Question

Calculations and Results Part A: Specific Heat Capacity of a Metal (Assume =41841/ Mass of water 39.7g 67.5°C 5.3°C Temperature change of the metal Temperature change of the water Heat transferred to the water Heat transferred to the metal Specific heat capacity of the metal Approximate molar mass of metal (Eqn 5) Identity of the metal Part B: Heat of Reaction for Dissolving a Salt in Water (Assume = 4.002/ Mass of water Mass of solid Mass of solution Temperature change of the solution Heat of solution (que) Heat of the reaction (AHAD) Moles of solid used in the reaction Heat of reaction per mole of solid (I/mol)

please help with filling out tables for Parts A and B

my data is all laid out

on the bottom page

equation 5 is

NaOH(s)---->Na+(aq) + OH-(aq)

Answer 1

Part A: To determine the specific heat capacity of a metal
The metal piece of known mass(given: 37.3 g) is transferred from boiling water to a calorimeter containing water at 27.2°C. As heat is transferred from the metal to water, the final temperature attained is 32.5°C.
The quantity of heat lost by the metal = The quantity of heat lost by the water
$-(\Delta \, Q)\, _{metal}\, =\, (\Delta\, Q )_{water}$
Data for metal:
mass of metal = 37.3 g
ti (metal) = 100.0 °C
tf (metal) = 32.5 °C
$\Delta$ t = 27.2 °C - 100 °C = - 67.5 °C
Data for water:
mass of water = 46.6 g - 6.9 g = 39.7 g
ti (water) = 27.2 °C
tf (water) = 32.5 °C
$\Delta$ t = 32.5 °C - 27.2 °C = 5.3 °C
Specific heat of water = 4.184 J/g°C
Heat transferred to the water Q = m $\times$ C $\times$ $\Delta$t = 39.7 g $\times$ 4.184 J/g°C $\times$ 5.3 °C = 880.35544 J
Heat transferred from the metal = - ( 37.3 g $\times$ C $\times$ -67.5°C ) = 880.35544 J
Hence specific heat of the metal = 880.35544 J/(37.3 g $\times$ 67.5 °C) = 0.3496 J/g °C
Hence specific heat of the metal in calories = 0.3496 /4.184 = 0.08355 cal/g °C
By Dulong and Petit's law:
Approximate atomic mass $\times$ specific heat of the metal in cal/ g°C = 6.4
Approximate atomic mass of the metal= 76.6 u
The specific heat of Cu is 0.385 J/g°C and that of Zn is 0.389 J/g°C
The given metal could be Cu or Zn, however the difference in the values may be duue to experimental error.
Part B: To determine the heat of reaction for dissolving salt in water
Mass of water = 55.7 g - 7.2 g = 48.5 g
Mass of solid = 8.1 g -3.1 g = 5.0 g
Mass of solution = 53.5 g
$\Delta$ t (solution) = tf -ti = 15.4 °C - 22.5°C = - 7.1 °C
Heat of solution you need to know the sheat capacity solution = mass $\times$ C $\times$ $\Delta$t = 53.3g $\times$ 4.002 J/g°C $\times$ - 7.1 °C = -1514.47 6 J = - 1.5 kJ
the -ve sign indicates that the process is endothermic.
Moles od solute (NH4Cl) = 5/53.49 = 0.0935 mol/g
Heat of reaction per mole = - 1.5/0.0935 = - 16.04 J/mol
NOTE: Enthalpy of reaction is taken as positive for an endothermic process.