# Past Paper A Level Paper 3 27 June 2017Watch

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#1
A student is provided with 5.00 cm3 of 1.00 mol dm−3 ammonia solution. The studentwas asked to prepare an ammonia solution with a concentration of 0.050 mol dm−3
What volume of water should the student add?

A 45.0 cm3
B 95.0 cm3
C 100 cm3
D 995 cm3

That is the question, I found the moles of the original solution and divide that by the new concentration which gives an answer of 100cm3. However, the mark scheme shows the answer to be B or 95 cm3. Can someone explain hwo to find this number?
0
1 year ago
#2
(Original post by tom_pullinger)
A student is provided with 5.00 cm3 of 1.00 mol dm−3 ammonia solution. The studentwas asked to prepare an ammonia solution with a concentration of 0.050 mol dm−3
What volume of water should the student add?

A 45.0 cm3
B 95.0 cm3
C 100 cm3
D 995 cm3

That is the question, I found the moles of the original solution and divide that by the new concentration which gives an answer of 100cm3. However, the mark scheme shows the answer to be B or 95 cm3. Can someone explain hwo to find this number?
read the question more carefully ...!
0
#3
(Original post by charco)
read the question more carefully ...!
Thank you, I've realised my mistake now
0
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