Chemistry Chapter 10.3

______________ is the percent by mass of each element in the compound.

• percent molarity

• avogadro's number

• mass percentage

• percent composition

Which of the equations is used to find the percent composition from mass?

The _______ of a compound gives the lowest whole-number ratio of the atoms or moles of the elements in a compound.

• molar formula

• molecular formual

• empirical formula

• atomic formual

When calculating percent composition from a formula, which of the following correctly finds the mass of carbon in C₂H₄?

• 2 mol x 12 g/mol = 24 g

• 4 mol x 12 g/mol = 48 g

• 2 mol x 1 mol/12 g= 24 g

• 4 mol x 1 mol/12 g= 48 g

What is the equation for finding the percent composition from the empirical formula?

Reorder the following steps: Finding the molecular formula of a compound.

• calculate the empirical formula mass

• divide the molar mass by the empirical formula mass

• multiply the formula subscripts by the value obtained

Reorder the following: Determining the empirical formuala of a compound

• divide each molar quantity by the smaller number of moles to get 1 mol for the element with the smaller number of moles

• convert the percent by mass of each element to moles

• multiply each part of the ratio by the smallest whole number that will convert both subscripts to whole numbers

What is the percent composition of Mg in Mg(OH)₂? Show your work!

What do you use as a conversion factor when calculating grams from moles or moles from grams?

• the molar mass

• the subscript

• the moles of the element

• the grams given

A compound is formed when 10.03 g Mg combines with 4.48 g of N. What is the percent composition of N?