Ch. 10.3 - Percent Composition and Chemical Formulas

Ch. 10.3

Percent Composition and Chemical Formulas

Multiple Choice

When a 14.2 g sample of mercury (II) oxide is decomposed into its elements by heating, 13.2 g Hg is obtained. What is the percent composition of the compound?

• 63.0% Hg, 37.0% O

• 50% Hg, 50% O

• 93.0% Hg, 7.0% O

• 28% Hg, 72% O

Multiple Choice

A sample of a compound analyzed in a chemistry laboratory consists of 5.34 g of carbon, 0.42 g of hydrogen, and 47.08 g of chlorine. What is the percent composition of this compound?

• 10.1% C, 0.795% H, 89.1% Cl

• 18.3% C, 6.4% H ,75.3% Cl

• 7.4% C, 2.1% H ,90.5% Cl

• 11.4% C, 0.6% H ,87.7% Cl,

Fill in the Blank

Calculate the percent nitrogen in NH₃.

(round to the nearest whole number)

= ____________ % N

Fill in the Blank

Calculate the percent nitrogen in NH₄NO₃.

(round to the nearest whole number)

= ____________ % N

Fill in the Blank

From the formula for calcium acetate, Ca(C₂H₃O₂)₂, calculate the mass of carbon that can be obtained from 65.3 g of the compound.

(round to 3 sig figs)

= _____________ g C