Answer:
Two characteristics that make water a good choice for the recrystallization solvent for benzoic acid are
- Low solubility for benzoic acid at room temperature
- Less expensive
Explanation:
Characteristics of a Good Recrystallization Solvent:
- Cheap.
- High volatility.
- No reaction with substrate to be made pure.
- Insoluble impurities should not be dissolced by the olvent at all temperatures.
- At room temperature the solvent should have high solubility for soluble impurities well
- At room temperature the substance to be purified should be insoluble in the solvent.
As such water has both low solubility for benzoic acid at room temperature and water is cheap or readily available
Answer:
True
Explanation:
Friction is defined as the force that opposes motion when an object is sliding over a surface.
As a result of friction, all objects moving over a surface eventually come to rest over time.If we were to successfully create a friction-less surface, an object will remain in motion forever because it will encounter no opposition to its motion.
Hence, the resistance to the motion of objects over a surface which causes the objects to come to a halt after moving over the surface for some time is called friction.
<u>Answer:</u> This violates the law of constant composition.
<u>Explanation:</u>
Dalton's theory is based on mainly two laws, which are law of conservation of mass and law of constant composition.
Law of constant composition states that a compound always contain the elements in the fixed ratio by their masses.
For Example: In water 
, the hydrogen and oxygen are present in the fixed ratio of 1 : 9 by their mass.
We are given:
A sample of titanium dioxide having 59.95 % of titanium and another sample of titanium dioxide having 60.10 % of titanium.
As, the compound is titanium dioxide. So, the mass percent of titanium must remain the same in both the elements.
Hence, this violates the law of constant composition.
Answer:
1) Dispersion forces: It is a type of force which is present between atoms and molecules. It is a weakest intermolecular force that occurs between atoms. It is also called induced dipole-induced dipole attraction.
2. Dipole-dipole: It is a type of attractive force which is present between the negative end of one molecule with the positive end of another molecule. This type of attractive force occurs between polar molecules.
3) Hydrogen bond: It is a type of electromagnetic force which is present between hydrogen and high electronegative atoms such as nitrogen and oxygen etc.
Answer:
If the moles of gas are tripled, the volume must also triple.
Explanation:
According to Avogadro law,
Equal volume of all the gases at same temperature and pressure have equal number of molecules.
The number of moles and volume are directly related to each other. By increasing the number of moles volume also goes to increase with same ratio.
When number of moles decreases the volume also goes to decrease at constant temperature and pressure.
Mathematical expression:
V ∝ n
V = Kn
V/n = k
When volume is changed from V₁ to V₂ by changing the number of moles from n₁ to n₂. Then expression will be,
V₁/n₁ = V₂/n₂
