Question

A. . The balanced equation for the combustion of ethanol is 2C2H5OH(g) + 7O2(g)  4CO2(g) + 6H2O(g) How many grams of dioxygen are required to burn 5.9 g of C2H5OH? B. 2Al(s) + 6HCl(aq)  2AlCl3(aq) + 3H2(g) According to the equation above, how many grams of aluminum are needed to completely react with 3.83 mol of hydrochloric acid? C. What is the formula for the chlorate of gadolinium(III)? D. What is the formula for the nitride of samarium(III)? E. An excess of sodium hydroxide is treated with 2.4 L of dry hydrogen iodide gas measured at STP.(STP means Temp =273.15K What is the mass of sodium iodide is formed?

Answer 1

A)

2C2H5OH (l) + 7O2 (g) ----> 4 CO2 9g) + 6H2O (g)

Molar mass of C2H5OH = 46 g/mol
mass of C2H5OH = 5.9 g

number of moles of C2H5OH = mass/ molar mass
                                           = 5.9 / 46
                                           =0.1283 mol

From reaction given above, 2 mol of C2H5OH requires 7 mol of O2.
0.1283 moles of C2H5OH will require = 7*0.1283/2 = 0.449 mol of O2

Molar mass of O2 = 32 g
mass of O2 required = molar mass of O2 * number of moles of O2
                              = 32 * 0.449
                              = 14 g