Calculate the amount of heat needed to melt 160. g of solid octane (C8H18 ) and bring it to a temperature of 99.2 degrees c. Round your answer to 3 significant digits. Also, be sure your answer contains a unit symbol.

The amount of heat needed to melt the given amount of octane is 84.6 kJ

Explanation:

We know:

Boiling point of Octane =

Few processes involved are:

(1):

(2):

Calculating the heat absorbed for the process having same temperature:

......(i)

where,

q is the amount of heat absorbed, n is the moles of sample and is the enthalpy of fusion

Calculating the heat released for the process having different temperature:

......(ii)

where,

n = moles of sample

= specific heat of liquid

are final and initial temperatures respectively

The number of moles is defined as the ratio of the mass of a substance to its molar mass.

The equation used is:

......(3)

Given mass of octane = 160. g

Molar mass of octane = 114.23 g/mol

Plugging values in equation 3:

We are given:

Putting values in equation (i), we get:

We are given:

Putting values in equation (ii), we get:

Calculating the total amount of heat released:

Hence, the amount of heat needed to melt the given amount of octane is 84.6 kJ

explanation:

answer: semi-infinite solid initially at a uniform temperature of 400 ◦c is cooled at its surface by convection. the cooling fluid at a constant temperature of 200 ◦c has a convective coefficient (ha) of 250 w/m2.k. the physical properties of the solid: k = 20 w/m.k and α = 4 * 10-5  m2/s. using δx = 0.04 m and δt = 10 s. write the finite difference equations describing the transient heat transfer of the first five δx and the temperature profile after 30 s.