A 54.7 g sample of arsenic tribromide was heated until the compound melted. The molten compound was then poured into a calorimeter containing 300.0 g water at 22.50 °C. When the last bit of the compound had solidified, the temperature of the water was 24.13 °C. This is called the molar heat of fusion of AsBr3. Calculate ΔH (per mole of AsBr3)

ΔH = - 11758.6 J/mol = - 11.76 kJ/mol

Explanation:

Step 1: Data given

Mass of arsenic tribromide = 54.7 grams

MAss of water = 300.0 grams

Temperature of water = 22.50 °C

Final temperature of water = 24.13 °C

Step 2: Calculate ΔH

Q= m*c*ΔT

⇒with m =the mass of water = 300.0 grams

⇒with c= the specific heat of water = 4.184 J/g°C

⇒with ΔT = the change in temperature of water = T2 - T2 = 24.13 - 22.50 = 1.63 °C

Q = 300 * 4.184 * 1.63

Q = 2046 J

Step 3: Calculate moles AsBr3

Moles AsBr3 = mass / molar mass

Moles AsBr3 = 54.7 grams /  314.634 g/mol

Moles AsBr3 = 0.174 moles

Step 4: Calculate ΔH

ΔH = -Q/moles

ΔH = -2046 J / 0.174 moles

ΔH = - 11758.6 J/mol = - 11.76 kJ/mol

the seeing the electronic configuration we can say that the element is fluorine.

fluorine is the most electronegative element in the periodic table.

but by only seeing the configuration we cannot say about its reactivity because we don't know if its configuration after excitation or by addition of electrons.

but if not then, it is the lightest halogen and exists as a highly toxic pale yellow diatomic gas at standard conditions. as the most electronegative element, it is extremely reactive: almost all other elements, including some noble gases, form compounds with fluorine.