Question

use the periodic table to calculate the gfw (molar mass) of aluminum sulfate, al₂(so₄)₃ to 5 significant figures. use the values provided here: al = 26.981 s = 32.065 o = 15.999 remember that the atomic weights on the periodic are not given units. as an average, a single atom of al has a mass of 26.981 amu. one mole of al atoms has a mass of 26.981 g, or 26.981 g/mol. a chemical formula is the ratio of moles of each element. for example, in h₂o there are 2 moles of h and 1 mole of o. al (1mol)(26.981 g/mol) = 2 g s (3mol)(32.065 g/mol) = 4 g o (5mol)(15.999 g/mol) = 6 g 7 g/mol a. 1 b. 2 c. 3 d. 4 e. 5 f. 6 g. 7 h. 8 i. 9 j. 10 k. 12 l. 75.045 m. 150.09 n. 225.135 o. 342.15 p. 26.981 q. 32.065 r. 15.999 s. 53.962 t. 96.195 u. 191.988

Explanation:

Step1: Calculate mass of Al

In \(Al_2(SO_4)_3\), there are 2 moles of Al.
\(2\times26.981 = 53.962\) g

Step2: Calculate mass of S

In \(Al_2(SO_4)_3\), there are 3 moles of S.
\(3\times32.065=96.195\) g

Step3: Calculate mass of O

In \(Al_2(SO_4)_3\), there are \(4\times3 = 12\) moles of O.
\(12\times15.999 = 191.988\) g

Step4: Calculate molar mass of \(Al_2(SO_4)_3\)

Sum up the masses of Al, S and O.
\(53.962+96.195 + 191.988=342.145\approx342.15\) g/mol

Answer:

1. B. 2
2. S. 53.962
3. C. 3
4. T. 96.195
5. K. 12
6. U. 191.988
7. O. 342.15