Question

the percentage by weight of O2 in CaSo4 ( O =16, S =32 Ca =40 ) is
a. 64
b. 28.2
c. 47.2
d. 16.2​

Answer 1

Explanation:

Formula unit mass of CaSO4.2H2O

= (Number Calcium atoms x atomic mass of Calcium) + (Number Sulphur atoms x atomic mass of sulphur) + (Number Oxygen atoms x atomic mass of Oxygen) + (Number Water molecules x Molecular mass of water molecule)

=(1×40)+(1×32)+(4×16)+(2×18)

=40+32+64+36

=172

Formula unit mass of gypsum = 172

Ans is option C

Hope it helps...

Please mark me as brainlist.

Answer 2

Answer:

Option C : 47.2 %

Explanation:

The percentage by weight of O2 in CaSO4 is 47.2%.

Given :

O = 16

S = 32

Ca = 40

To find :

Percentage by weight of O2

Solution :

We know that,

CaSO4 contains 1 molecule of Ca + 1 molecule of S + 4 molecules of O

∵ CaSO4 = (1 * 40) + (1 * 32) + (4 * 16)

∵ CaSO4 = 40 + 32 + 64

∵ CaSO4 = 136 grams

Now,

1 molecule of O = 16 grams

∴ 4 molecules in CaSO4 = 4 * 16 = 64 grams.

Now,

Percentage of O2 in CaSO4 = $\frac{Mass of O2}{Mass of CaSO4} * 100$

∴ Percentage of O2 in CaSO4 = $\frac{64}{136} * 100$

∴ Percentage of O2 in CaSO4 = 47.2 %

∴ The percentage by weight of O2 in CaSO4 is 47.2%.

#SPJ3