Question

If elements X and Y are combined to form two compounds $XY_2$ and $X_2Y_3$, weight of 0.005 moles of $XY_2$ is 5 gram and weight of $3.01\times10^{23}$ molecules of $X_2Y_3$ is 85 gram. Find out the atomic mass of X and Y.​

Answer 1

Answer:

Explanation:

Basic Concepts of Chemistry:-First of all,there is a slight mistake in question.It has to be 0.05 moles of XY2,instead of 0.005.Let gram atomic mass of X be a grams,and of Y be b grams.

There is a formula which is to be applied:-No. of moles=Given mass/Molar massAlso 1 mole contains 6.02*10^23 molecules (Avogadro's law)We get two equations,on solving them,we get:-a=40g,b=30g

Hence, atomic mass of X is 40g,and that of Y is 30g.

Answer 2

Answer:

x = 40,  y = 30

Explanation:

Mass  / Molarmass  = Mole

5g / mw = 0.05  

mw = 100

x + 2y =100  ..........(1)

no: of molecules / 6*10^23 = mass/mw

eq(1) * 2

3.011×10^23 / 6.023×10^23  = 85 / mw

mw = 170

2x+3y=170  .........(ii)

On solving equation (i) and (ii), we get-

2x+4y=200

2x+3y=170

y=30

2×x+3×30=170

2x=170−90

2x=80

x=40

  therefore x = 40

                 y = 30

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