How many joules of heat are released when 50 grams of water are cooled from 70C to 60C ?

1 Answer
Mar 28, 2018

#"2000 J"# of heat energy are released.

Explanation:

Use the following formula:

#q=mcDeltaT#,

where:

#q# is heat energy, #m# is mass, #c# is specific heat, and #DeltaT# is change in temperature. #Deltat=T_"final"-T_"initial"#.

Known/Given

#m="50 g"#

#c="4.184 J/(g"*""^@"C")#

#T_"inital"="70"^@"C"#

#T_"final"="60"^@"C"#

#DeltaT=60^@"C"-70^@"C"##=##-10^@"C"#

Unknown

#q#

Solution

Plug in the known/given values and solve.

#q=(50color(red)cancel(color(black)("g")))((4.184 " J")/(color(red)cancel(color(black)("g"))*""^@color(red)cancel(color(black)("C"))))(-10^@color(red)cancel(color(black)("C")))##=##-2000# #"J"# (rounded to one significant figure)

The negative sign means that energy was released.