Chem I
Name _________________________ Date _______________ Per ________ Review For The Test: Percent Composition, Formulas, and Hydrates (Show all your set-ups and be meticulous regarding units and sig figs.)
1. Don’t Forget! What’s the formula for each of these ions? ________________ acetate
________________ sulfate
________________ phosphate
________________ chlorate
________________ nitride
________________ permanganate
________________ nitrate
________________ hypochromite
________________ nitrite
________________ dichromate
________________ carbonate
________________ hydroxide
________________ chromate
________________ sulfite
________________ cyanide
________________ peroxide
________________ ammonium
________________ perchlorate
2. What do the L, the D, and the 50 mean in LD50? L = ____________________ D = _____________________ 50 = _________ Which is more poisonous: something with a high LD50 or something with a low LD50? ________ 3. What’s the percent composition of each of these? a. lithium chloride: Li = ________________ Cl = ________________ b. calcium hydroxide: Ca = _______________ O = ________________ H = ________________ c. iron (III) persulfate: Fe = _______________ S = ________________ O = ________________
4. If the empirical formula of a compound is SO2 and its molecular mass is 512 grams per mole, what is the compound’s molecular formula?
____________________ 5. If a compound that has a molecular mass of 118.10 g/mol and is 40.6% carbon, 5.1% hydrogen, and 54.3% oxygen, a. what is its empirical formula? _____________________ b. what is its molecular formula? ____________________ (show your set-ups below)
6. What is the molecular formula of a compound that has 4.433 g phosphorus, 5.717 g oxygen, and has a molecular mass of 568 grams/mole? (show your set-ups below) ____________________
7. A hydrate of iron II sulfate is found to be 54.63% FeSO4 and 45.37% water. What is the formula of the hydrate?
What would be the name of this hydrate? __________________________________________ 8. A 393.7 gram sample of a hydrate of tin IV chloride is heated to drive off the water. The remaining anhydrous (water free) powder has a mass of 253.5 grams. What is the formula of the hydrate?
What would be the name of this hydrate? __________________________________________ 9. How many grams of water would there be in 956 grams of LiClO•2H2O?
10. Finally, a lab type question. Let’s say you need to know the formula for chromium chloride but all you have is granular chromium and hydrochloric acid. So you do a lab just like the zinc chloride lab we did and you get the following results: mass (in grams) empty beaker
48.69 grams
granular chromium
1.59 grams
beaker + chromium chloride
54.61 grams
What is the formula of the chromium chloride made in this lab? (Show all your set-ups.)
11. What if this had been the results of the lab from the previous problem? mass (in grams) empty beaker
35.67 grams
granular chromium
1.27 grams
beaker + chromium chloride
42.99 grams
What is the formula of the chromium chloride made in this lab? (Again, show all your set-ups.)
