Question

Liquid sodium is being considered as an engine coolant. How many grams of liquid sodium (minimum) are needed to absorb 8.10 MJ of energy in the form of heat if the temperature of the sodium is not to increase by more than 10.0 °C? Use C P = 30.8 J / ( K ⋅ mol ) for Na ( l ) at 500 K .

Answer 1

Answer: 21374 g of liquid sodium are needed to absorb 8.10 MJ of energy.

Step-by-step explanation:

The quantity of heat required to raise the temperature of a substance by one degree Celsius is called the specific heat capacity.

`Q=m* c* \Delta T`

Q = Heat absorbed=
`8.10MJ=8.10* 10^6J`
`(1MJ=10^6J`

m= mass of substance = ?

c = specific heat capacity = 30.8J/Kmol

Change in temperature ,
`\Delta T=T_f-T_i=10^0C=(10+273)K=283K`

Putting in the values, we get:

`8.10* 10^6J=m* 30.8J/Kmol* 283K`

m= 929 mol

Mass of sodium =
`moles* {\text {Molar mass}}=929mol* 23g/mol=21374g`

Thus 21374 g of liquid sodium are needed to absorb 8.10 MJ of energy.