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1 1 g of CaCI2 dissolved in 50 cm3 of water cau... - JAMB Chemistry 1991 Question

1.1 g of CaCI2 dissolved in 50 cm3 of water caused a rise in temperature of3.4°C. The heat of reaction, ∆H for CaCI2 in kj per mole is?

(Ca = 40, CI = 35.5, specific heat of water is 4.18 jk-1
A
-71.1
B
-4.18
C
+71.1
D
+111.0
correct option: a
Q = mct = (50 x 4.18 x 3.4) / (1000)
= 0.71606 kj
1.1 g of call2 contains
(1.1) / (111) = 0.01 moles of call2
If 0.01 liberates 0.7106 RS
1 will liberate (0.7106 x 1) / (0.01)
Endothermic = 71.06 = -71.1
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