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Design a practical investigation into the formula of a metal oxide.

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Design a practical investigation into the formula of a metal oxide. Aim: to determine the formula of magnesium oxide. Hypothesis: I think that the formula for the metal oxide magnesium oxide, will be MgO. Variables Independent: the mass of magnesium is manipulated as different sizes are cut from the roll of magnesium. The mass is the variable that is altered. Dependant: the mass of magnesium oxide formed will be the measured variable as it enables us to determine the formula for magnesium oxide. Controlled Each strip of magnesium was taken from the same roll. If magnesium ribbons were taken from various rolls, the reaction with oxygen and the formation of magnesium oxide would be affected. The same roll ensured that all the magnesium used was the same. The magnesium was scraped with sand paper. This was to remove any oxygen that may have formed onto it. Any oxygen on the magnesium would have altered the results. ...read more.


Mass of crucible + lid 31.15g Mass of crucible + lid + magnesium 31.23g Mass of crucible + lid + magnesium oxide 31.27g Observation After heating the magnesium strongly for few minutes it began to melt and glowed with a bright light. Lifting the lid caused the magnesium to glow even more brightly and white smoke escaped from the crucible. Magnesium turned to a grayish - white powder and no longer glowed with a bright light. Mass of magnesium = 31.23 - 31.15 = 0.08g Mass of magnesium oxide = 31.27 - 31.15 = 0.12g Mass of oxygen combined with magnesium = 0.12 - 0.08 = 0.04g Analysis Empirical formula Magnesium Oxygen Amount 0.08g 0.04g Moles 0.08 / 24.31 = 0.0033 0.04 / 16.00 = 0.0025 Ratio 0.0033 / 0.0025 = 1.32 0.0025 / 0.0025 = 1 1 1 Empirical formula is MgO. Error analysis Percent age uncertainty = error in balance *100 Mass of substance = 0.01/ 0.08 *100 =12.5% Conclusion and evaluation The formula for the metal oxide, magnesium oxide was MgO. ...read more.


the high temperatures may have caused the crucible to react. This would have affected the products formed. Lifting the lid may have lead to some of the products escaping and the product weighing less, therefore the ratio of magnesium to oxygen would be incorrect. Weighing the magnesium oxide while it was still hot would have caused an error as the products would have expanded and they would be heavier than they actually are. Other factors contributed to the precision of the results obtained. Scraping the magnesium ensured that pure magnesium was used and no other products were formed. Repetition of the experiment enabled a more accurate result to be achieved. Improvements The magnesium should be burnt in pure oxygen. This would reduce the formation of products other than magnesium oxide and would give more accurate results. A stronger crucible should be used so that it doesn't react during the high temperatures reached when the experiment is going on. Pure magnesium should be used to prevent the formation of products other than magnesium. ?? ?? ?? ?? ...read more.

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