If you have 600 kJ of heat to spend, and you use it to melt lead, how many ¼ ounce wheel weights (at 20 oC)can you melt?

Question

If you have 600 kJ of heat to spend, and you use it to melt lead, how many ¼ ounce wheel weights (at 20

oC)can you melt? Note that Lead is NOT measured in troy ounces, but proper ones (16 ounces in a pound), the the specific heat of lead is 0.13 J/goC and its melting point is 327.5oC.

Answer 1

Hi, Kiranpreet,

The formula that relates heat and temperature for a material is

q=mcDT

where q is the energy, m is the mass, c is the specific heat, and DT is the temperature change;

We have:

q = 400,000 Joules

m = The unknown

c = 0.13 J/gC

and DT is the temperature change.

400,000J = (0.13 J/gC)*m*(307.5)

m = 15009 grams

1 oz = 28.35g

1500g grams/28.35g/oz = 529.4 oz

We can make 4x529.4 = 2118 1/4 oz wheels.

Bob