Question

Hitunglah berapa gram CO(NH2)2 Mr=60 yang dilarutkan kedalam 468 gram air (Mr=18), sehingga tekanan uap jenuh larutan pada temperature 30°C = 28,62 mmHg. Jika pada temperature ini tekanan uap jenuh air murni sama dengan 31,8 mmHg!

Answer 1

Δp = P° - P
P = P° . Xp
28,62 = 31,8 . ( np / (nt + np) )
nt= mol terlarut
np =  mol pelarut
nt= gr/60
np = 468/18 = 26

28,62 = 31,8 ( 26 / (gr/60 + 26)
28,62 ( gr/60 + 26) = 31,8 (26)
28,62gr/60 + 28,62 (26) = 31,8 (26)
28,62gr/60 = (31,8 - 28,62 )26
28,62gr/60 = 3,18 . 26
28,62gr = 60(82,68)
gr = 4960,8 / 28,62
gr = 173 gram

Answer 2

Mr urea = 60
massa air = 468 gram
Mr air = 18
P = 28,62 mmHg
P° = 31,8 mmHg
i = 1 karena larutan non-elektrolit
massa urea = ?

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mol air = massa / Mr = 468 / 18 = 26

P = X air × P°
28,62 = X air × 31,8
X air = 0,9

X air = mol air / (mol air + mol urea)
0,9 = 26 / (26 + mol urea)
mol urea = 2,89

massa urea = mol × Mr = 2,89 × 60 = 173,4 gram

semoga dapat membantu yah kak