Molar Mass, Conversions, Percent Composition Empirical Formula

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					Molar Mass, Conversions, Percent Composition &
Empirical Formula
For each of the following write the correct formula, then find the molar mass in grams.

                                     Formula                       Molar Mass

1. Ammonium Dichromate __________________                   _____________________

2. Iron (III) Sulfate         __________________            _____________________

3. Silicon Tetrachloride      __________________            _____________________

4. Phosphorus Pentoxide       __________________            _____________________

5. Lead (IV) Acetate          __________________            _____________________

Use Dimensional analysis for each of the following. Place your final answer, with proper units, in the blank
provided.

1. How many grams of sodium hydroxide are needed to unclog a stopped up toilet that requires 7.98 x 1025
molecules of sodium hydroxide?


                                                                                                 ____________
2. How many grams of potassium chlorate are available in 0.0005 moles of potassium chlorate?



                                                                                             ____________
3. If you pour 44.8 moles of hydrogen peroxide onto a cut on your knee, how many molecules have you
poured?


                                                                                                 ____________
4. How many moles of zinc chromate are present in 67.5 grams of zinc chromate?



                                                                                            ____________
5. How many molecules of sodium bicarbonate (aka baking soda) are used to brush your teeth when 8.3 grams
are spread onto the toothbrush?


                                                                                                 ____________
6. Given 2.0 moles of hydrogen hydroxide, how many grams are present?



                                                                                                 ____________
Percent Composition
Determine the percentage composition of each of the compounds below.

1. KMnO4              K = _____________             Mn = _______________                   O = ______________

2. HCl                H = _____________             Cl = ________________

3. Mg(NO3)2           Mg = _____________            N = ________________                   O = ______________

4. (NH4)3PO4          N = ____________      H = ____________       P = ____________        O = ______________

5. Al2(SO4)3          Al = ____________             S = ________________                   O = ______________

Empirical Formula & Molecular Formula
Determine the empirical formula and/or molecular formula for each of the following.

1a) A compound is found to contain 63.52% iron and 36.48% sulfur. Find its empirical formula. 1a__________




1b) If the molar mass of the molecular formula is 87.9 g, what is the molecular formula?         1b__________



2a) Find the empirical formula of a compound found to contain 26.56% potassium, 35.41% chromium, and the
remainder oxygen.
                                                                                            2a__________




2b) If the molar mass of the molecular formula is 294.2g, what is the molecular formula?         2b__________



3) Analysis of 20.0 g of a compound containing only calcium and bromine indicates that 4.00 g of calcium are
present. What is the empirical formula of the compound formed?