Question

What is the maximum mass of ethyl alcohol you could boil with 2000 JJ of heat, starting from 17 ∘C∘C?

Answer 1

Answer:

maximum mass C2H5OH = 13.398 g

Explanation:

• Q = mCpΔT

∴ Q = 2000 J

∴ Cp C2H5OH = 112.0 J/mol.K

∴ T1 = 17°C = 290 K

∴ T2 = Tboil C2H5OH = 78.4°C = 351.4 K

⇒ ΔT = 351.4 K - 290 K = 61.4 K

∴ m = Q/CpΔT

⇒ mol C2H5OH = (2000 J)/((112.0 J/mol.K)(61.4 K)) = 0.29083 mol

∴ mm C2H5OH = 46.07 g/mol

⇒ mass C2H5OH = (0.29083 mol)×(46.07 g/mol) = 13.398 g

Answer 2

Answer:                  Q=mcΔT

Explanation:

c ethyl alcohol = 2400 J/(kg*K)

T boil ethyl alcohol = 78 C = 351 K

T starting = 17 C = 290 K

m=Q/(c*ΔT)

m= (2400 J)/[(2400 J/kg*K)(351 K -290 K)]

= 0.0028g