Answer:
E. Water Freezing
Explanation:
Entropy refers to the degree of disorderliness of a system.
A. Water Evaporating: There is an increase in entropy, this is because the phase change is from liquid to gas. Gas particles are more disordered than liquid.
B. Dry Ice sublimating: Sublimating refers to a phase change from solid to gas. This is an increase in entropy, this is because the gas particles are more disordered than solid particles
C. Water Boiling: The phase change is from liquid to gaseous state. There is an increase in entropy. Gas particles are more disordered than liquid.
D. Ice melting: The phase change is from solid to liquid state. There is an increase in entropy. Liquid particles are more disordered than that of solid.
E. Water Freezing: The phase change is from liquid to solid state. There is a decrease in entropy. solid particles are less disordered than those of liquid.
Answer:
Mole fraction for solute = 0.1, or 10%
Molality = 6.24 mol/kg
Explanation:
22.3% by mass → In 100 g of solution, we have 22.3 g of HCOOH
Mass of solution = 100 g
Mass of solute = 22.3 g
Mass of solvent = 100 g - 22.3g = 77.7 g
Let's convert the mass to moles
22.3 g . 1mol/ 46 g = 0.485 moles
77.7 g. 1mol / 18 g = 4.32 moles
Total moles = 4.32 moles + 0.485 moles = 4.805 moles
Xm for solute = 0.485 / 4.805 = 0.100 → 10%
Molality → mol/ kg → we convert the mass of solvent to kg
77.7 g. 1 kg / 1000g = 0.0777 kg
0.485 mol / 0.0777 kg = 6.24 m
Radioactive material obeys 1st order decay kinetics,
For 1st order reaction, we have
k =
where, k = rate constant of reaction
Given: Initial conc. 100, Final conc. = 6.25, t = 18.9 hours
∴ k =
= 0.1467 hours^(-1)
Now, for 1st order reactions: half life =
= 4.723 hours.
