Meals-ready-to-eat (MREs) are military meals that can be heated on a flameless heater. The heat is produced by the following reaction: Mg (s)  +  2 H2O (l)  ?  Mg(OH)2 (s)  +  H2 (g) ∆H = -355 kJ/mol Calculate the number of grams of Mg needed for this reaction to release enough energy to increase the temperature of 75 mL of water from 21ºC to 79ºC.

When 0.514 g of biphenyl, C12H10, undergoes combustion in a bomb calorimeter, the temperature rises from 25.8 C to 29.4 C. Find ∆Urxn for the combustion of biphenyl. The bomb calorimeter contains 750.0 mL of water and has a heat capacity of 2.72 kJ/C.

5.00 g of potassium hydroxide (molar mass = 56.1 g/mol) dissolves in 100.0 g of water and the temperature of the solution increases by 1.60oC. Calculate  ΔH for the reaction in kJ/mol of KOH .The specific heat capacity of the solution is 4.18 J/goC   ( Hint: the mass of the solution is 105g)      (Hint #2: is this + or -?) Your answer should be in kJ/mol and have 3 sig figs

In the following reaction, how much heat (in kJ) is released when 5.63 moles of CH₄ are burned? CH₄ (g) + 2 O₂ (g) → CO₂ (g) + 2 H₂O(g) ∆H° = -802 kJ/mol