Question

When 50.0 mL of 1.0 mol/L hydrochloric acid is neutralized completely by 75.0 mL of 1.0 mol/L sodiumhydroxide in a coffee-cup calorimeter, the temperature of the total solution changes from 20.2℃to25.6℃. Determine the quantity of energy transferred, q, and state whether the reaction wasendothermic or exothermic

Answer 1

In this question, we have a neutralization reaction occurring and giving a value of heat, the informations we have are:

HCl = 50.0 mL and 1.0 M

NaOH = 75.0 mL and 1.0 M

ΔT = 20.2 - 25.6 = -5.4°C

We will be using the calorimetry formula in this situation, adding the values of the quantity of both reactants and using the specific heat capacity of water, c = 4.19J, the formula is:

Q = mcΔT

We have:

m = 50+75

c = 4.19J

ΔT = - 5.4

Now we add these values into the formula:

Q = 125 * 4.19 * - 5.4

Q = -2.83 kJ, this is the overall enthalpy, or energy transferred, and the minus sign in front of the number indicates that this is an exothermic reaction.