MediumChemistryHigh School (11–12)Atoms and Molecules › Laws of Chemical CombinationAtoms and Molecules › The Mole ConceptNumericalpythonBoard Exam
Sulfur forms two oxides. Oxide A is 50.0% sulfur by mass, and oxide B is 40.0% sulfur…
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Sulfur forms two oxides. Oxide A is sulfur by mass, and oxide B is sulfur. Find the mass of oxygen that combines with g of sulfur in each. Show that the oxides obey the law of multiple proportions.
Need a reminder? The key ideaShow
Conservation of mass: in a reaction the total mass of the products equals the total mass of the reactants. Definite proportions: a compound always has the same elements in the same proportion by mass. Multiple proportions: when two elements form several compounds, the masses of one that combine with a fixed mass of the other are in a small whole-number ratio. Gay Lussac: reacting gases have volumes in a small whole-number ratio, at the same temperature and pressure.
The worked solution
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Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. Oxide A. g holds g of sulfur and g of oxygen: g of oxygen for each gram of sulfur.
Step 2. Oxide B. g holds g of sulfur and g of oxygen: g of oxygen for each gram of sulfur.
Step 3. Compare. . The masses of oxygen are in the ratio , a ratio of small whole numbers.
Answer: g and g of oxygen, in the ratio , so the law holds. (They are and .)
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