Question

The mass of water is 70.0 g. What is the energy required to heat a beaker of water at 18 degrees C to boiling?

Answer 1

The energy required is 24 kJ.

Explanation:

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

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

where

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

In your problem,

`m = "70.0 g"`
`c = "4.179 J"·"°C"^"-1"·"g"^"-1"`
`ΔT = "(100 - 18) °C" = "82 °C"`

∴ `q = 70.0 color(red)(cancel(color(black)("g"))) × "4.179 J"·color(red)(cancel(color(black)("°C"^"-1"·"g"^"-1"))) × 82 color(red)(cancel(color(black)("°C"))) = "24 000 J" = "24 kJ"`