Question

Уравнение: 2H2O=2H2+О2-572кДж Сколько теплоты затрачивается на разложение 52г воды? Какой объем водорода при этом выделяется?

Answer 1

2H2O=2H2+О2-572кДж
По уравнению реакции на 2 моль воды затрачивается 572 кДж теплоты.
Найдем количество вещества воды, данное нам:
n = m/M = 52/18 = 2.89 моль
Составим пропорцию:
2,89 моль - х кДж
2 моль - 572 кДж
Значит х = 572*2,89/2 = 826,2 кДж затрачивается на разложение 52 г воды.
Найдем объем водорода.
По реакции его столько же, сколько и воды, т.е. 2,89 моль.
Объем найдем по формуле:
V = n*Vm = 2.89*22.4 = 64.74 л

Answer 2

Background Information

The equation given is the balanced chemical equation for the decomposition of water into hydrogen gas (H2) and oxygen gas (O2). The reaction is exothermic, meaning it releases energy in the form of heat. The value of -572 kJ represents the heat released per mole of water decomposed.

Calculation of Heat Released

To calculate the amount of heat released when 52 g of water decomposes, we need to convert the mass of water to moles and then multiply it by the heat released per mole.

1. Calculate the number of moles of water: - The molar mass of water (H2O) is 18.015 g/mol. - Divide the mass of water (52 g) by the molar mass to get the number of moles: 52 g / 18.015 g/mol = 2.884 mol.

2. Calculate the heat released: - Multiply the number of moles of water by the heat released per mole (-572 kJ/mol): 2.884 mol * -572 kJ/mol = -1649.648 kJ.

Therefore, when 52 g of water decomposes, 1649.648 kJ of heat is released.

Calculation of Hydrogen Gas Volume

To calculate the volume of hydrogen gas produced when 52 g of water decomposes, we need to use the ideal gas law and the molar volume of a gas at standard temperature and pressure (STP).

1. Calculate the number of moles of hydrogen gas: - According to the balanced chemical equation, 2 moles of hydrogen gas are produced for every 2 moles of water decomposed. - Since the number of moles of water decomposed is 2.884 mol (as calculated earlier), the number of moles of hydrogen gas produced is also 2.884 mol.

2. Calculate the volume of hydrogen gas at STP: - The molar volume of a gas at STP is 22.4 L/mol. - Multiply the number of moles of hydrogen gas by the molar volume: 2.884 mol * 22.4 L/mol = 64.6336 L.

Therefore, when 52 g of water decomposes, 64.6336 L of hydrogen gas is produced.

Please note that these calculations assume ideal conditions and may not account for factors such as non-ideal behavior of gases or deviations from STP.