Percentage Composition, Empirical and Molecular Formulae
Ideal Gas Law
Solutions
100
How many atoms are in 0.652 mol of iron?
3.93E23 atoms of Fe
100
Oxygen gas can be produced by decomposing potassium chlorate using the reaction below. If 138.6 g of KClO3 is heated and decomposes completely, what mass of oxygen gas is produced?
KClO3 (s) --> KCl (s) + O2 (g)
54.286 g of O2 are produced
100
Find the percentage composition of KMnO4
24.75% K 34.77% Mn 40.48% O
100
How many liters does 3.8 moles of O2 occupy at STP (standard temperature and pressure)?
STP = 1 atm and 0 °C
85.12 liters
100
Seawater contains roughly 28.0 g of NaCl per liter. What is the molarity of sodium chloride in seawater?
0.479 M
200
How many atoms are in 6.5 moles of iron (III) sulfate?
6.65431E25 atoms
200
4NH3(g) + 6NO(g)→5N2(g) + 6H2O(g)
How many moles of each reactant were there if 13.7 moles of N2(g) is produced?
10.96 moles of NH3
16.44 moles of NO
200
Find the percentage composition of Mg3(PO4)2.
27.75% Mg 23.57% P 48.68% O
200
How many grams of carbon dioxide are there in a container with a volume of 4.50L at STP?
8.83 g of CO2
200
A solution is prepared by dissolving 90 milliliters of pure hydrogen peroxide in enough water to make 3000 milliliters of solution. What is the concentration (in percent of volume) of the hydrogen peroxide solution? What is the concentration of the solution in ppm?
3% = 30000 ppm
300
A sample contains 27.1 g of calcium oxide. How many moles of calcium oxide are in the sample?
0.483 moles of CaO
300
Consider the reaction below. How many grams of aluminum sulfate are produced if 23.33 g Al reacts with 74.44 g CuSO4?
Al (s) + CuSO4 (aq) ----> Al2(SO4)3 (aq) + Cu (s)
53.23 g of Al2(SO4)3 are produced
300
Find the empirical formula of a compound whose percentage composition is as follows:
42.11% C 6.49% H 51.40% O
C12H22O11
300
At what temperature will 0.654 moles of neon gas occupy 12.30 liters at 1.95 atmospheres?
447 K
300
A solution of NaCl has a molarity of 0.549 M. How many moles are in 350 mL of this solution?
0.192 moles of NaCl
400
Consider the following reaction:
N2 + 3H2 ---> 2NH3
How many moles of molecular hydrogen are needed to produce 174.58 moles of ammonia?
261.87 moles of H2
400
Identify the limiting reagent for the given combination of reactants. Calculate the mass of whatever substance will be in excess and how many grams of HF will be made, if there are 5.33 moles of fluorine and 2.22 moles of ammonia.
F2 (g) + NH3 (g) --> N2F4 (g) + HF (g)
Limiting reactant: F2
1.496 g of NH3 in excess
127.92 g of HF produced
400
A compound has a percentage composition of 40.01% C, 6.69 % H, and 53.30% O. Its molar mass is 179.9 g/mol. What is its empirical formula? What is its molecular formula?
96.0 g. of a gas occupies 48.0 L at 700.0 mm Hg and 20.0 °C. What is its molar mass?
52.2 g/mol
400
How many grams of sodium hydroxide are needed to make 250 mL of a 0.200 N solution?
2 g of NaOH
500
How many atoms of P are in 41.2 g of magnessium phosphate?
1.89E23 atoms of P
500
What is the percent yield of the following reaction if 60 grams of CaCO3 is heated to give 15 grams of CaO?
CaCO3 → CaO + CO2
44.6%
500
NutraSweet is 57.14% C, 6.16% H, 9.52% N, and 27.18% O. Calculate the empirical formula of NutraSweet and find the molecular formula. (The molar mass of NutraSweet is 294.30 g/mol)
Empirical formula AND Molecular formula:
C14H18N2O5
500
5.6 g of solid CO2 is put in an empty sealed 0.004 m3 container at a temperature of 300 K. When all the solid CO2 becomes gas, what will be the pressure in the container?
0.7831 atm
500
What mass (in grams) of H2SO4 would be needed to make 750.0 mL of 4.00 N solution?