What is the percentage by mass of oxygen in Al₂(SO₄)₃. 2H₂O?
[Al = 27, S = 32, H = 1, O = 16]

14.29%

25.39%

50.79%

59.25%

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olyezema

4 years ago

Al2(SO4)3.2H2O=
27×2+(32+16×4)3+2(2+16)=378
% by masa of O2
16×4×3+16+2=
192+32=224
224/378×100=59.25%

Anobimuhammed

7 years ago

%centage Composition Of Any Element=molar Mass Of The Element/molar Mass Of The Compound * 100. Which Means Molar Mass Of The Compound Al2(SO4)3.2H2O=27*2 + 32*3 + 16*4*3 + 2*1*2 + 2*16=54+96+192+4+32=378g/mol,Therefore Molar Mass Of The Element=192+32=224
That Is, Percentage Composition Of Oxygen In Al2(SO4)3.2H2O=224/378 * 100=22400/378=59.25% The Correct Answer Is (D) Thanks

vanya

1 year ago

D is very correct oo🌝🌚

rebel12

6 years ago

You are missing out the oxygen in the water molecule which is 32
All the oxygen in the sulphur oxide Is 4×3 ×16 which is 192 adding that of water its total of 224

gregmuna

4 years ago

The answer is C

Precious973

1 year ago

This question is absolutely wrong....the Answer I mean, what's wrong with this app sef

raph.Montella

10 years ago

The mass is 224 but wrong pairing of solutions and answers

Idowuayomideolaniyi

3 months ago

D is correct. we have to consider Oxygen of the water of crystalization also

Naomich

9 years ago

Al2(SO4)3. 2H2O?

[Al = 27, S = 32, H = 1, O = 16]

Al=2x27=54

S=3X32=96

O=12X16=192

4x1+2x16=36 (2H2O)

54+96+192+36=378

So Al=54/378x100=14.3%

Sulphur=96/378x100=25.4%

Oxygen=192/378x100= 50.79%

Therefore the percentage by mass of oxygen is 50.79% (C)ans.