All categories

2 years ago

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

Chemistry

1 answer:

Serhud [2]2 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.

You might be interested in

3. (01.03 MC)

sleet_krkn [62]

The majority of wind turbines consist of three blades mounted to a tower made from tubular steel. There are less common varieties with two blades, or with concrete or steel lattice towers. At 100 feet or more above the ground, the tower allows the turbine to take advantage of faster wind speeds found at higher altitudes.

Turbines catch the wind's energy with their propeller-like blades, which act much like an airplane wing. When the wind blows, a pocket of low-pressure air forms on one side of the blade. The low-pressure air pocket then pulls the blade toward it, causing the rotor to turn. This is called lift. The force of the lift is much stronger than the wind's force against the front side of the blade, which is called drag. The combination of lift and drag causes the rotor to spin like a propeller. So therefore your answer would be A.

If this helped could you leave a brainlyest?

8 0

2 years ago

What is the oxidation number of cl− in the hypochlorite ion clo−?

mariarad [96]

Answer : The oxidation number of chlorine (Cl) is, (+1)

Explanation :

Oxidation number : It represent the number of electrons lost or gained by the atoms of an element in a compound.

Oxidation numbers are generally written with the sign (+) and (-) first and then the magnitude.

When the atoms are present in their elemental state then the oxidation number will be zero.

Rules for Oxidation Numbers :

The oxidation number of a free element is always zero.

The oxidation number of a monatomic ion equals the charge of the ion.

The oxidation number of Hydrogen (H) is +1, but it is -1 in when combined with less electronegative elements.

The oxidation number of oxygen (O) in compounds is usually -2, but it is -1 in peroxides.

The oxidation number of a Group 1 element in a compound is +1.

The oxidation number of a Group 2 element in a compound is +2.

The oxidation number of a Group 17 element in a binary compound is -1.

The sum of the oxidation numbers of all of the atoms in a neutral compound is zero.

The sum of the oxidation numbers in a polyatomic ion is equal to the charge of the ion.

The given compound is, $ClO^-$

Let the oxidation state of 'Cl' be, 'x'

$x+(-2)=-1\\\\x-2=-1\\\\x=+1$

Therefore, the oxidation number of chlorine (Cl) is, (+1)

5 0

3 years ago

Nistu is cooking rice in a pot. When she leaves the pot on the stove for a while, the temperature of the rice increases. What ha

Mila [183]

Answer:

Their average kinetic energy increases

Explanation:

The average kinetic energy of the rice molecules increases as the pot is left on the cooking stove.

Heat is transferred to the pot by conduction from the heat source. The heat is then transferred to the rice in the cooking pot by convection.

As the water in the pot heats up.
The rice gains thermal energy.
This causes the molecules of the rice particles to start vibrating.
As the molecules vibrate about their fixed position, their thermal energy continues to increase.
Therefore, the amount of heat absorbed by the rice increases with time and this actually cooks the food.

5 0

3 years ago

Read 2 more answers

Which of the following is not true about sedimentary rocks?

Klio2033 [76]

Answer: [D]: "They are not part of the rock cycle." .
______________________________________________________

6 0

3 years ago

Read 2 more answers

Electrolytes are defined as those compounds which: have covalent bonding produce less lowering at the freezing point than do com

Fofino [41]

Answer:

Electrolytes are defined as those compounds which dissolve in a solvent such as water to produce a solution which conducts electric current easily.

Explanation:

Electrolytes are chemical compounds that dissolve in a solvent such as water and dissociate into ions (cations and anions) which helps to conduct electric current. They can be solids, liquids, or solutions and examples include all ionic compounds such as sodium chloride, calcium chloride, etc.

When electrodes are placed in a solution containing an electrolyte, the ions produced in the solution move from one electrode to the other. The negatively charged ions called anions are attracted to the positive electrode and the positively charged ions called cations are attracted to the negative electrode. This movement of ions generates an electric current. Electrolytes are also needed for the various electrochemical processes in living things and the main ions in these electrolytes are sodium (Na+), calcium (Ca2+), potassium (K+), magnesium (Mg2+), chloride (Cl-), etc.

4 0

3 years ago

Read 2 more answers