Limiting Reagents and Redox reactions - Introduction

When two substances react to form products, the reactant which is used up is called the

• Determining reagent

• Limiting reagent

• Excess reagent

• Reactive reagent

Pentacarbonyliron [Fe(CO)₅] reacts with phosphorous trifluoride (PF₃) and hydrogen, releasing carbon monoxide:

Fe(CO)₅ + PF₃ + H₂ →→ [Fe(CO)₂(PF₃) (H₂)] + CO (not balanced)

The reaction of 5.0 mol of Fe(CO)₅, 8.0 mol of PF₃, and 6.0 mol of H₂ will release mol of CO

• 18

• 24

• 15

• 25

Which of the following is NOT a true statement about "yield"?

• The value of the actual yield must be given in order for the percent yield to be calculated.

• The actual yield is often less than the theoretical yield.

• The percent yield is the ratio of the actual yield to the theoretical yield.

• The actual yield may be different from the theoretical yield because reactions do not always go to completion.

• The actual yield may be different from the theoretical yield because insufficient limiting reagent was used.

Which of the following is not a reason why actual yield is less than theoretical yield?

• Impure reactants

• Competing side reactions

• Loss of product during purification

• Conservation of mass

Sulfur and fluorine react in a combination reaction to produce sulfur hexafluoride:

S(s) + 3F₂​(g)→ SF₆​(g)

The maximum amount of SF₆​ that can react with 3.5 g of sulfur with 4.5 g of fluorine is __ grams.

• 4.6

• 5.8

• 10.6

• 2.7

Solid aluminum and gaseous oxygen react in a combination reaction to produce aluminum oxide:

4Al (s) + 3O₂ ​(g)→2Al₂​O₃ ​(s)

The maximum amount of Al₂O₃ that can be produced from 2.5 g of Al and 2.5 g of O₂ is

• 2.35

• 4.7

• 6.8

• 9.4

• 100

• 250

• 150

• 200

• 0.114

• 0.0378

• 0.429

• 0.0756

How many grams of chromium (A= 52 amu) are needed to react with an excess of CuSO₄, to produce

27.0 g Cu (A= 63.5 amu)?

2Cr (s) + 3CuSO₄ (aq.) → Cr₂(SO₄)₃ (aq.) + 3Cu(s)

• 48.0 g

• 14.7 g

• 33.2 g

• 81.5 g

• 16.72

• 0.2

• 6.8

• 0.05