1.During oxidation of 112l (n. o.s.) of ammonia with oxygen on platinum catalyst nitrogen oxide (III) was obtained in 80% yield of the product. Determine the mass of the resulting product in grams:a)60; c)90; c)120; e)180; f)200; 2. What volume (n. o.s.) of 98% sulfuric acid solution with a density of 1.84g/ml must be taken to prepare 1,044ml of 12% sulfuric acid solution with a density of 1.08g/ml:a)75ml; c)80ml; c)85ml; e)90ml; f)100ml;

3) What volume (in ml) of a solution with a mass fraction of sulfuric acid of 0.8 and a density of 1.78 g/ml must be taken to prepare 275 ml of a 12% solution of this acid with a density of 1.08 g/ml? (a) 21 ml; (c) 22 ml; (d) 23 ml; (e) 24 ml; (f) 25 ml;

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.

може ли да зареждате повече информация, моля

a. the law of proportion states the combination of 2 atoms in a specific ratio to produce multiple compounds such as the given statement of question ‘1st compound contains 88.8 % cu ’ indicates 88.8 g of cu is present along with 11.2 g oxygen in 100 g of compound whereas the statement ‘2st compound contains 79.9 % cu ’ indicates 79.9 g of cu is present along with 20.1 g oxygen in 100 g of compound

1st compound contains 88.8 g cu

for cu

m = 63 g /mol

atomic % = 88.8 /63 = 1.42

for o

m = 16 g /mol

atomic % = 11.2 /16 = 0.7

b. the emperical formula of 1st compound is

cu1.4o0.7

cu2o