This question is about some Period 3 elements and their oxides. 1. Write an equation for the reaction of phosphorus with an excess of oxygen. 2. Describe a test you could carry out in a test tube to distinguish between sodium oxide and the product of the reaction in Question 6.1. 3. State the type of crystal structure shown in silicon dioxide and sulfur trioxide. Silicon dioxide Sulfur trioxide 4. Explain why silicon dioxide has a higher melting point than sulfur trioxide. 5. Write an equation for the reaction of sulfur trioxide with potassium hydroxide solution. 6. Write an equation for the reaction of an excess of magnesium oxide with phosphoric acid. 7. Draw the displayed formula of the undissociated acid formed when sulfur dioxide reacts with water.

A-Level AQA Chemistry Periodicity: This question is about some Peri

This question is about some Period 3 elements and their oxides - AQA - A-Level Chemistry - Question 6 - 2017 - Paper 1

Question 6

This question is about some Period 3 elements and their oxides. 1. Write an equation for the reaction of phosphorus with an excess of oxygen. 2. Describe a test yo... show full transcript

Worked Solution & Example Answer:This question is about some Period 3 elements and their oxides - AQA - A-Level Chemistry - Question 6 - 2017 - Paper 1

Step 1

Write an equation for the reaction of phosphorus with an excess of oxygen.

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Answer

The reaction can be represented as:

$4P + 5O_2 \rightarrow 2P_2O_5$

Step 2

Describe a test you could carry out in a test tube to distinguish between sodium oxide and the product of the reaction in Question 6.1.

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Answer

To distinguish between sodium oxide and phosphoric oxide, you could use a pH indicator or universal indicator. Sodium oxide is basic and will turn the solution purple when dissolved in water, whereas phosphoric oxide will show a lower pH (acidic).

Step 3

State the type of crystal structure shown in silicon dioxide and sulfur trioxide.

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Answer

Silicon dioxide: Giant covalent (molecular) structure.

Sulfur trioxide: Molecular (simple) molecule.

Step 4

Explain why silicon dioxide has a higher melting point than sulfur trioxide.

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Answer

Silicon dioxide has a higher melting point than sulfur trioxide because it has a giant covalent structure with strong covalent bonds that require a lot of energy to break. In contrast, sulfur trioxide has weak molecular interactions, making it easier to melt.

Step 5

Write an equation for the reaction of sulfur trioxide with potassium hydroxide solution.

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Answer

The reaction can be expressed as:

$SO_3 + 2KOH \rightarrow K_2SO_4 + H_2O$

Step 6

Write an equation for the reaction of an excess of magnesium oxide with phosphoric acid.

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Answer

The reaction can be represented as:

$3MgO + 2H_3PO_4 \rightarrow Mg_3(PO_4)_2 + 3H_2O$

Step 7

Draw the displayed formula of the undissociated acid formed when sulfur dioxide reacts with water.

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Answer

The displayed formula of sulfurous acid is:

   H
   |
HO-S-OH
   |
   O

This question is about some Period 3 elements and their oxides - AQA - A-Level Chemistry - Question 6 - 2017 - Paper 1

Worked Solution & Example Answer:This question is about some Period 3 elements and their oxides - AQA - A-Level Chemistry - Question 6 - 2017 - Paper 1

Write an equation for the reaction of phosphorus with an excess of oxygen.

Describe a test you could carry out in a test tube to distinguish between sodium oxide and the product of the reaction in Question 6.1.

State the type of crystal structure shown in silicon dioxide and sulfur trioxide.

Explain why silicon dioxide has a higher melting point than sulfur trioxide.

Write an equation for the reaction of sulfur trioxide with potassium hydroxide solution.

Write an equation for the reaction of an excess of magnesium oxide with phosphoric acid.

Draw the displayed formula of the undissociated acid formed when sulfur dioxide reacts with water.

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