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Ch.4 - Chemical Reactions and Chemical Quantities
Tro - Chemistry: A Molecular Approach 5th Edition
Tro5th EditionChemistry: A Molecular ApproachISBN: 9780134874371Non è quello che usi tu?Cambia libro di testo
Capitolo 4, Problema 31

Hydrobromic acid dissolves solid iron according to the reaction:
Fe(s) + 2 HBr(aq) → FeBr2(aq) + H2(g)
What mass of HBr (in g) do you need to dissolve a 3.2-g pure iron bar on a padlock? What mass of H2 would the complete reaction of the iron bar produce?

Guida verificata passo dopo passo
1
Determine the molar mass of iron (Fe) and hydrobromic acid (HBr).
Calculate the number of moles of iron in the 3.2-g iron bar using its molar mass.
Use the stoichiometry of the balanced chemical equation to find the moles of HBr needed. The equation shows that 1 mole of Fe reacts with 2 moles of HBr.
Convert the moles of HBr to grams using the molar mass of HBr.
Calculate the moles of H2 produced using the stoichiometry of the reaction, where 1 mole of Fe produces 1 mole of H2, and then convert this to grams using the molar mass of H2.

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Stoichiometry

Stoichiometry is the calculation of reactants and products in chemical reactions based on the balanced chemical equation. It allows us to determine the relationships between the amounts of substances involved in a reaction, using mole ratios derived from the coefficients in the balanced equation. In this case, it helps us find the mass of HBr needed to react with a given mass of iron and the mass of hydrogen gas produced.
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Stoichiometry Concept

Molar Mass

Molar mass is the mass of one mole of a substance, typically expressed in grams per mole (g/mol). It is essential for converting between the mass of a substance and the number of moles, which is necessary for stoichiometric calculations. For this problem, knowing the molar masses of iron (Fe) and hydrobromic acid (HBr) will allow us to calculate the required mass of HBr and the mass of hydrogen gas produced.
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Gas Laws

Gas laws describe the behavior of gases under various conditions of temperature and pressure. In this context, while the production of hydrogen gas (H2) is a result of the reaction, understanding gas laws can help predict how the gas behaves after formation. Although not directly required for mass calculations, it provides insight into the properties of the gas produced in the reaction.
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Combined Gas Law
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What mass of HBr (in g) do you need to dissolve a 3.2-g pure iron bar on a padlock?

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