How many moles are in 8 5 mL of acetic anhydride density of 1 082? use the molec

Question

How many moles are in 8 5 mL of acetic anhydride density of 1 082? use the molecular weights that you have already calculated Give two significant figures What is the molecular formula (Hill method) of phosphoric acid? Use the appropriate capitalization of your atomic symbols Given the following atomic weights what is the molecular weight of phosphoric acid? Give no decimals or extraneous marks C = 12, H = 1, N = 14, 0 = 16, P = 31 As a "rule of thumb" there are 20 drops of a liquid in a mL. Using this estimate and a density of 1 685 how many moles are in 58 drops of 85 % by weight phosphoric acid? Use the molecular weights that you already calculated Give two significant digits and no extraneous marks What is the molecular formula (Hill method) of Acetylsalicylic acid? Use appropriate capitalization of your atomic symbols.

Explanation / Answer

1) Density = Mass/Volume

Mass = Volume * Density = 8.5 mL * 1.082 g/mL = 9.197 grams

Molar mass of acetic anhydride (C4H6O3) = 4 * 12 + 6 * 1 + 3 * 16 = 102 gm/mol

Number of moles = Mass/molar mass = 9.197/102 = 0.09016 moles

2) Formula of Phosphoric acid = H3PO4

3) Molar mass of Phosphoric acid (H3PO4) = 3 * 1 + 31 + 4 * 16

=> 3 + 31 + 64

=> 98 gm/mol

4) Volume of solution = 58 drops * 1mL/20 drops = 2.9 mL

mass of Phosphoric acid = 2.9 mL * 85/100 (Percent by weight) * 1.685 g/mL

=> 4.153 grams

Number of moles of Phosphoric acid = 4.153/98 = 0.04238 moles

5) Formula of acetyl salicylic acid or aspirin is C9H8O4

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