Question

How much heat does it take to raise the temperature of 2.5 kg of plastic from 15°C to 75°C?

The specific heat of plastic is 2.60 kJ/(kg•°C)

Answer 1

It will take 390 kJ of heat.

Explanation:

The energy `q` required to heat an object is given by the formula

`color(blue)(bar(ul(|color(white)(a/a)q = mcΔTcolor(white)(a/a)|)))" "`

where

`m` is the mass
`c` is the specific heat capacity
`ΔT` is the change in temperature

In your problem,

`m = "2.5 kg"`
`c = "2.60 kJ·°C"^"-1""kg"^"-1"`
`ΔT = T_"f" - T_"i" = "75 °C - 15 °C = 60 °C"`

∴ `q = "2.5" color(red)(cancel(color(black)("kg"))) × "2.60 kJ"·color(red)(cancel(color(black)("°C"^"-1"·"kg"^"-1"))) × "60" color(red)(cancel(color(black)("°C"))) = "390 kJ"`