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In 1799, French chemist Joseph Proust proposed Law of Definite Proportion. It states that the proportion by mass of the elements in a given compound is always the same (i.e. fixed mass ratio). In "Dimensional Analysis" land, the law of definite proportion is a conversion factor between the mass of elements (or with the total mass) of a compound. Therefore, once you have this fixed mass ratio, you can use dimensional analysis to calculate unknown mass information.
Show all work using the dimensional analysis process and appropriate math/sig fig.
1. A sample of the compound methane (CH4) consists of 75g carbon and 25g of hydrogen. How many grams of carbon are in a sample if there are 24.5g of hydrogen?
2. In a 456g sample of a compound, there are 129g of boron. What is the mass of the compound if there are 546g of boron?
3. A 125g sample of a compound (that consists of Na & S) has 24.41g of Na. If you have 45.2g of the compound, how many grams of S do you have?
Answers: