Which observation helps distinguish iron(II) from iron(III) when reacting with sodium hydroxide?

Unlock all questions

This demo includes only 20 questions. Upgrade to access hundreds of questions, flashcards, exam simulations, and disable ads.

Full question bankExam simulationsFlashcards
From $24.99Unlock all

Study for the IGCSE Edexcel Chemistry Test. Access flashcards and multiple choice questions with hints and explanations. Get ready for your exam!

Multiple Choice

Which observation helps distinguish iron(II) from iron(III) when reacting with sodium hydroxide?

Explanation:
When you add sodium hydroxide to solutions of these iron ions, you’re looking at the different iron hydroxide solids that form because the two oxidation states make different compounds. Fe2+ precipitates as Fe(OH)2, which is a pale green solid. Fe3+ precipitates as Fe(OH)3, which appears orange-brown. So the color of the precipitate reveals the oxidation state: green means iron(II), orange-brown means iron(III). (Keep in mind Fe2+ can slowly oxidize to Fe3+ in air, so the green precipitate may darken over time if left exposed.)

When you add sodium hydroxide to solutions of these iron ions, you’re looking at the different iron hydroxide solids that form because the two oxidation states make different compounds. Fe2+ precipitates as Fe(OH)2, which is a pale green solid. Fe3+ precipitates as Fe(OH)3, which appears orange-brown. So the color of the precipitate reveals the oxidation state: green means iron(II), orange-brown means iron(III). (Keep in mind Fe2+ can slowly oxidize to Fe3+ in air, so the green precipitate may darken over time if left exposed.)

More Multiple Choice Questions
Subscribe

Get the latest from Examzify

You can unsubscribe at any time. Read our privacy policy