Chemical Quantities: Empirical Formula

If a compound has an empirical formula of NH2 and a molar mass of 32 g/mol, what is the molecular formula?

• NH2

• N2H4

• NH3

• N3H6

The empirical formula of a compound is the same as its molecular formula when ____.

• The compound is ionic

• The compound is a gas

• The molar mass is a multiple of the empirical formula mass

• The molar mass equals the empirical formula mass.

What is the empirical formula? A) The simplest whole-number ratio of atoms in a compound B) The actual number of atoms in a molecule C) The molecular weight of a compound D) The percent composition of a compound.

• The simplest whole-number ratio of atoms in a compound

• The actual number of atoms in a molecule

• The molecular weight of a compound

• The percent composition of a compound.

Given the percent composition of a compound, which of the following steps is NOT necessary to calculate the empirical formula?

• A) Convert the percentage to grams

• B) Convert grams to moles

• C) Divide by the smallest number of moles

• D) Multiply by Avogadro's number.

If a compound is composed of 40% carbon, 6.7% hydrogen, and 53.3% oxygen, what is its empirical formula?

• CH2O

• C2H4O2

• C3H6O3

• CHO

Fill in the blank: The empirical formula is important for understanding the _______ of a compound.

• A) basic structure

• B) molecular weight

• C) density

• D) boiling point

Fill in the blank: The second step in the chemistry poem is 'Mass to ______'.

• Percent

• Moles

• Whole

• Small

Tags

NGSS.HS-PS1-7

What is the third step in the chemistry poem?

• Multiply by whole

• Percent to mass

• Divide by small

• Mass to moles

Fill in the blank: The poem suggests to 'Divide by ______' as one of the steps.

• Large

• Whole

• Small

• Percent

Which step comes after 'Mass to moles' in the poem?

• Percent to mass

• Divide by small

• Multiply by whole

• Add by large