The initial temperature of the water in a constant-pressure calorimeter is 14°C. A reaction takes place in the calorimeter, and the temperature rises
to 87°C. The calorimeter contains 254 g of water, which has a specific heat
of 4.18 J/(g.°C). Calculate the enthalpy change during this reaction. *

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The atomic radius of sodium is 186 pm and of chlorine is 100 pm. the ionic radius for na+ is 102 pm and for cl– is 181 pm. in going from na to cl in period 3, why does the atomic radius decrease while the ionic radius increases? a. the inner electrons in the sodium cation shield its valence electrons more effectively than the inner electrons in the chloride anion do. b. the inner electrons shield the valence electrons more effectively in the chlorine atom than in the chloride anion. c. the outermost electrons in chloride experience a smaller effective nuclear charge than those in the sodium cation do. d. the outermost electrons in chloride experience a larger effective nuclear charge than those in the sodium cation do. e. monatomic ions are bigger than the atoms from which they are formed.

Which position represents spring in the southern hemisphere? a) b) c) d)