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nevsk [136]
3 years ago
15

What should be the temperature of the solvent before adding it to the sample to be recrystallized?

Chemistry
1 answer:
Serhud [2]3 years ago
3 0

Answer:

Near the boiling point of the solvent

Explanation:

The process of recrystallization is hinged on the fact that the amount of solute that can be dissolved by a solvent increases with temperature. The process involves creation of a solution by dissolving a solute in a solvent at or near its boiling point.  At the boiling point of the solvent, the solute has a greater solubility in the solvent; not much volume of  the hot solvent is required to dissolve the solute.

Before the solution is later cooled, you can now filter out insoluble impurities from the hot solvent. The quantity of the original solute drops appreciably because impurities have been removed. At this lower temperature, the solution becomes saturated and the solute can no longer be held in solution hence it forms pure crystals of solute, which can be recovered.

Recrystallization must be carried out using the proper solvent. The solute must be relatively insoluble in the solvent at room temperature but more soluble in the solvent at elevated temperature.

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Chemistry Help (Naming Oxyacids Chart)
guapka [62]

Answer:

HClO₃ /chloric acid /suffix -ic/ ClO₃⁻ (chlorate)

HClO₂/ chlorous acid/ suffix -ous/ ClO₂⁻ (chlorite)

HNO₃ /nitric acid /suffix -ic/ NO₃⁻ (nitrate)

HNO₂/ nitrous acid/ suffix -ous/ NO₂⁻ (nitrite)

Explanation:

Chlorine has 4 positive oxidation numbers to form oxyacids: +1, +3, +5 and +7.

  • When it uses the oxidation number +5, it forms HClO₃, which is named chloric acid, with the suffix -ic. When it loses an H⁺, it forms the oxyanion ClO₃⁻ (chlorate).
  • When it uses the oxidation number +3, it forms HClO₂, which is named chlorous acid, with the suffix -ous. When it loses an H⁺, it forms the oxyanion ClO₂⁻ (chlorite).

Nitrogen has 2 positive oxidation numbers to form oxyacids: +3 and +5.

  • When it uses the oxidation number +5, it forms HNO₃, which is named nitric acid, with the suffix -ic. When it loses an H⁺, it forms the oxyanion NO₃⁻ (nitrate).
  • When it uses the oxidation number +3, it forms HNO₂, which is named nitrous acid, with the suffix -ous. When it loses an H⁺, it forms the oxyanion NO₂⁻ (nitrite).
7 0
3 years ago
Which statement best describes the relationship between photosynthesis and cellular respiration?
Elena L [17]

Answer:

Photosynthesis removes carbon from the atmosphere, and cellular respiration releases carbon back into the atmosphere.

Explanation:

The first option clearly expresses the relationship between photosynthesis and cellular respiration.

Cellular respiration releases carbon back into the atmosphere whereas photosynthesis removes the carbon from the atmosphere.

Photosynthesis is the process whereby green plants manufacture their food using carbon dioxide and water.

In cellular respiration, the product of the photosynthesis is used by organisms to produce energy.

5 0
3 years ago
The value of the solubility product constant for Ag2CO3 is 8.5 × 10‒12 and that of Ag2CrO4 is 1.1 × 10‒12. From this data, what
Lena [83]

Answer:

B) 7.7

Explanation:

For the reaction    Ag2CO3(s) + CrO42‒(aq) → Ag2CrO4(s) + CO32‒(aq)

Kc = (CO₃²⁻) / (CrO₄²⁻)

and the Ksp given are

Ag₂CO₃    ⇒  2 Ag⁺(aq) + CO₃²⁻(aq)    Ksp₁ = (Ag⁺)²(CO₃²⁻)  

Ag₂CrO₄   ⇒  2 Ag⁺(aq)+ CrO₄²⁻(aq)   Ksp₂ = (Ag⁺)²(CrO₄²⁻)

Where (...) indicate concentrations M

Notice if we divide the expressions for Ksp we get:

Ksp₁/Ksp₂ = (CO₃²⁻)  / (CrO₄²⁻) = 8.5 x 10⁻¹² / 1.1 x 10⁻¹² = 7.7

which is the desired answer.

7 0
3 years ago
PLEASE HELP NEED THIS TO PASS!!!
nadya68 [22]

(1)

At phase A, the water is fully solid, At phase C the water is fully liquid and at phase E the water is fully gas. At this ponts all the substance is in one state other than the fact that its molecules are getting more excited as they gain more energy. This is why there is an increase in temperatures. At the transition points water is changing phase and therefore at any point in between the transition not all water will be in the same phase.

(2)

Point F

This is because the solid water stops rising in temperatures and begins changing phase into liquid water. This is the highest temperatures that the solid water can attain without turning into liquid. You can see from the graph that the temperatures rise at this point levels off between point F and G  

(3)

Point H

This is because the liquid water stops rising in temperatures and begins changing phase into gaseous form. This is the highest temperatures that the liquid water can attain without turning into gas/water vapor. You can see from the graph that the temperatures rise  at this point levels off between point H and I.

(4)

The energy is increasing

You can see from the graph that energy is being absorbed by the water (due to increases in energy on the x-axis on the graph) but there is no corresponding rise in temperatures in y-axis. This means the energy begin absorbed is being used to change the phase of the water.

(5)

The water is changing phases

Because the energy absorbed is being used to change the phase of the liquid. The energy is being used to break the bonds between the molecules so the molecules become farther apart and causing a change in phase on the water. Therefore the vibrational moments of the molecules (responsible for rising in temperatures) remain the same over this latent phase. This energy absorbed to change phase is called latent energy/heat.  

Learn More:

For more on change of phase of water check out;

brainly.com/question/2128466

brainly.com/question/13251064

#LearnWithBrainly

3 0
3 years ago
If a Kleenex box has a length of 8cm, width or 2cm, and a height of 4cm what is the volume of the Kleenex box?
Anettt [7]

Answer:

The volume of the Kleenex box is 64 cm.

Explanation:

Volume = B x W x H

So:      V = 8cm x 2cm x 4cm = 64cm

3 0
3 years ago
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