Question

Which will have the smallest temperature change for a given addition of energy?

Select one:

a. 10.00 g gold (c = 25.4 J/mol • °C)

b. 10.00 g water (c = 75.3 J/mol • °C)

c. 5.00 g gold (c = 25.4 J/mol • °C)

d. 5.00 g water (c = 75.3 J/mol • °C)

Answer 1

We know that heat energy , Q = mcdt

Where

m = mass

c = specific heat capacity

dt = change in temperature

For the given compounds product of m & c are as follows:

a. 10.00 g gold (c = 25.4 J/mol • °C= 25.4J/(197 g ^oC) = 0.13 J/g^oC) ----> 10.00x0.13 = 1.3 J/^oC

b. 10.00 g water (c = 75.3 J/mol • °C= 75.3 J/(18 g ^oC) = 4.18 J/g^oC) ----> 10.00x4.18 = 41.8 J/^oC

c. 5.00 g gold (c = 25.4 J/mol • °C= 25.4J/(197 g ^oC) = 0.13 J/g^oC) ----> 5.00x0.13 = 0.65 J/^oC

d. 5.00 g water (c = 75.3 J/mol • °C= 75.3 J/(18 g ^oC) = 4.18 J/g^oC) ----> 5.00x4.18 = 20.9 J/^oC

For a given addition of energy smallest temperature change will occur for (b) 10.00 g water (c = 75.3 J/mol.°C) since it has highest value 41.8 J/^oC

Therefore option (b) is correct.