International ASChemistryEdexcelExam Questions1. Structure, Bonding & Introduction to Organic Chemistry1.2 Amount of Substance

Amount of Substance (Edexcel International AS Chemistry)

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1.2 Amount of Substance

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1.2 Amount of Substance

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1a
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This question is about silicon and carbon.

Silicon is a semiconductor.

i)

Data obtained using the mass spectrum of silicon are shown.

Isotope mass number Relative abundance
28 92.17
29 4.71
30 3.12

Calculate the relative atomic mass of silicon to two decimal places.

(2)

ii)
Suggest a reason why there is a small peak in the mass spectrum of silicon at m / z = 14

(1)

iii)
Complete the table to show the number of protons and neutrons in each isotope of silicon.

Isotope Number of protons Number of neutrons
28Si    
29Si    
30Si    

(1)

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1b3 marks

Silicon dioxide, SiO2 , is the main constituent of sand and has a giant lattice structure similar to that of diamond.

q13b-paper-1-oct-2021-edexcel-ial-chemistry

Crystalline silicon dioxide is used on the surface of semiconductor devices to provide a heat-resistant, electrically insulating layer.

Explain how the structure and bonding of silicon dioxide make it useful for this application.

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1c
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Calcium silicate is formed in the removal of silicon dioxide impurities in the extraction of iron from its ores. A sample of calcium silicate composed of calcium, silicon and oxygen was found to contain 12.0 g of calcium, 8.43 g of silicon and 14.47 g of oxygen.

Determine the empirical formula of calcium silicate.
You must show your working.

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1d
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Carbon dioxide is a gas at room temperature. A fizzy drink is canned at 5.0°C and 1.3 × 105 Pa and contains approximately 3 g of carbon dioxide.

Calculate the volume, in cm3, occupied by 3.00 g of carbon dioxide gas at 5.0°C and 1.3 × 105 Pa.

[pV = nRT     R = 8.31 Jmol−1K−1]

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2a
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A 0.210 g sample of a volatile organic liquid C is injected into a gas syringe and heated in an oven.
At 100 kPa and 358 K, the syringe contains 72.5 cm3 of gas.

Calculate the molar mass of C.
[pV = nRT        R = 8.31 J mol−1 K−1 ]

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2b
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The organic liquid C is a hydrocarbon.
Give a possible name or formula for C, using your answer in (a).

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1a
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The hydride of arsenic, arsine, is a toxic gas used in the production of semiconductors.

Draw a dot‐and‐cross diagram for arsine, AsH3.

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1b
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Arsine is a reducing agent and reacts with cerium(IV) sulfate solution, forming arsenic.

The data from an experiment are shown.

Volume of arsine gas = 350 cm3 at 115000 Pa and 20 °C

Volume of cerium(IV) sulfate solution = 488 cm3

Concentration of cerium(IV) sulfate solution = 0.102 mol dm−3

i)
Complete the half‐equation.

(1)

AsH3 → As

ii)
Calculate the final oxidation state of the cerium ion formed in the reaction.

(6)

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