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Q: Chemistry Problem ( No Answer,   1 Comment )
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 Subject: Chemistry Problem Category: Science > Chemistry Asked by: dana3-ga List Price: \$15.00 Posted: 25 Jul 2006 06:02 PDT Expires: 24 Aug 2006 06:02 PDT Question ID: 749298
 ```I am trying to complete this chemistry class and need some help with some of my problems. The question is listed below, any help you can give me is greatly appreciated and can you direct me to a website where I can get some additional help with Freshman Chemistry. "Pure oxygen gas can be prepared in the laboratory by the decomposition of solid potassium chlorate to form solid potassium chloride and oxygen gas. How much oxygen gas in grams can be prepared from 45.8 g of potassium chlorate?" Thank you.```
 ```First you need to write a balanced chemical equation: 2KClO3 ----- 2KCl + 3 O2 Now if you have 45.8g of KClO3.. How many moles of KClO3 do you have? The molar mass of KClO3 is 122.55 g/mol. Therefore there are 45.8g/122.55g = 0.37372501 moles. Now use molar ratios to find the moles of O2: 0.373 mol/2 = xmols / 3 x mols = 0.560587515 moles of O2. Now to find the mass of the O2 produced use the molar mass of oxygen to multiply it by the number of moles: 0.560587515 mol x 15.9994 g/mol = 8.97 g of O2 are produced. Notice there are 3 significant digits in the question, so the final answer also has 3 significant digits. Hopefully that helps!! Brian```