Question

По термохимическому кравнению H2+Br2=2HBr+66.8 кДЖ рассчитать массу брома, вступившего в реакцию, если при этом выделилось 3,34 кДж теплоты.

Answer 1

за х принимаем массу брома, 160 - отн.молек.масса брома

х : 160 = 3.34 : 66.8

х = 8  г

Answer 2

Calculation of the Mass of Bromine

To calculate the mass of bromine that reacted in the given thermochemical equation, we need to use the concept of stoichiometry. The stoichiometry of a chemical equation relates the number of moles of reactants and products.

The balanced equation for the reaction is:

H2 + Br2 → 2HBr + 66.8 kJ

From the equation, we can see that 1 mole of bromine (Br2) reacts to form 2 moles of hydrogen bromide (HBr). We can use this information to calculate the number of moles of bromine that reacted.

To calculate the number of moles of bromine, we can use the following equation:

moles of bromine = (moles of hydrogen bromide * molar mass of bromine) / stoichiometric coefficient of bromine

Since we know the amount of heat released during the reaction (3.34 kJ), we can use the equation:

heat released = moles of hydrogen bromide * enthalpy change of the reaction

To find the moles of hydrogen bromide, we can rearrange the equation:

moles of hydrogen bromide = heat released / enthalpy change of the reaction

Now, let's substitute the given values into the equation:

moles of hydrogen bromide = 3.34 kJ / 66.8 kJ

moles of hydrogen bromide = 0.05 moles

Since the stoichiometric coefficient of bromine is 1 in the balanced equation, the moles of bromine that reacted is also 0.05 moles.

To calculate the mass of bromine, we can use the equation:

mass of bromine = moles of bromine * molar mass of bromine

To find the molar mass of bromine, we can refer to the periodic table, which gives the molar mass of bromine as approximately 79.9 g/mol.

Now, let's substitute the values into the equation:

mass of bromine = 0.05 moles * 79.9 g/mol

mass of bromine = 3.995 g

Therefore, the mass of bromine that reacted in the given reaction is approximately 3.995 grams.