How to do this question---**Question 11**
This question is about the reaction between magnesium and dilute nitric acid.
(a) A student reacts dilute nitric acid with an excess of magnesium powder as a first step in the preparation of dry crystals of hydrated magnesium nitrate.
This is the equation for the reaction.
Mg(s) + 2HNO₃(aq) → Mg(NO₃)₂(aq) + H₂(g)
(iii) Describe how the student can obtain dry crystals of hydrated magnesium nitrate from the mixture at the end of the reaction.
(5)
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In this chemistry question, we need to obtain dry crystals of hydrated magnesium nitrate from a reaction mixture. The reaction between magnesium and dilute nitric acid produces magnesium nitrate solution, hydrogen gas, and leaves excess magnesium powder in the mixture.
To obtain dry crystals, we follow a systematic process. First, filter the mixture to remove excess magnesium powder. This gives us a clear solution of magnesium nitrate. Then we heat the solution to evaporate some water and concentrate it. Finally, we cool the solution slowly to allow crystals to form.
To summarize the complete method: filter to remove excess magnesium, heat to concentrate the solution, cool slowly for crystallization, filter to collect crystals, wash with distilled water, and finally dry the crystals. This process yields pure, dry crystals of hydrated magnesium nitrate.
The next crucial steps involve heating and cooling. Heat the filtered solution to evaporate water and create a saturated solution. Then cool slowly to allow crystals to form. Slow cooling produces larger, better-quality crystals. Finally, filter to collect the crystals and wash them with cold water.
The final steps complete the crystallization process. Filter the cooled solution to separate the crystals from the mother liquor. Wash the crystals with a small amount of cold distilled water to remove impurities. Finally, dry the crystals by pressing between filter papers or placing in a warm oven to obtain pure, dry crystals of hydrated magnesium nitrate.
This diagram shows the complete crystallization process from start to finish. We begin by filtering to remove excess magnesium, then heat to concentrate the solution, cool slowly to form crystals, and finally collect, wash, and dry the crystals. This systematic approach ensures we obtain pure, dry crystals of hydrated magnesium nitrate as the final product.
To summarize the crystallization process: filter to remove excess magnesium, heat to concentrate the solution, cool slowly for crystal formation, then wash and dry to obtain pure crystals. This systematic approach ensures high-quality hydrated magnesium nitrate crystals.