What is the percent composition of Ca(C2H3O2)2? Select one:
a. 25.3% Ca, 30.4% C, 3.8% H, 40.5% O
b. 40.4% Ca, 24.2% C, 3.1% H, 32.3% O
c. 6.67% Ca, 26.67% C, 40.0% H, 26.67% O
d. 12.5% Ca, 25% C, 37.5% H, 25% O

Choice a. The compound contains approximately , by mass, approximately by mass, approximately by mass, and approximately by mass.

Explanation:

Look up the relative atomic mass of these elements on a modern periodic table:

The relative atomic mass of an element gives the numerical value of the mass (in grams) of one mole of the atoms of this element. For example, the relative atomic mass of hydrogen is . Therefore, the mass of one mole of hydrogen atoms would be (approximately) .

One mole of formula units include:

Inside each mole of ions, there are:

Therefore, that of ions in one mole of formula units would include:

In summary, each mole of formula units would contain:

Calculate the mass of these atoms using their relative atomic mass data.

For example, the mass of one mole of atoms is (approximately) because the relative atomic mass of hydrogen is . Therefore, the mass of that of hydrogen atoms would be approximately:

.

Similarly, calculate the mass of the other three elements in one mole of formula units:

The sum of these masses is .

In other words, the mass of one mole of formula units is (approximately) . Approximately of that is . Therefore, the percentage of by mass in would be approximately:

.

In other words, accounts for approximately of the mass of .

In a similar way, calculate the percentage of the other three elements by mass.

answer: a chemical reaction

explanation:

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air

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then a couple days later you check the air pressure in the tire

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