False, a physical change means that the property of matter will change size, shape, color, or density. These are all examples of physical change.
Answer:
B. II.
Explanation:
The idea of recrystallization works when the solubility of the target substance decreases as the temperature of the solution decreases.
The method of recrystallization involves dissolving the solute in a suitable hot solvent and then allow the solution to cool gradually. The pure solute dissolves in the hot solvent and then separates out of the solution as it is cooled to room temperature.
Hence recrystallization is preferred over solvent extraction when the desired compound is poorly soluble in the solvent pair at low temperatures and greatly soluble in the solvent pair at high temperatures.
Answer:
The globs rises due to convection.
Explanation:
Convection is when warmer parts move to the top and the cooler parts move to the bottom. Since the globs are going to be warmer, they rise to the top.
Hope this helps :D
Answer:
ΔH° = + 6.2 kJ
Explanation:
Fe₂O₃(s) + 3CO(g) –––––> 2 Fe(s) + 3 CO₂(g); ΔH° = –26.8 kJ ......... ( 1 )
FeO(s) + CO(g) –––––> Fe(s) + CO₂(g); ΔH° = –16.5 kJ .........( 2 )
Multiplying equation ( 2 ) by 2 and subtracting it from ( 1 )
Fe₂O₃(s) + 3CO(g) -2 FeO(s) - 2CO(g) ––> 2 Fe(s) + 3 CO₂(g) - 2Fe(s) - 2CO₂(g) ΔH° = –26.8 kJ - ( 2 x –16.5 kJ )
Fe₂O₃(s) + CO(g) -2 FeO(s)––> CO₂(g) ΔH° = –26.8 kJ + 33 kJ
Fe₂O₃(s) + CO(g) ––>2 FeO(s) +CO₂(g) ΔH° = + 6.2 kJ
Required ΔH° = + 6.2 kJ Ans .
