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1. A 4.2g sample of CaCO3 is added to 170.2g of 1.0M HCI. The temperature rises

ID: 551037 • Letter: 1

Question

1. A 4.2g sample of CaCO3 is added to 170.2g of 1.0M HCI. The temperature rises from 24.0 to 26.0 Assuming that the specific heat capacity, s, of the solution is 4.18 J/(gx oC) and the density of the solution is 1.00g/mL, calculate the heat produced by the reaction. NaF (s) :-575.4 k/mol Consider the following reaction: a. Is the reaction exothermic or endothermic? b. How much energy is released or absorbed when 0.56g of Na reacts with excess F2? 2. Na(s) + ½F2(g) 3. Determine the enthalpy, AHran for the following reaction Given the following information: O2(g) 302(g) S(s) + SO2(g) H =-296.8 kJ 25(s) 2SO3(g) +

Explanation / Answer

1. Density of solution = 1g/ml

Therefore,

Mass of solution = 170.2g × 1 = 170.2g

Heat absorbed by the solution is q

q = m × T × C

m= 170.2g

T = 26 - 24 = 2

C = 4.184J/g

q = 170.2g × 2 × 4.184J/g

= 1424J

Heat absorbed by solution = Heat produced by the reaction

Therefore,

1424J of Heat is produced during this reaction

2. a) This reaction exothermic

b) No of mole of Na = 0.56g/23g/mol = 0.02435

This reaction is exothermic reaction

Therefore,

Heat release = -575.4kJ × 0.02435 = -14.01kJ

3. SO2(g) + 1/2O2(g) ------> SO3(g)

Hrxn = Hf( products ) - Hf ( reactants )

= (1× Hf(SO3)) - (1×Hf(SO2) + 1/2 × Hf(O2))

=( 1×( -397.7kJ) ) - ( (1× -296.8kJ) + 1/2 × 0 )

= -397.7kJ + 296.8

= -100.9kJ