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please answer the following : a) Calculate the number of molecules in 5.46 mg of

ID: 480139 • Letter: P

Question

please answer the following :

a) Calculate the number of molecules in 5.46 mg of laughing gas (N2O).

b) Calculate the mass (in grams) of 9.79 x 1013 molecules of riboflavin, C17H20N4O6.

c) The fermentation of sugar to produce ethyl alcohol occurs by the following reaction:

What mass of ethyl alcohol can be made from 0.597 kg of sugar?

d) A fast-food restaurant makes double cheeseburgers using one hamburger roll, two quarter-pound patties of beef, one slice of cheese, a fourth of a tomato, and 15 g of shredded lettuce. At the start of the day, the restaurant manager has 18 dozen rolls, 38 lb of beef patties, 4 packages of sliced cheese containing 65 slices each, 49 tomatoes, and 3 kg of lettuce. Which ingredient will run out first, and how many cheeseburgers can be made?

e) Determine the molecular formula and calculate the molar mass (in g/mol) of arginine, the essential amino acid. The formula should be entered as CwHxNyOz, followed by other element if any.

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Explanation / Answer

a)

mass of N2O = 5.46 mg = 5.46 x 10^-3 g

moalr mass of N2O = 44 g/mol

moles of N2O = 5.46 x 10^-3 / 44 = 1.24 x 10^-4 mol

for 1 mol of N2O have -------- 6.023 x 10^23 molecules

1.24 x 10^-4 mol   -------------- ?? molecules

number of N2O molecules = 1.24 x 10^-4 x 6.023 x 10^23

                                          = 7.47 x 10^19 molecules

b) Calculate the mass (in grams) of 9.79 x 1013 molecules of riboflavin, C17H20N4O6.

number of molecules = 9.79 x 1013

molar mass of riboflavin = 376 g/mol

moles of riboflavin = 9.79 x 1013 / 6.023 x 10^23

                             = 1.625 x 10^-10 mol

moles = mass / molar mass

1.625 x 10^-10 = mass / 376

mass of riboflavin = 6.11 x 10^-8 g

c)

C6H12O6 (s) -----------> 2C2H5OH(l) + 2CO2 (g)

   180 g                            92 g         

   597 g                              ??

180 g sugar ---------- 92 g ethyl alcohol

597 g sugar ------------   ??

mass of ethyl alcohol = 597 x 92 / 180

                                   = 305 g