Chemistry Percent Composition

What is the general formula for the computation of percentage composition of the given element?

• % mass of element = mass of element in the compound divided by mass of the compound times 100

• % mass of element = mass of element in the compound divided by mass of the compound

• % mass of element = mass of element in the compound divided by 100

• % mass of element = mass of element in the compound

What is the percent by mass of chlorine in NaCl?

• 39%

• 61%

• 35%

• 35%

What is the percent by mass of fluorine in CaF₂ (gram-formula mass = 78 g/mol)?

• 24%

• 49%

• 49%

• 65%

What is the percent by mass of calcium in CaF₂ (gram-formula mass = 78 g/mol)?

• 24%

• 49%

• 51%

• 65%

Complete the formula for % Composition.

a

b

c

100

total mass of compound

mass of element

What is the equation for calculating percent composition?

• mass of element/mass of compound = x 100

• mass of compound/mass of element = x 100 

• total mass/molar mass = x 100 

• molar mass/molar mass = x 100 

The percent, by weight, of carbon in C₄H₈O₃ is (a)   .

• 55%

• 72%

• 31%

• 46%

(Page 38-40) Percent Composition is the ​ (a)   by ​ (b)   of each element in a compound.

• percentage

• mass

• compound

Find the percent composition of Aspirin C9H8O4?

• 180 g/mol

• O

• 60%

• Molar Mass of C9

• 35.6%

• Molar Mass of Aspirin

• 4.4%

• C

• 108 g/mol

• H

Find the percent composition of Cu₂S?

• %Cu= 67.987 %S= 32.013

• %Cu= 79.854 %S= 20.145

• %Cu= 35.946 %S= 64.054