Question

Calculations Sheet Thermochemistry 2 Part 2: Hydrochloric Acid + Magnesium The strategy for these calculations are similar to those in Part I. In Part 2, magnes reagent. Volume of hydrochloric acid solution 75.0 mL Part 1. In Part 2, magnesium is the limiting Density of hydrochloric acid solution 102 g ml." dem Mass of hydrochloric acid solution (d-m/V) Specific heat capacity of hydrochloric acid solution 4.68 9.84 °C C Change in temperature for reaction AH(-MSAT) Mass of magnesium mol Moles of magnesium J. mol AH per mole of Mgo moles Mg _kJ mol' AH per 1 mole Mg (1 kJ = 1000) * Use the mass and atomic mass of Mg **The amount of heat we measured is, according to the equation below, per 1 mol of Mg. Mg(s) + 2HCl(aq) → MgCl2(aq) + H, (g)

Answer 1

From the given data,

Volume of hydrochloric acid solution is 75 mL

Density of hydrochloric acid solution is 1.02 g.mL^-1

Mass of hydrochloric acid solution is (d = m/V) 76.5 grams

From the given formula density (d) = Mass / Volume

We have density of HCl - 1.02 g/mL and Volume of HCl - 75 mL

Therefore, 1.02 g/mL = Mass / 75 mL

Mass = 75 x 1.02 g = 76.5 grams

Specific heat capacity of hydrochloric acid solution is 4.68 J.g^-1.^oC^-1

Change in temperature for the reaction is 7.84 ^oC

$\Delta$H = (-mS$\Delta$T) = -2806.88 Joules

'm' is the mass of HCl = 76.5 grams

'S' is the specific heat capacity of HCl = 4.68 J.g^-1.^oC^-1

$\Delta$T is change in temperature = 7.84 ^oC

Therefore $\Delta$H = (-mS$\Delta$T) = - 76.5 grams x 4.68 J.g^-1.^oC^-1 x 7.84 ^oC = -2806.88 Joules