a 70 g sample of cesium is sealed in a glass vial and lowered into 250 mL of water at 90 C. when the cesium melted the temperature of the water dropped to 88.98 C

70.0 g  = .53 mol  

Q = 250g (+ 1.02) 4.18

Q = 1065. 9 J / 1000 = 1.0659 kJ

1.0659/ .53 = 2.01 kJ/ mol

2.01 kJ/ mol

Explanation:

answers: to make sure that all of the broken pieces of tablet were added to the water, to allow for fair comparison of all three trials, with different particle sizes to avoid experimental error