4NH3 + 5O2 → 6H2O + 4NO

1. How many moles of H2O are produced if 8 mol of NH3 are combined with excess oxygen?
2. How many grams of H2O are produced if 1.9 mol of NH3 are combined with excess oxygen?
3. How many grams of H2O are produced if 68 grams of NH3 are combined with excess oxygen?

number of molecules / avogadro's number * molecule molecular = mass

explanation:

we define a gram-molecular weight as the mass of one mole of any element or compound. a mole contains avogadro's number of units (molecules) –  

6.022

x

10

23

. so, dividing the number of molecules by avogadro's number gives us the number of moles. multiplying that by the molecular weight gives us the mass. from the periodic table we find the gram-molecular weight of u to be238 and of f to be19. so,  

u

f

6

will have a gram-molecular weight of 352g.

warm front forms when a moist, warm air mass slides up and over a cold air mass. as the warm air mass rises, it condenses into a broad area of clouds. a warm front brings gentle rain or light snow, followed by warmer, milder weather.

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