Top Posters
Since Sunday
r
4
L
4
3
d
3
M
3
l
3
V
3
s
3
d
3
a
3
g
3
j
3
Home Q & A Board Science-Related Homework Help Chemistry (Moderator: Laser_3)
New Topic  
OldSpice OldSpice
wrote...
Go to Answer
Posts: 6432
Rep: 33 0
9 years ago
An unknown hydrate of cobalt(II) cyanide, Co(CN)2 • XH2O, is heated to give 32.7% water. What is the water of crystallization (X) for the hydrate?
A) 2
B) 3
C) 4
D) 6
E) 10
Read 598 times
4 Replies
Replies
Answer accepted by topic starter
ElectricElectric
wrote...
#1
Top Poster
Posts: 6431
Rep: 694 0
9 years ago
Sign in or Sign up in seconds to unlock everything for free
1
.silent.boss

Related Topics

OldSpice Author
wrote...
#2
9 years ago
Perfect!

..Thank you so much for your support
wrote...
#3
9 years ago
My pleasure
.silent.boss
wrote...
#4
2 years ago
The game plan with these is to figure out the number of moles of H2O there are per mole of CaSO4. Start by assuming any quantity of CaSO4 X H2O.

Assume 100.0 g of CaSO4 XH2O.

20.9 % of that = 20.9 g
That is the mass of water.
1 mole of water = 18.0 g
20.9 g x 1 mol/18.0 g = 1.16 mol H2O

100 % - 20.9 % = 79.1 % CaSO4
79.1 g is the mass of CaSO4
1 mole of CaSO4 = 40.1 + 32.1 + 4(16.0) = 136.2 g
79.1 g x 1 mol / 136.2 g = 0.581 mol CaSO4

Now calculate the ratio of mol H2O to mol CaSO4
1.16 / 0.581 = 2.00
So X = 2
New Topic      
Quick Reply
Explore
Post your homework questions and get free online help from our incredible volunteers
  1482 People Browsing
Start New Topic Take the Tour CoursesNew Study Tools Topics Trending Browse by Textbook
Live Chat
Related Images
  
 5737
  
 785
  
 741