Honors Chemistry I
Mole Concept / Molarity / Empirical & Molecular Formulas
Practice Test
Make sure to use the proper number of sig. figs and include the proper units with all answers.
1.______What is the mass, in grams, of a single molecule of hydrosulfuric acid?
2.______A 30.0-liter sample of dinitrogen pentoxide contains how many grams of oxygen?
3.______How many molecules of water are present in 80.0 milligrams of ferric chlorate tetrahydrate?
4.______What is the percentage of metal in a 2.000-gram sample of barium dichromate?
5.______What is the mass of exactly 13.50 liters of carbon monoxide gas at STP conditions?
6.______What is the number of hydrogen atoms in 34.7 grams of phosphoric acid?
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7.______If you had 3.00 moles of auric carbonate, how many moles of pure oxygen gas could you get from this sample? [Hint: remember that oxygen gas is diatomic!]
8.______How many total atoms are in exactly 1.000 milligram of sodium tetraborate?
9.______How many moles of perchloric acid do you need in order to release 10.0 liters of hydrogen gas (H2) at STP?
10.______If a compound of stannic chloride contains 45.53% tin by weight, how many chloride ions are there in 30.0 grams of this compound?
11.______How many ions (total of both cations and anions) are there in 0.0250 moles of chromium(III) oxalate?
12.______How many moles of metal can be recovered from 125 grams of strontium molybdate?
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13.______If 300.0 milliliters of a 6.15 M solution of nitric acid is diluted until the new concentration is only 2.04 M, what will be the final volume of this diluted solution?
14.______What is the empirical formula of a substance that is analyzed and found to contain 38.77% calcium, 19.98% phosphorus, and 41.25% oxygen?
15.______How much water must be added to 45.0 ml of a 2.00 M solution of phosphoric acid to produce a 0.550 M solution of this acid?
16.______4.72 grams of a gas at STP conditions occupies 575 ml. This gas is known to contain 30.435% nitrogen and 69.565% oxygen. What is the true, or molecular formula?
17.______How many grams of barium hydroxide need to be added to 750.0 ml of water in order to produce a 0.0189 M solution of this base?
18.______When 44.466 grams of a hydrate of barium nitrate is heated, 30.000 grams of the anhydrous residue remains. What is the correct formula of this hydrate?
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19.______What is the molarity of a solution if 1.35 grams of lithium chlorite is added to enough water to make 25.0 ml of solution?
20.______How many liters of water must be added to 4.75 liters of a 10.25 M solution of potassium chloride in order to end up with 11.20 liters of a 4.347 M solution?
21.______What is the [S-2] if 2.00 moles of ferric sulfide is added to enough water to produce 800.0 ml of solution?
22.______Oxygen gas is passed over a 5.000-gram sample of solid manganese and allow to react with this metal. If 7.186 grams of an oxide form of manganese is produced, what is the empirical formula of this compound?
23.______An organic compound is known to contain 48.00 grams of carbon, 3.25 x 1024 atoms of hydrogen, and 1.20 moles of oxygen atoms. If 4.000 grams of this compound is known to be 0.01102 moles, what its true molecular formula?