1. Physical
2. Chemical
3. Physical
4. Physical
5. Chemical
6. I really don't feel like doing 6, sorry.
7. False: energy to mass
11. False: change to exothermic
12. False: change to endothermic
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.
Answer:
Glow sticks and match would be light emission, slime would be preciptate, and cookies would be gas.
Explanation:
Answer:
Salt.
Explanation:
Salt=NaCl
Ionic bonds are made when the two elements are from different sides of the periodic table. On the left, we have our metals. On the right, we have our nonmetals. Sodium is a metal and Chlorine is a gas. Water, sugar, and carbon dioxide are covalent bonds because all the elements are from the right side of the periodic table. Hydrogen is a nonmetal too.
