EMPIRICAL FORMULAS (II)
1. A reaction requires pure anhydrous calcium sulfate, CaSO4. Only an unidentified hydrate of calcium
sulfate, CaSO4 • (X)H2O is available. A 67.5 g sample of the compound was heated until all the
water had been driven off resulting in a 53.4g mass of pure calcium sulfate. What is the formula and
name of the compound?
2. Find the empirical formula of a compound that contains 53.70% iron and 46.30% sulfiir.
3. Analysis of a compound indicates that it contains 1.04 g K, 0.70 g Cr, and 0.86 g O. Find its
empirical formula.
4. If 11.75 g of hydrated cobalt (II) chloride is heated, 9.25g of anhydrous cobalt chloride remains.
What is the formula and name for this hydrate?
5. A 175.0 g sample of a compound contains 56.15 g C, 9.43gH, 74.81 g O, 13.1 lg N and 21.48 Na.
What is its empirical formula?
6. An oxide of nitrogen is 26% nitrogen by mass. The molar mass of the oxide is app. 105 ghnol. What
is the empirical formula?
J. A hydrate is found to have the following percent composition: 48.8% MgSO4 and 51.2% water. -What is the formula and name of the hydrate.
$_ Ascorbic acid (Vito contains 40.92- percent C, 4.58% H, 54.50% 0 b mass. What is the empirical
formula of ascorbic acid?
9. A 5.325g sample of methyl benzoate, a compound used in the manufacture of perfumes, is found to
contain 3.758g of carbon, 0.316g of hydrogen, and 1.251g of oxygen. What is the empirical formula.
10. Amass of 2.50g of blue, hydrated copper sulfate (CuSO40 XH?O) is placed in a crucible and heated.
After heating, 1.59g white anhydrous copper sulfate rem_ ains..What is the formula and name for the
--hydrate?
11. Although the mineral ilmenite contains more iron than titanium, the ore is usually mined and
processed for titanium, a strong, light, and flexible metal. A sample of ilmenite is found to contain
5.41 g iron, 4.64g .titanium, and 4.65g oxygen. Determine the empirical formula.