Question f51b9

1 Answer
Jul 20, 2017

$\text{530 J}$

Explanation:

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

${c}_{\text{Ag" = "0.240 J g"^(-1)""^@"C}}^{- 1}$

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 $\text{1 g}$ of silver by ${1}^{\circ} \text{C}$.

You can thus say that if you add $\text{0.240 J}$ of heat to $\text{1 g}$ of silver, its temperature will increase by ${1}^{\circ} \text{C}$.

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

${78}^{\circ} \text{C" - 15^@"C" = 63^@"C}$

so use the specific heat to calculate the amount of heat needed to increase the temperature of a sample of silver by ${63}^{\circ} \text{C}$.

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 ${63}^{\circ} \text{C}$, you must add $\text{15.12 J:}$ of heat for every $\text{1 g}$ of silver.

You can thus say that your sample will require

$35 \textcolor{red}{\cancel{\textcolor{b l a c k}{\text{g"))) * overbrace("15.12 J"/(1color(red)(cancel(color(black)("g")))))^(color(blue)("for a 63"""^@"C increase in temperature")) = color(darkgreen)(ul(color(black)("530 J}}}}$

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