Question #f51b9

1 Answer
Jul 20, 2017

Answer:

#"530 J"#

Explanation:

In order to be able to answer this question, you need to know the specific heat of silver.

#c_"Ag" = "0.240 J g"^(-1)""^@"C"^(-1)#

http://www2.ucdsb.on.ca/tiss/stretton/database/specific_heat_capacity_table.html

Now, the specific heat of silver tells you the amount of energy needed to increase the temperature of #"1 g"# of silver by #1^@"C"#.

You can thus say that if you add #"0.240 J"# of heat to #"1 g"# of silver, its temperature will increase by #1^@"C"#.

In your case, the temperature of the sample must increase by

#78^@"C" - 15^@"C" = 63^@"C"#

so use the specific heat to calculate the amount of heat needed to increase the temperature of a sample of silver by #63^@"C"#.

#63 color(red)(cancel(color(black)(""^@"C"))) * "0.240 J"/("1 g" * 1 color(red)(cancel(color(black)(""^@"C")))) = "15.12 J g"^(-1)#

This tells you that in order to increase the temperature of silver by #63^@"C"#, you must add #"15.12 J:"# of heat for every #"1 g"# of silver.

You can thus say that your sample will require

#35 color(red)(cancel(color(black)("g"))) * overbrace("15.12 J"/(1color(red)(cancel(color(black)("g")))))^(color(blue)("for a 63"""^@"C increase in temperature")) = color(darkgreen)(ul(color(black)("530 J")))#

The answer is rounded to two sig figs, the number of sig figs you have for your values.