The U.S. recommended daily allowance (RDA) of folic acid,C 19 H 19 N 7 O 6 is 40

Question

The U.S. recommended daily allowance (RDA) of folic acid,C19H19N7O6 is 400.0micrograms. Calculate the number of molecules in the U.S. RDA??
------------------------------------------------- The ternary compounds called chlorofluorocarbons, or Freons,have proved to be very valuable as refrigerants and as cleaningagents for circuit boards. Unfortunately, in the atmosphere thesecompounds produce chlorine atoms that catalyze the decomposition ofthe ozone that protects the earth from ultraviolet radiation. Oneof these compounds has the following mass percentages: 58.6%Cl and9.93%C.
What is the empirical formula of this compound? --------------------------------------------- A sample of an unknown biochemical compound is found to have apercent composition of 57.14% carbon, 6.17% hydrogen, 9.52%nitrogen and the balance oxygen. What is the empirical formula forthis compound ? --------------------------------- A compound is known to contain 40.45% carbon and 35.90% oxygenby mass. Each molecule contains two atoms of oxygen. What is themolar mass of this substance?
The U.S. recommended daily allowance (RDA) of folic acid,C19H19N7O6 is 400.0micrograms. Calculate the number of molecules in the U.S. RDA??
------------------------------------------------- The ternary compounds called chlorofluorocarbons, or Freons,have proved to be very valuable as refrigerants and as cleaningagents for circuit boards. Unfortunately, in the atmosphere thesecompounds produce chlorine atoms that catalyze the decomposition ofthe ozone that protects the earth from ultraviolet radiation. Oneof these compounds has the following mass percentages: 58.6%Cl and9.93%C.
What is the empirical formula of this compound? --------------------------------------------- A sample of an unknown biochemical compound is found to have apercent composition of 57.14% carbon, 6.17% hydrogen, 9.52%nitrogen and the balance oxygen. What is the empirical formula forthis compound ? --------------------------------- A compound is known to contain 40.45% carbon and 35.90% oxygenby mass. Each molecule contains two atoms of oxygen. What is themolar mass of this substance?

Explanation / Answer

Q1 Molar mass folic acid = 441.403g/mol 400 micrograms = 4.00 x 10-4g 4.00 x 10-4 x 1mol/441.403 g mol-1 = 9.062 x10-7 mol To fine molecules, multiply by avogadros number 9.062 x 10-7 mol x 6.022 x 1023mol-1 = ? molecules folic acid Q2 For empirical formula questions, always assume 100g 58.6% Cl = 58.6g Cl, 9.93%C = 9.93g C, andFluorine is 100-(58.6 + 9.93) = 31.47% 31.47g F Now, find the number of moles of each by dividing by molar mass Molar mass Cl =35.45g/mol             C = 12.01g/mol            F = 18.998 g/mol Moles Cl = 58.6g / 35.45g mol-1 = 1.653 mol Moles C = 9.93g / 12.01 g mol-1 = 0.827 mol Moles F = 31.47g / 18.998 g mol -1 = 1.653 mol Now divide by lowest number of moles 1.653mol / 0.827 mol = 2.00 mol Cl 0.827 mol / 0.827 mol = 1.00 mol C 1.653 mol / 0.827 mol = 2.00 mol F This gives you the subscripts for the formula.. Therefore the Empirical Formula isCxClyFz Q3 Use the exact same procedure as Q2 with the CFCs except with 4different atoms. Q4 Each molecule contains two oxygen atoms. The mass of two oxygenatoms is 32 g/mol If 35.90% of the molecule is oxygen, then 32 = 35.90% of mass 32/0.3590 =molar mass molecule Molar Mass = ?

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