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Percent composition is a helpful concept in chemistry for understanding how much of each element is present in a compound. It tells us the percentage of the total mass that is made up by a particular element. For instance, when we talk about cisplatin having 65% platinum, we're saying that in any sample of cisplatin, 65% of its weight is due to platinum. This concept is crucial because it helps to easily compare and use substances in chemical reactions.
To use percent composition effectively, there’s a basic conversion we always use: converting the percentage into a decimal form. This is done by dividing the percentage by 100. This step enables us to use the percentage directly in calculations, such as when multiplying it by the mass of a compound to find out how much of a specific element is present.

Mass calculation is straightforward once you've understood the concept of percent composition and how to convert a percentage into a decimal. To find out the mass of a specific element in a compound, you simply multiply the total mass of the compound by the decimal form of the percentage of that element.
For example, if you have 1.53 grams of cisplatin, knowing that cisplatin is 65% platinum means converting 65% to 0.65 and then multiplying by 1.53 grams. This math will give you the mass of platinum within that amount of compound. Specifically, the calculation would be:

• Convert the percent into a decimal: 65% → 0.65
• Multiply by the sample's mass: 1.53 g × 0.65 = 0.9945 g

Thus, in 1.53 grams of cisplatin, about 0.9945 grams is platinum.

Platinum is a dense and precious metal, often used in a variety of applications, including jewelry and industrial uses. It is also an important element in medicine. Cisplatin, a platinum-containing drug, is used to treat cancer by interfering with the DNA in cancer cells and stopping them from growing or dividing.
Understanding how much platinum is present in a sample of cisplatin is important for dosing the drug effectively, as well as for cost calculations. The percent composition tells us that 65% of the compound's mass is platinum, and it is crucial for chemists and pharmacologists to know this so they can balance efficacy and safety in treatment. By calculating the mass of platinum using the compound’s total mass and its percent composition, healthcare professionals can ensure the right amount of the active ingredient is being administered.