August 2009 Chemistry Regents #51-55

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Questions 51-55

 

51 Identify the element in Period 3 of the Periodic Table that reacts with oxygen to form an ionic compound represented by the formula X2O. [1]

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Sodium or Na

52 Given the balanced equation representing a reaction:

2C2H6 + 7O2==>4CO2 + 6H2O

Determine the total number of moles of oxygen that react completely with 8.0 moles of C2H6. [1]

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Answer=28 moles

(Set up a proportion 8.0/2C2H6  = X/7O2)

53 On the potential energy diagram in your answer booklet, draw an arrow to represent the activation energy of the forward reaction. [1]

LINK TO ANSWER 53

54 Describe the electrons in an atom of carbon in the ground state. Your response must include:

the charge of an electron [1]

the location of electrons based on the wave-mechanical model [1]

the total number of electrons in a carbon atom [1]

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Allow 1 credit for stating that an electron has a negative charge.

Allow 1 credit for stating that electrons are located in orbitals or regions of most probable location.

Allow 1 credit for stating that a carbon atom has six electrons.

55 Determine the mass of 5.20 moles of C6H12 (gram-formula mass = 84.2 grams/mole). [1]

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Answer=438g

mass=5.20mol x 84.2g/mol

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Questions 51-55 Questions56-58 Questions 59-63 Question 64 Questions 65-67 Questions 68-72 Questions 73-76 Questions 77-79 Questions 80-81

 
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