Chemistry thermodynamics

Question

During a neutralisation reaction between acid rain and limestone, 55g of the acid rain began at room temperature (22 degrees C). By the end of the reaction, the acid is 9 degrees C. How much energy is required to cause the temperature change of the acid rain if it’s specific heat is 4.18 J/g degrees Celsius?

Answer 1

First I assign variables to the values given in the problem statement:

mass: m = 55 g

specific heat: c = 4.18 J/g*deg C

change in temperature: delta T = 22-9 = 13 deg C

Then I determine the variable being asked to solve for:

"How much energy" means I am solving for heat, which is the variable "q"

Then I pick an equation that uses all those variables:

q = m*c*(delta T)

Finally I plug in and solve:

q = 55*4.18*13 = 2988.7 (round to 3.0 x 10^3 for significant figures) J