
Example: When hiking trails lead straight up mountainsides, they've got a steep incline.
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5 0
3 years ago
Read 2 more answers
When can a compound be treated like an element when balancing chemical equations?
Marrrta [24]
A compound can be treated like an element when balancing chemical equations when : A. when there is no change to the atoms in the compound

If they remain together during the reaction, you can treat a compound as a singe atom.

hope this helps
7 0
3 years ago
Read 2 more answers
Find the potentials of the following electrochemical cell:
melomori [17]

Answer: 0.18 V

Explanation:-

Cd/Cd^{2+}(0.10M)//Ni^{2+}(0.50M)?Ni

Here Cd undergoes oxidation by loss of electrons, thus act as anode. nickel undergoes reduction by gain of electrons and thus act as cathode.

E^0_(Cd^{2+}/Cd)=-0.40V[/tex]

E^0_(Ni^{2+}/Ni)=-0.24V[/tex]

Cd+Ni^{2+}\rightarrow Cd^{2+}+Ni

Here Cd undergoes oxidation by loss of electrons, thus act as anode. nickel undergoes reduction by gain of electrons and thus act as cathode.

E^0=E^0_{cathode}- E^0_{anode}

Where both E^0 are standard reduction potentials.

E^0=E^0_{[Ni^{2+}/Ni]}- E^0_{[Cd^{2+}/Cd]}

E^0=-0.24-(-0.40)=0.16V

Using Nernst equation :

E_{cell}=E^o_{cell}-\frac{0.0592}{n}\log \frac{[Cd^{2+}]}{[Ni^{2+]}

where,

n = number of electrons in oxidation-reduction reaction = 2

E^o_{cell} = standard electrode potential = 0.16 V

E_{cell}=0.16-\frac{0.0592}{2}\log \frac{[0.10]}{[0.5]}

E_{cell}=0.18V

Thus the potential of the following electrochemical cell is 0.18 V.

6 0
3 years ago
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