A simple model of the atom, symbols, relative atomic mass, electronic charge and isotopes

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Question 6
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This question is about chromium and its extraction.

a.

Chromium is a transition metal. Match each property of chromium to the correct reason for that property.

Properties:

  • Conducts heat/electricity
  • High melting point

Reasons:

  • Chromium has delocalised electrons
  • Chromium has layers of atoms which can slide
  • Chromium has strong metallic bonds
  • Chromium has weak intermolecular forces
  • Chromium has a random arrangement of atoms
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b.

Chromium can be mixed with iron and carbon to make stainless steel. What is meant by an 'alloy'?

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c.

Chromite is an ore containing chromium(III) oxide. Chromite ore samples contain between 15% and 35% chromium. Pure chromium(III) oxide always contains 68.4% chromium. How does this show that chromite ore is a mixture and not a compound?

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d.

In one stage of chromium extraction, sodium dichromate, Na2Cr2O7\text{Na}_2\text{Cr}_2\text{O}_7Na2​Cr2​O7​, is used. Give the total number of atoms in the formula unit of Na2Cr2O7\text{Na}_2\text{Cr}_2\text{O}_7Na2​Cr2​O7​.

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e.

A sample of chromite ore contains 28% chromium. Calculate the maximum mass of chromium that can be extracted from 350,000 kg350,000\text{ kg}350,000 kg of this sample of chromite. Give your answer in standard form.

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A simple model of the atom, symbols, relative atomic mass, electronic charge and isotopes Questions

  1. GCSE
  2. /Chemistry
  3. /A simple model of the atom, symbols, relative atomic mass, electronic charge and isotopes