posted by Lance .
Hydrogen is burned in oxygen to release heat. How many grams of hydrogen gas must be burned to release enough heat to warm a 50.0 g block of iron, giving 5 mol of water?
2 H2(g) + O2(g) → 2 H2O(g) ΔH = −484 kJ
Iron has a specific heat of 0.449 J/(g·°C).