The meals-ready-to-eat (MREs) in the military can be heated on a flameless heater. You can purchase a similar product called "Heater Meals." Just pour water into the heater unit, wait a few minutes, and you have a hot meal. The source of energy in the heater is Mg(s) + 2 H₂O(l) → Mg(OH)2 (s) + H₂(g) Calculate the enthalpy change under standard conditions, in joules, for this reaction. What quantity of magnesium is needed to supply the energy required to warm 30. mL of water (d = 1.00 g/mL) from 24 °C to 85 °C? The specific heat capacity of water is 4.184 J/g. °C. AH (kJ/mol) Compound Mg(OH)2 (s) H₂O(l) -924.54 -285.83 The "heater meal" uses the reaction of magnesium with water as a source of energy as heat. Enthalpy change = J/mol-rxn g Mg

Measurements show that the energy of a mixture of gaseous reactants decreases by 373. kJ during a certain chemical reaction, which is carried out at a constant pressure. Furthermore, by carefully monitoring the volume change it is determined that 136. kJ of work is done on the mixture during the reaction. Calculate the change in enthalpy of the gas mixture during the reaction. Round your answer to 3 x10 significant digits. exothermic Is the reaction exothermic or endothermic? endothermic

A 56.5 g sample of iron is put into a calorimeter (see sketch at right) that contains 300.0 g of water. The iron sample starts off at 86.7 °C and the temperature of the water starts off at 21.0 °C. When the temperature of the water stops changing it's 22.8 °C. The pressure remains constant at 1 atm. Calculate the specific heat capacity of iron according to this experiment. Be sure your answer is rounded to 2 significant digits. J 0₂-C x10 x thermometer insulated container water sample a calorimeter

The molar heat of solution of a substance is found to be +21.38 kJ/mol. The addition of 0.100 mol of this substance to 1.000L of water initially at 40.0 degrees celsius results in a temperature decrease. Assume the specific heat of the resulting solution to be equal to that of pure water. Find the final temperature of the solution (Also assume that the heat capacity of the calorimeter is negligible).

A 56.1 g sample of polystyrene, which has a specific heat capacity of 1.880 J-g °C-1 is put into a calorimeter (see sketch at right) that contains 250.0 g of water. The temperature of the water starts off at 24.0 °C. When the temperature of the water stops changing it's 29.8 °C. The pressure remains constant at 1 atm. Calculate the initial temperature of the polystyrene sample. Be sure your answer is rounded to the correct number of significant digits. °C thermometer. insulated container water sample. a calorimeter 區 OU Ar

A 54.5 g sample of brass is put into a calorimeter (see sketch at right) that contains 300.0 g of water. The brass sample starts off at 95.8 °C and the temperature of the water starts off at 15.0 °C. When the temperature of the water stops changing it's 16.4 °C. The pressure remains constant at 1 atm. Calculate the specific heat capacity of brass according to this experiment. Be sure your answer is rounded to 2 significant digits. П J g.°C x10 X S thermometer insulated container water sample a calorimeter U!!! 0 C

A bomb calorimeter, or a constant volume calorimeter, is a device often used to determine the heat of combustion of fuels and the energy content of foods. In an experiment, a 0.3215 g sample of phenanthrene (C14H10) is burned completely in a bomb calorimeter. The calorimeter is surrounded by 1.162×10 g of water. During the combustion the temperature increases from 25.15 to 27.48 °C. The heat capacity of water is 4.184 J glc-!. The heat capacity of the calorimeter was determined in a previous experiment to be 769.3 J/°C. Assuming that no energy is lost to the surroundings, calculate the molar heat of combustion of phenanthrene based on these data. C14H10(s) + (33/2) O,(g) – → 5 H,O(1) + 14 CO2(g) + Energy Molar Heat of Combustion = kJ/mol

A 57.1 g sample of polystyrene, which has a specific heat capacity of 1.880 J-g¹C, is put into a calorimeter (see sketch at right) that contains 100.0 g of water. The temperature of the water starts off at 23.0 °C. When the temperature of the water stops changing it's 38.3 °C. The pressure remains constant at 1 atm. Calculate the initial temperature of the polystyrene sample. Be sure your answer is rounded to 3 significant digits. 0°C 0...º X

A student is attempting to determine the heat capacity of a Styrofoam cup calorimeter by pouring hot water into a Styrofoam cup containing cold water. The student determined the mass of the cold water to be 21.2455 g and its initial temperature to be 20.36 °C. The mass of the hot water was 24.2646 g and its initial temperature as 34.54 °C. The final temperature of the water after mixing was determined to be 24.57°C. The specific heat capacity of the water is 4.184 J/(g•°C). What is the heat capacity of the Styrofoam cup calorimeter? Assume the temperature of the calorimeter is the same temperature as the cold water. 4.184 J/°C 132.5 J/°C

Measurements show that the energy of a mixture of gaseous reactants decreases by 374. kJ during a certain chemical reaction, which is carried out at a constant pressure. Furthermore, by carefully monitoring the volume change it is determined that 176. kJ of work is done on the mixture during the reaction. Calculate the change in enthalpy of the gas mixture during the reaction. Round your answer to 3 significant digits. Is the reaction exothermic or endothermic? kJ exothermic endothermic 0x1 x10 X Ś