Chemistry T.2 final revision

What is the increase in oxidation number for the atom that is oxidized in the following balanced redox equation?

Cr₂O₇ ^2– + 8H⁺ + 3SO₃ ^2– → Cr ³⁺ + 3SO₄ ^2– + 8H^₂O

• +6

• +2

• -2

• +4

To balance the oxygen and hydrogen for a redox reaction that takes place in basic solution, it is necessary to use

• . H₂O and OH^–.

  
  

• H₂O and H⁺

  
  

• OH^– only

  
  

• H₂O only

  
  

Which of the following is an oxidation half-reaction?

• 2H⁺ + 2e^– → H₂

  
  

• Zn²⁺ + 2e^– → Zn

  
  

• Na⁺ + e^– → Na

  
  

• NO + 2H₂O → NO₃^– + 4H⁺ + 3e^–

  
  

What is the reduction half-reaction for the following unbalanced redox equation?

Cr₂O₇^2– + Fe²⁺ → Cr³⁺ + Fe³⁺

• Cr³⁺ → Cr₂O₇^2–

  
  

• Cr₂O₇^2– → Cr³⁺

  
  

• Fe³⁺ → Fe²⁺

  
  

• Fe²⁺ → Fe³⁺

  
  

Which atom is reduced in the following unbalanced redox equations?

K₂Cr₂O₇ + H₂O + S → KOH + Cr₂O₃ + SO₂

• S

• Cr

• O

• K

If 1 Calorie = 4.18 kJ, how many kJ of energy can be released by an apple containing 125 Cal?

• 522 kJ

  
  

• 0.0334 kJ

  
  

• 29.9 kJ

  
  

• 5.22 × 105 kJ

  
  

The temperature of a 6.0-g sample of glass changed from 20°C to 45°C when it absorbed 550 J of heat. What is the specific heat of this glass sample?

• 2300 J/g•°C

  
  

• 0.27 J/g•°C

  
  

• 3.7 J/g•°C

  
  

• 130 J/g•°C

  
  

When your body(system) is warmed by an electric blanket(surrounding) during the winter, this process is said to be…………

• isothermic

  
  

• endothermic

  
  

• exothermic

  
  

• no answer is correct

  
  

How many calories are required to raise the temperature of 75.0 g of water from 20°C to 50°C?

(specific heat of water = 1 cal/g.°C)

• 75.0 cal

  
  

• 3750 cal

  
  

• 1.50 × 103 cal

  
  

• 2250 cal

  
  

Which sentence is true about heat?

• Heat always flows from a cooler object to a warmer object.

  
  

• If two objects remain in contact, heat will flow from the warmer object to the cooler object until the temperature of both objects is the same.