Moles 2.. help?

Find the mass of


1a) 1mol of ammonia (NH3) ?





4.how many moles of substance are there in:


a)11g of carbon dioxide





5)find the mass of


a) 2mol of bromine atoms(Br)





7)Find the number of moles of oxygen atoms in 3 moles of CO2

Moles 2.. help?
1) 1 mol of NH3 * 17 g of NH3


---------------------- ----------------- = 17 g of NH3


1 mol of NH3





2) 11 g of CO2 * 1 mole of CO2


--------------------- -------------------- = 0.25 moles of CO2


44 g of CO2





3)2 mole of Br * 10.81 g of Br


--------------------- ------------------- = 21.62 g of Br


1 mol of Br





i'M NOT SURE ABOUT THE LAST ONE I'M STILL LEARNING THAT AND I'M NOT SURE





BUT I TRIED











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Reply:1a. 14 (mass of N) + 3 (mass of 3 H) = 17





4.a 11/12 (amount divided by the molar mass)





5. a 160 (twice the mass of Br)





7. 6 (two moles of O2 in each CO2, time 3 moles) = 6