Chapter 7 Stoichiometry

In 1901, Thomas Edison invented the nickel-iron battery. The following reaction takes place in the battery:

Fe(s) + 2NiO(OH)(s) + 2H₂O(l) → Fe(OH)₂(s) + 2Ni(OH)₂(aq) How many mol of Fe(OH)2 is produced when 5.00 mol of Fe and 8.00 mol of NiO(OH) react?

• 5.0 mol Fe(OH)₂

• 8.0 mol Fe(OH)₂

• 4.0 mol Fe(OH)₂

• 1.0 mol Fe(OH)₂

One of the few xenon compounds that form is cesium xenon heptafluoride (CsXeF₇). How many moles of CsXeF₇ can be produced from the reaction of 12.5 mol of cesium fluoride with 10.0 mol of xenon hexafluoride? CsF(s) + XeF₆(s) → CsXeF₇ (s)

• 10.0 mol CsXeF₇ (s)

• 11.0 mol CsXeF₇ (s)

• 7.5 mol CsXeF₇ (s)

• 2.5 mol CsXeF₇ (s)

The reaction of chlorine gas with solid phosphorus (P₄) produces solid phosphorus pentachloride. When 16.0 g of chlorine reacts with 23.0 g of P₄, which reactant is limiting? Which reactant is in excess?

• Chlorine is the limiting reactant; phosphorus is in excess.

• Chlorine is excess; phosphorus is the limiting reactant.

• Neither both are present in equal stoichiometric quantities.

• There is no limiting reagent both are in excess.

An alkaline battery produces electrical energy according to this equation.

Zn(s) + 2MnO₂(s) + H₂O(l) → Zn(OH)₂ (s) + Mn₂O₃(s) Determine the mass of Zn(OH)2 produced if 25.0 g of Zn and 30.0 g of MnO2 are used.

• 55.0 g Zn(OH)₂

• 25.0 g Zn(OH)₂

• 30.0 g Zn(OH)₂

• 17.1 g Zn(OH)₂

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NGSS.HS-PS1-7

An alkaline battery produces electrical energy according to this equation:

Zn(s) + 2MnO₂(s) + H₂O(l) → Zn(OH)₂ (s) + Mn₂O₃(s) Determine the limiting reactant if 25.0 g of Zn and 30.0 g of MnO2 are used

• H2O is the limiting reactant.

• MnO2 is the limiting reactant.

• All reactants are limiting, they are all in equal stoichiometric quantities.

• Zn is the limiting reactant.

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NGSS.HS-PS1-7

Lithium reacts spontaneously with bromine to produce lithium bromide. Write the balanced chemical equation for the reaction.

• 2Li + Br → Li₂Br

• Li + Br₂ → LiBr

• Li + Br → LiBr

• 2 Li + Br₂ → 2 LiBr

If 25.0 g of lithium and 25.0 g of bromine are present at the beginning of the reaction, determine the excess reactant and the excess mass.

• Li, 25.0 g

• Br, 22.8 g

• Br, 25.0 g

• Li, 22.8 g

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NGSS.HS-PS1-7

Ethanol (C₂H₅OH) is produced from the fermentation of sucrose (C₁₂H₂₂O₁₁) in the presence of enzymes. C₁₂H₂₂O₁₁ (aq) + H₂O(g) → 4C₂H₅OH(l) + 4CO₂(g) Determine the percent yield of ethanol if 684 g of sucrose undergoes fermentation and 349 g of ethanol is obtained.

• 94.6%

• 100%

• 34.9%

• 68.4%

Upon heating, calcium carbonate (CaCO₃) decomposes to calcium oxide (CaO) and carbon dioxide (CO₂). Determine the theoretical yield of CO₂ if 235.0 g of CaCO₃ is heated.

• 235 CO₂

• 103g CO₂

• 0g CO₂

• 23.5g CO₂

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NGSS.HS-PS1-7

2C(s) + FeCr₂O₄(s) → FeCr₂ (s) + 2 CO₂(g)

What mole ratio would you use to convert from moles of chromite to moles of ferrochrome?

• 1 mol FeCr₂ / 2 mol FeCr₂O₄

• 2 mol FeCr₂ / 1 mol FeCr₂O₄

• 1 mol FeCr₂ / 1 mol FeCr₂O₄

• 2 mol FeCr₂ / 2 mol FeCr₂O₄

Tags

NGSS.HS-PS1-7