A team of university students test a new car they are designing. They find out that 8, 500J of the energy is transferred to movement (kinetic) energy and 3, 500J is transferred as heat energy. They put in a total of 12, 000J of energy in the form of energy from the electric battery. How efficient is this?

1.
дано
m(CH3CL)=2 g
V(прак C2H6)=355.2 ml = 0.3552 L

η-?
    2g                       X L
2CH3CL+2Na-->C2H6+2NaCL  M(CH3CL)=50.5 g/mol , Vm=22.4 L/mol
50.5                     22.4
X=2*22.4 / 50.5 = 0.887 L
η = V(практ) / V(теор)*100% = 0.3552 / 0.887 * 100% = 40 %
ответ 40%

2. дано

М(CH4)=11.2 L
η = 60%

m(CBr4)-?

CH4+4Br2-->CBr4+4HBr
n(CH4)=V / Vm = 11.2 / 22.4 = 0.5 mol
n(CH4)=n(CBr4)= 0.5 mol
M(CBr4)= 332 g / mol
m(CBr4)= n*M = 0.5*332 = 166 g - масса теорит
m(CBr4)=166 * 60% / 100% = 99.6 g - масса практич
ответ 99.6 г