Percent Composition and Empirical Formulas Flashcard

Front

What is percent composition?

Back

Percent composition is the percentage by mass of each element in a compound.

Front

How do you calculate the percent by mass of an element in a compound?

Back

Percent by mass = (mass of element in 1 mole of compound / molar mass of compound) x 100%.

Front

What is the empirical formula?

Back

The empirical formula is the simplest whole-number ratio of moles of elements in a compound.

Front

How do you determine the empirical formula from percent composition?

Back

Convert the percent composition to grams, then to moles, and find the simplest ratio.

Front

What is the empirical formula of C3H6?

Back

CH2.

Front

Which pair has the same empirical formula: NaCrO4 and Na2Cr2O7 or C2H4O2 and C6H12O6?

Back

C2H4O2 and C6H12O6.

Front

What is the percent by mass of sodium in NaCl?

Back

39%.

Front

If a compound has 88.80% copper and 11.20% oxygen, what is its empirical formula?

Back

Cu2O.

Front

What does it mean if two compounds have the same empirical formula?

Back

They have the same simplest ratio of elements, but may differ in molecular structure or mass.

Front

What is the molar mass of NaCl?

Back

The molar mass of NaCl is approximately 58.44 g/mol.