How do i solve this Volume question- Chemistry

Watch
mind
Badges: 1
Rep:
? You'll earn badges for being active around the site. Rep gems come when your posts are rated by other community members.
#1
Report Thread starter 7 years ago
#1
I am revising A-level Chemistry and the question states:

Ammonia is bought as “880 ammonia” (a solution of density 0.880 g cm-3), whose content is 28% ammonia (i.e. it contains 280 g ammonia per kilogram of solution). What volume of the “880 ammonia” solution would you need to prepare 1.0 dm3 of 2.0 mol dm-3 ammonia solution ?

How would i get the answer: 0.138 L

Here are some equations:

n=m/Mr n=C x V/1000 therefore V=n/c x1000
0
reply
TSR Learn Together
Badges: 9
Rep:
? You'll earn badges for being active around the site. Rep gems come when your posts are rated by other community members.
#2
Report 7 years ago
#2
Hi there,

While you're waiting for an answer, did you know we have 300,000 study resources that could answer your question in TSR's Learn together section?

We have everything from Teacher Marked Essays to Mindmaps and Quizzes to help you with your work. Take a look around.

If you're stuck on how to get started, try creating some resources. It's free to do and can help breakdown tough topics into manageable chunks. Get creating now.

Thanks!

Not sure what all of this is about? Head here to find out more.
0
reply
charco
Badges: 18
Rep:
? You'll earn badges for being active around the site. Rep gems come when your posts are rated by other community members.
#3
Report 7 years ago
#3
(Original post by mind)
I am revising A-level Chemistry and the question states:

Ammonia is bought as “880 ammonia” (a solution of density 0.880 g cm-3), whose content is 28% ammonia (i.e. it contains 280 g ammonia per kilogram of solution). What volume of the “880 ammonia” solution would you need to prepare 1.0 dm3 of 2.0 mol dm-3 ammonia solution ?

How would i get the answer: 0.138 L

Here are some equations:

n=m/Mr n=C x V/1000 therefore V=n/c x1000
Find out how many moles of ammonia is needed for your target solution.

Now work out the molarity of your stock solution.

Now determine what volume of your stock solution contains the number of moles needed for your target solution.
0
reply
Borek
  • Study Helper
Badges: 4
Rep:
? You'll earn badges for being active around the site. Rep gems come when your posts are rated by other community members.
#4
Report 7 years ago
#4
Alternatively, instead of finding molarity of the 880 solution, find what mass of the ammonia is needed (from number of moles in the target solution), then find what mass of 28% solution contains needed mass of ammonia, and finally find volume of that solution from known density.

This approach doesn't call for finding or deriving conversion equation between w/w percentage and molarity - so I would get the final answer faster this way. YMMV.
0
reply
X

Quick Reply

Attached files
Write a reply...
Reply
new posts
Back
to top
Latest
My Feed

See more of what you like on
The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

Personalise

Would you give consent for uni's to contact your parent/trusted person in a mental health crisis?

Yes - my parent/carer (118)
33.71%
Yes - a trusted person (95)
27.14%
No (93)
26.57%
I'm not sure (44)
12.57%

Watched Threads

View All
Latest
My Feed