I need help with Chemistry homework! Its about limiting reagents and percent yield

Posted on 2014-03-25 08:26:00 in Chemistry by LINDY FIKE

1. Which element is in excess when 3.00 g of Mg is ignited in 2.20 g of pure oxygen? What mass is in excess? What mass of MgO is formed?



2. How many grams of Al2S3 are formed when 5.00 grams of Al is heated with 10.0 grams S?



3. Solid calcium carbonate, CaCO3, is able to remove sulphur dioxide from waste gases by the reaction: CaCO3 + SO2 + other reactants ----> CaSO3 + other products



In a particular experiment, 225 g of CaCO3 was exposed to 135 g of SO2 in the presence of an excess amount of the other chemicals required for the reaction?

a) What is the theoretical yield of CaSO3?

b) if only 198 g of CaSO3 was isolated from the products, what was the percentage yield of CASO3 in this experiment?



4. Certain salts of benzoic acid have been used as food additives for decades. The potassium salt of benzoic acid, potassium benzoate, can be made by the action of potassium permanganate on toluene.

C7H8 + 2KMnO4 ------> KC7H5O2 + 2MnO2 + KOH + H2O

Toluene- Potassium- Benzoate-



I need to show my work, thanks so much!

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