[OCR] 1

Topic: Chemical Bonding 2

Full question text, e.g ![img-0.jpeg](img-0.jpeg) particle A... particle B... [13.0m]

Part 1: (a) (i) Write an equation to represent the fourth ionisation energy of boron. [1m]

Your Answer:

Part 2: (a) (ii) Explain why the fourth ionisation energy of boron is much higher than that of carbon. [2m]

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Part 3: (b) (i) Draw a dot-and-cross diagram of the $BH_{3}$ molecule. [1m]

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Part 4: (b) (ii) State the shape and bond angle in $BH_{3}$. [1m]

Your Past Submissions

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Part 5: (b) (iii) Use the data in Table 1.1, together with data from the Data Booklet, to calculate the enthalpy change, $\Delta H_{r}$ for the reaction in equation 1. [2m]

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Part 6: (b) (iv) Explain why the standard enthalpy change of combustion of borane, $BH_{3}(g)$, is more exothermic than $\Delta H_{r}$. [2m]

Your Answer:

Part 7: (c) (i) Explain why $A/C/3$ can undergo dimerisation. [1m]

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Part 8: (c) (ii) By considering the shape around the $A/$ atom, state the change in hybridisation of the $A/$ atom when $A/C/3$ dimerises to $A/2 C/6$. [1m]

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Part 9: (c) (iii) The central hydrogen atoms, $H_{b}$, bond to both boron atoms. Explain why the $B-H_{b}$ bond is longer than $B-H_{a}$ bond. [2m]

Your Answer:

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[OCR] 1

Part 1: (a) (i) Write an equation to represent the fourth ionisation energy of boron. [1m]

Your Answer

Marking Points

Part 2: (a) (ii) Explain why the fourth ionisation energy of boron is much higher than that of carbon. [2m]

Your Answer

Marking Points

Part 3: (b) (i) Draw a dot-and-cross diagram of the $BH_{3}$ molecule. [1m]

Your Answer

Marking Points

Part 4: (b) (ii) State the shape and bond angle in $BH_{3}$. [1m]

Your Past Submissions

Your Answer

Marking Points

Part 5: (b) (iii) Use the data in Table 1.1, together with data from the Data Booklet, to calculate the enthalpy change, $\Delta H_{r}$ for the reaction in equation 1. [2m]

Your Answer

Marking Points

Part 6: (b) (iv) Explain why the standard enthalpy change of combustion of borane, $BH_{3}(g)$, is more exothermic than $\Delta H_{r}$. [2m]

Your Answer

Marking Points

Part 7: (c) (i) Explain why $A/C/3$ can undergo dimerisation. [1m]

Your Answer

Marking Points

Part 8: (c) (ii) By considering the shape around the $A/$ atom, state the change in hybridisation of the $A/$ atom when $A/C/3$ dimerises to $A/2 C/6$. [1m]

Your Answer

Marking Points

Part 9: (c) (iii) The central hydrogen atoms, $H_{b}$, bond to both boron atoms. Explain why the $B-H_{b}$ bond is longer than $B-H_{a}$ bond. [2m]

Your Answer

Marking Points

Review

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