Sources: Dime, Keeleysam, Wikimedia commons, Nickel: Mywood, Wikimedia Commons, Quarter:Dbenbenn, Wikimedia Commons

Let's look at these 9 coins to review percent composition. When you are determining the percent composition of a compound, you have to calculate the compound's molecular mass. The molecular mass of a compound is the total atomic masses of all of the elements in the compound. If the atomic mass of each of these coins is equal to the coin's value, what would be the molecular mass of a compound made from all of the coins? Type your answer in your notes.

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How much money is shown?

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120 cents

Now let's calculate what percent of the dime element makes up the coin compound. Add up the value of the dimes, this represents the atomic mass of all the dimes. What is the atomic mass of the dimes?

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30 cents

To calculate the percent composition, use the following equation.

Percent composition = Fraction: Total atomic mass of one element over Total molecular mass of the compound Total atomic mass of one money element Total amount of money × 100

What is the percent composition of the dime element?

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25%

Now determine the percent composition of the remaining elements in the coin compound. What is the percent composition of the nickel element?

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12.5%

What is the percent composition of the quarter element?

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62.5%

To check your answer, the total of all of the percents should add up to 100%. Due to rounding of decimals, this can vary between 99 – 101% in some cases. Let's check our answers.