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Unformatted text preview: nanni (arn437) Mastering Molecular Weights - problems and video CNS (87654) 1 This print-out should have 3 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. 001 10.0 points The molecular formula for strontium oxide is SrO. A chemist decomposes strontium car- bonate to make 24.7 grams of strontium oxide. How many moles of SrO are made? Correct answer: 0 . 24 moles. Explanation: Find the molecular weight of SrO, and then divide the mass of SrO by the molecular weight to find the number of moles. MW SrO = MW Sr + MW O = 87 . 62 g / mol + 15 . 999 g / mol = 103 . 619 g / mol Thus, the number of moles is moles = 24 . 7g parenleftbigg 1mol MW SrO parenrightbigg = 24 . 7g parenleftbigg 1mol 103 . 619g parenrightbigg = 0 . 238373 mol = 0 . 24 moles 002 10.0 points Chlorine is a toxic gas that irritates the respi- ratory system. How many moles of chlorine is there in 11.5 grams?...
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- Fall '07