Question

1. find the percent composition of each compound as given:

a. % o in feo
b. % cl in mgcl₂
c. % c in ch₄
d. % s in caso₄
e. % cl in hcl

1. a compound consisting of aluminum and chlorine weighs 17.82 grams. the aluminum in the compound weighs 3.70 grams.

a. what is the weight of the chlorine in the compound?
b. what is the experimental % al in the compound?
c. if the formula is alcl₃, what is the expected % al?
d. what is the percent error?
|expected - experimental| / expected x 100

Explanation:

1. a. % O in FeO

Step1: Find molar mass of O and FeO

Molar mass of O ($M_O$) = 16 g/mol.
Molar mass of FeO ($M_{FeO}$): Fe has molar mass $M_{Fe}=55.85$ g/mol, so $M_{FeO}=55.85 + 16=71.85$ g/mol.

Step2: Calculate mass percent

Mass percent of O = $\frac{M_O}{M_{FeO}}\times100\%=\frac{16}{71.85}\times 100\%\approx22.3\%$

1. b. % Cl in $MgCl_2$

Step1: Find molar mass of Cl and $MgCl_2$

Molar mass of Cl ($M_{Cl}$) = 35.45 g/mol. There are 2 Cl atoms.
Molar mass of $MgCl_2$ ($M_{MgCl_2}$): Mg has molar mass $M_{Mg} = 24.31$ g/mol, so $M_{MgCl_2}=24.31+(2\times35.45)=24.31 + 70.9=95.21$ g/mol.

Step2: Calculate mass percent

Mass percent of Cl = $\frac{2\times M_{Cl}}{M_{MgCl_2}}\times100\%=\frac{70.9}{95.21}\times 100\%\approx74.5\%$

1. c. % C in $CH_4$

Step1: Find molar mass of C and $CH_4$

Molar mass of C ($M_C$) = 12.01 g/mol.
Molar mass of $CH_4$ ($M_{CH_4}$): H has molar mass $M_H = 1.01$ g/mol, so $M_{CH_4}=12.01+(4\times1.01)=12.01 + 4.04=16.05$ g/mol.

Step2: Calculate mass percent

Mass percent of C = $\frac{M_C}{M_{CH_4}}\times100\%=\frac{12.01}{16.05}\times 100\%\approx74.8\%$

1. d. % S in $CaSO_4$

Answer:

1. a. Approximately $22.3\%$
2. b. Approximately $74.5\%$
3. c. Approximately $74.8\%$
4. d. Approximately $23.6\%$
5. e. Approximately $97.2\%$
6. a. $14.12$ g
7. b. Approximately $20.8\%$
8. c. Approximately $20.2\%$
9. d. Approximately $3.0\%$