Chemistry 9701/41 — May/June 2010

Cambridge A-Level · Paper 4 Structured Questions · worked solutions for every part, with the mark scheme

questions

100

marks

105

minutes

Topics Nitrogen Compounds · Introduction to A Level Organic Chemistry · Carboxylic Acids and Derivatives · Electrochemistry · Hydroxy Compounds · Transition Elements · +6 more

Q1Nitrogen CompoundsFree sample

(a)

Phosphorus and sulfur are two non-metallic elements on the right hand side of the Periodic Table.
For each of these elements describe the observations you would make when it burns in air, and write a balanced equation for the reaction.

phosphorus

observation

equation

sulfur

observation

equation

(b)

White phosphorus, $\text{P}_4$ , is produced commercially by heating calcium phosphate(V) rock with a mixture of silica, $\text{SiO}_2$ , and coke in an electric furnace at $1400\text{ }^{\circ}\text{C}$ . Calcium silicate, $\text{CaSiO}_3$ , and carbon monoxide are the other products.

(i)

Balance the following equation which represents the overall process.

\text{\_\_\_ }\text{Ca}_3(\text{PO}_4)_2 + \text{\_\_\_ }\text{SiO}_2 + \text{\_\_\_ }\text{C} \rightarrow \text{\_\_\_ }\text{P}_4 + \text{\_\_\_ }\text{CaSiO}_3 + \text{\_\_\_ }\text{CO}

(ii)

When heated to $400\text{ }^{\circ}\text{C}$ in the absence of air, white phosphorus is changed into the red form of the element. The following table lists some of the properties of the two forms, which are known as allotropes.

allotrope	electrical conductivity	melting point / $^{\circ}\text{C}$	solubility in water	solubility in benzene
white	none	44	insoluble	soluble
red	none	500	insoluble	insoluble

Suggest the type of structure and bonding in each allotrope.

allotrope	type of structure	type of bonding
white
red

(iii)

In both allotropes, phosphorus has a valency of 3. Suggest by means of diagrams how the phosphorus atoms might be joined together in each allotrope.

Fig. 1.1

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9 more questions

Q2Transition Elements10M
Q3Electrochemistry · Introduction to A Level Organic Chemistry8M
Q4Introduction to A Level Organic Chemistry · Hydroxy Compounds · Nitrogen Compounds · Organic Synthesis12M
Q5Electrochemistry · Group 211M
Q6Carboxylic Acids and Derivatives · Polymerisation · Introduction to A Level Organic Chemistry · Nitrogen Compounds12M
Q7Hydrocarbons · Halogen Compounds · Hydroxy Compounds · Carboxylic Acids and Derivatives6M
Q8Nitrogen Compounds10M
Q9Analytical Techniques · Carboxylic Acids and Derivatives10M
Q10Carboxylic Acids and Derivatives · Introduction to A Level Organic Chemistry10M

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