Question #0b2c1
1 Answer
Explanation:
In order to be able to answer this question, you must know the value of the specific heat of water, which you'll find listed as
c_"water" = "4.18 J g"^(-1)""^@"C"^(-1)cwater=4.18 J g−1∘C−1
The specific heat of a substance tells you the amount of heat needed in order to increase the temperature of
In this case, you need
You know that the temperature of the water must change by
DeltaT = 65^@"C" - 10^@"C" = 55^@"C"
so start by calculating the amount of heat needed to increase the temperature of
55color(red)(cancel(color(black)(""^@"C"))) * "4.18 J"/("1 g" * 1color(red)(cancel(color(black)(""^@"C")))) = "229.9 J g"^(-1)
Your sample has a mass of
0.5 color(red)(cancel(color(black)("kg"))) * (10^3"g")/(1color(red)(cancel(color(black)("kg")))) = "500 g"
which means that the amount of heat needed to increase its temperature by
500color(red)(cancel(color(black)("g"))) * "229.9 J"/(1color(red)(cancel(color(black)("g")))) = "114950 J"
I'll leave the answer rounded to two sig figs and expressed in kilojoules, but do keep in mind that you only have one significant figure for the mass of the sample
color(darkgreen)(ul(color(black)("heat needed = 1.1 kJ")))
