1 When 25 cm of 1.0 mol/dmº copper sulfate solution was mixed vith an excess of zinc powder, the temperature of the solution rose by 50.6 °C. Calculate the energy change
for the reaction in kJ/mol.
CuSO4(aq) + Zn(s) + Cu(s) + ZnSO4(aq)
?

See explanation

Explanation:

From the formula for heat;

q (enthalpy change) = (mass of solution) x (specific heat capacity) x (temperature change)

Since the density and heat capacity of the solution are the same as that of pure water.

Mass of copper sulphate solution = 50 g

Heat = 50 * 4.18 * 50.6°C

Heat = 10575.4 J

Number of moles = 1 * 25/1000 = 0.025 moles

10575.4 J/ 0.025 moles = 432016 J/mol/1000

= 423 KJ/mol

or

q = - 423 KJ/mol

given:

mass of na = 115 g

excess cl2

to determine:

mass of nacl produced

explanation:

given reaction is-

2na(s) + cl2(g) → 2nacl(s)

since cl2 is in excess, na will be the limiting reagent

as per the reaction stoichiometry na: nacl = 1: 1

i.e. moles of na reacted = moles of nacl formed

now, # moles of na = mass of na/atomic mass

                                  = 115 g/23 g.mol-1 = 5 moles

therefore, moles of nacl = 5

molar mass of nacl = 58 g/mol

mass of nacl = 5 moles * 58 g.mol-1 = 290 g

ans: amount of nacl produced = 290 g