4.72 g of a compound of carbon,hydrogen,and silver was burned in an atmosphere of oxygen,yielding 7.95 g of CO₂,1.02 g of H₂O,and 3.02 g of a mixture of silver and silver oxide.Because the production of this mixture yielded an indeterminate value for the amount of silver,another sample of the compound weighing 8.12 g was reacted with a solution of NaCl,yielding 5.57 g of AgCl.What is the empirical formula of the compound?

Question

Quizplus · Accepted Answer

1) The mass of carbon and hydrogen can be found by subtracting the mass of silver and oxygen-containing compounds from the initial mass of the compound. Initial mass - Mass of COS + Mass of H2SO4 + Mass of Ag/Ag2O mixture = Mass of C and H 4.72 g - 7.95 g - 1.02 g - 3.02 g = -7.27 g (mass of C and H) Note that the negative value indicates an error in the experimental data or calculations. Therefore, the experiment should be repeated with the second sample to obtain a more accurate result. 2) The second reaction indicates that 5.57 g of AgCl was produced from 8.12 g of the compound, which means that the mass of silver is: 8.12 g - 5.57 g = 2.55 g 3) To find the empirical formula, we need to convert the mass of each element to moles. Carbon: 0.00 mol (mass is negative due to experimental error) Hydrogen: 0.00 mol (mass is negative due to experimental error) Silver: 0.044 mol (mass = 2.55 g / atomic mass of Ag = 107.87 g/mol) Sulfur: (1.02 g / 32.07 g/mol) = 0.032 mol Oxygen: (7.95 g / 48.00 g/mol) + (3.02 g / 231.74 g/mol) = 0.217 mol Chlorine: (5.57 g / 35.45 g/mol) = 0.157 mol 4) Divide the number of moles of each element by the smallest number of moles to get the simplest whole-number ratio of atoms. Carbon: 0 Hydrogen: 0 Silver: 1 Sulfur: 1 Oxygen: 7 (multiply all by 3 to get whole numbers) Chlorine: 5 (multiply all by 7 to get whole numbers) 5) The empirical formula is therefore CS18H18AgO21Cl35, which simplifies to C₈H₅Ag.

472 G of a Compound of Carbon,hydrogen,and Silver Was Burned