Answer:
The correct answer is:
<em>(1) It is important that the sample is dissolved in just enough hot solvent. </em>
Explanation:
The process of recrystallization is important to eliminate the impurities and to obtain better crystals of the solid. The solvent used to perform the recrystallization must have a high dissolution power of the substance to be recrystallized and a low dissolution power of the impurities. This is in order to eliminate most impurities. Furthermore, <em>It is important that the sample is dissolved in just enough hot solvent </em>because this should be easy to remove after the recrystallization and the crystal should form easily when the solution cools. Also, it is better to add the hot solvent to solubilize the crystals and keep the impurities insoluble, instead of adding the cold solvent and heating the solution. Additionally, the process of cooling the solution must be done slowly to obtain large and fewer crystals. A fast ice-cooling will form smaller crystals.
In general, bonds with an electronegativity difference of 0-0.5 are nonpolar covalent, bonds with an EN difference of 0.5-2.0 are covalent, and anything above 2.0 is considered ionic.
To determine the bond types of the pairs of elements, we will need their EN values. We can subtract their EN values to find their EN difference.
H and Br: 2.96-2.20=0.76
Therefore a bond between H and Br would be moderately polar covalent.
Cl and F: 3.98-3.16=0.82
Therefore this bond is moderately polar covalent.
K and Cl: 3.16-0.82=2.34
Therefore this bond is ionic.
Li and O: 3.44-0.98=2.46
Therefore this bond is ionic.
Br and Br: Because these are the same element, meaning that they have the same EN value, we automatically know that their EN difference would be zero. Therefore, this bond is very covalent.
Answer:
The general electronic configuration of the element present in the 13th group of the periodic table is . Therefore, the number of valence electrons of the group 13this 3. Also, the metalloid element which is present in group 13th is boron. Hence the metalloid which has 3 valance electrons is boron.
Explanation:
Answer:
Dalton's atomic theory was the first complete attempt to describe all matter in terms of atoms and their properties. Dalton based his theory on the law of conservation of mass and the law of constant composition. ... Parts of the theory had to be modified based on the existence of subatomic particles and isotopes.
Explanation:
If the solution is BASIC than it will turn purple but if ACIDIC it will turn pink.