In the presence of excess oxygen, methane gas burns in a constant-pressure system to yield carbon dioxide and water: CH4 (g) + 2O2 (g) → CO2 (g) + 2H2O (l) with ΔH = -890.0 kJ. Calculate the value of q (kJ) in this exothermic reaction when 1.70 g of CH4 is burned.

How much energy is released when 65.8 g of water freezes, given that the enthalpy of fusion for water is 6.01 kJ/mol?

How much heat (in kJ) is required to warm 11.0 g of ice, initially at -13.0 °C, to steam at 108.0 °C? The heat capacities of ice, water, and steam are 2.09, 4.18, and 2.01 J·g⁻¹·°C⁻¹, respectively. The enthalpy of fusion of ice is 334 J/g.

How much heat is released when one mole of steam (18.0 g) at 100.0 °C is converted to water at 25.0 °C?

If the aluminum block is initially at 25 °C, what is the final temperature of the block after the evaporation of the alcohol, assuming the heat required for the vaporization of the alcohol comes only from the aluminum block?

Which of the following is an endothermic process?

Sodium metal reacts with water to produce hydrogen gas and sodium hydroxide according to the chemical equation shown below. When 0.025 mol of Na is added to 100.00 g of water, the temperature of the resulting solution rises from 25.00°C to 35.75°C. If the reaction is exothermic, what is the sign of the enthalpy change (ΔH) for this reaction?

Sodium reacts violently with water according to the equation: 2 Na(s) + 2 H2O(l) → 2 NaOH(aq) + H2(g). The resulting solution has a higher temperature than the water prior to the addition of sodium. What are the signs of ΔH° and ΔS° for this reaction?

Suppose that 0.79 g of water condenses on a 95.0-g block of copper that is initially at 23 °C. If the heat released during condensation goes only to warming the copper block, what is the final temperature (in °C) of the copper block? Assume a constant specific heat capacity for copper.