Question

Suppose 16.0 g of oxygen (O2) is heated at constant atmospheric pressure from 26.4°C to 111°C. (a) How many moles of oxygen are present? (Take the molar mass of oxygen to be 32.0 g/mol) (b) How much energy is transferred to the oxygen as heat? (The molecules rotate but do not oscillate.) (c) What fraction of the heat is used to raise the internal energy of the oxygen?

Answer 1

a)n=0.5 mol

b)n=0.5 mol

c)U/Q=0.714

Step-by-step explanation:

Given that

Mass of oxygen m= 16 g

Heated from 26.4°C to 111°C

Molar weight M=32 g/mol

a)

Number of mole,n

n=m/M

n=16/32 mol

n=0.5 mol

b)

Heat,Q

Q= n Cp ΔT

As we know that it is diatomic gas so

Cp=(7/2)R

Q=7 R n ΔT/2

Now by putting the values

`\Delta U=(7nR\Delta T)/(2)`----1

`Q=(7* 8.314* 0.5* (111-26.4))/(2)`

Q=1230.88 J

We know that internal energy

`\Delta U=(5nR\Delta T)/(2)`--------2

From equation 1 and 2

U/Q= 5/7

U/Q=0.714