Energy is required to change the phase of a substance, such as the energy to break the bonds between molecules in a block of ice so it may melt.
During a phase change energy my be added or subtracted from a system, but the temperature will not change. The temperature will change only when the phase change has completed. No temperature change occurs from heat transfer if ice melts and becomes liquid water (i.e., during a phase change). For example, consider water dripping from icicles melting on a roof warmed by the Sun. Conversely, water freezes in an ice tray cooled by lower-temperature surroundings. Energy is required to melt a solid because the cohesive bonds between the molecules in the solid must be broken apart so that the molecules can move around at comparable kinetic energies; thus, there is no rise in temperature.
Answer:
(C) The recrystallization solvent should be nonvolatile.
Explanation:
Recrystallization is the separation technique which is used to purify the solid compounds in their crystal or amorphous form.
Some properties follow the recrystallization process as:
The solids are more soluble in hot solvent as compared to the solubility in the cold solvent.
The solvent must have lower boiling point and can be volatile easily.
The solvent should not react with the compound.
The impurities must be soluble in the cool solvent, so that only the pure product crystallizes.
Hence, Answer - C which is not an ideal characteristic.
Answer:
your answer will be b) bonds are breaking
Answer:
A. True
Explanation:
The octane number is determined by comparing the characteristics of gasoline to isooctane (2,2,4-trimethylpentane) and heptane. The correct option is option A.
Basically, the higher the octane number, the greater the resistance of the gasoline to knocking.
