Question

Calculate the energy of 1kg of concrete from 20⁰c to 30⁰c​

Answer 1

9 kilojoules of energy are stored in a kilogram of concrete due to sensible heat.

Step-by-step explanation:

In this exercise we need to determined the sensible heat store in a kilogram of concrete due to a change in temperature. Sensible heat (
`Q`), measured in kilojoules, is defined by the following expression:

`Q = m\cdot c\cdot (T_(f)-T_(o))` (1)

Where:

`m` - Mass, measured in kilograms.

`c` - Average specific heat of concrete, measured in kilojoules per kilogram-degree Celsius.

`T_(o)`,
`T_(f)` - Initial and final temperatures of concrete, measured in degrees Celsius.

If we know that
`m = 1\,kg`,
`c = 0.9\,(kJ)/(kg\cdot ^(\circ)C)`,
`T_(o) = 20\,^(\circ)C` and
`T_(f) = 30\,^(\circ)C`, then the energy store in a kilogram of concrete is:

`Q = (1\,kg)\cdot \left(0.9\,(kJ)/(kg\cdot ^(\circ)C) \right)\cdot (30\,^(\circ)C-20\,^(\circ)C)`

`Q = 9\,kJ`

9 kilojoules of energy are stored in a kilogram of concrete due to sensible heat.