1* 10^22 molecules of Cuso. 5H2o was added to water and 100 g solution was obtained by weight of CuSO..5H2O in the solution is (Atomic weight of Cu = 63.5) (1) 41.59 g (2) 4.159 g (3) 415.9 g (4) 24.6 g
Answers
Answer:
(2) 4.159g
Explanation:
you must use avogadro number in this question. but don't put the value of 6.023*10^23 even though that is precise, your math skills are needed, and not your calculator skills. hence the question was designed to put the options as answers which you will get only by solving with your maths skills and application. so put 6*10^23 as your value of your Avogadro number.
18u is mass of water
cuso4.5h20 molecular weight = 63.5+ 32 +16(4) + 5(18)
= 249.5u
1mol = 249.5g= 6*10^23 molecules of cuso4. 5h20
10^22 molecules = 6*10^23/6*10=1mol/60
=249.5/60=4.159g = option 2
the trick here is to not worry about what is happening when it is added with water. we don't care about the water that it is added to. all the question wants is to get answer of weight of cuso4. 5h20.
if they are asking for solution formula, then
weight of cuso4. 5h20= 4.159g
weight of water that it is added to is = 100-4.159
as given in question, solution weight us 100g.
100-4.159= 95.841g
95.841/18 is the no. of moles of water. since 18 is molecular weight of water.
so, no. of moles of water ( solvent) = 5.3 mols
hence reaction is
cuso4. 5h20 +5.3h20 = cuso4 + 10.3 h20.