Question

*️⃣
Question ❓√✔️
•√√ Work out the percentage composition of constituents elements in the following
compounds :
a) Lead phosphate
[Pb3 (PO4)2],

b) Potassium dichromate
(K2,Cr2,O7 ),


c) Macrocosmic salt - Sodium
ammonium hydrogen phosphate,tetrahydrate

(NaNH 4 HPO4 .4H2,O)


​

Answer 1

For Lead Phosphate (a) :-

Molar mass of Lead phosphate [Pb₃(PO₄)₂] :-

= 207 × 3 + (31 × 2 + 16 × 8)

= 621 + 190

= 811 g/mol

Percentage of Lead (Pb)

= 621/811 × 100

= 0.7657 × 100

= 76.57 %

Percentage Phosphorus (P)

= 62/811 × 100

= 0.764 × 100

= 7.64 %

Percentage of Oxygen (O)

= 128/811 × 100

= 0.1578 × 100

= 15.78 %

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For Potassium dichromate (b) :-

Molar mass of Potassium dichromate [K₂Cr₂O₇] :-

= (39 × 2) + (52 × 2) + (16 × 7)

= 78 + 104 + 112

= 294 g/mol

Percentage of Potassium (K)

= 78/294 × 100

= 0.2653 × 100

= 26.53 %

Percentage of Chromium (Cr)

= 104/294 × 100

= 0.3537 × 100

= 35.37 %

Percentage of Oxygen (O)

= 112/294 × 100

= 0.3810 × 100

= 38.10 %

_________________________________

For Macrocosmic salt (c) :-

Molar mass of Macrocosmic salt [NaNH₄HPO4₄.4H₂O] :-

= 23 + 14 + 4 + 1 + 31 + 64 + 4(18)

= 209 g/mol

Percentage of Sodium (Na)

= 23/209 × 100

= 0.11 × 100

= 11 %

Percentage of Nitrogen (N)

= 14/209 × 100

= 0.067 × 100

= 6.7 %

Percentage of Hydrogen (H)

= 13/209 × 100

= 0.0622 × 100

= 6.22 %

Percentage of Phosphorus (P)

= 31/209 × 100

= 0.1484 × 100

= 14.84 %

Percentage of Oxygen (O)

= 128/209 × 100

= 0.6124 × 100

= 61.24 %

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Answer 2

Answer:

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Question :-

• Work out the percentage composition of constituents elements of the following compounds.

1. Lead phosphate.
2. Potassium dichromate.
3. Macrocosmic salt.

Answers :-

1. (Lead phosphate) The mass percentage composition of constituents elements of lead phosphate is Pb= 76.57%,P=7.64%,15.78%.
2. (Potassium dichromate) The mass percentage composition of constituents elements of potassium dichromate is K=26.53%,Cr=35.35%,O=38.07%.
3. (Macrocosmic salt) The mass percentage composition of constituents elements of macrocosmic salt is Na=11%,N=67%,H=6.22%,P=14.84%,O=61.24%.

Given :-

• The mass percentage composition of constituents elements of compounds are given such as

1. Lead phosphate
2. Potassium dichromate
3. macrocosmic salt.

To find :-

• The mass percentage composition of constituents of given elements.

Solution :-

• Here refer the given attachment for better understanding.
• I cant do in this only because of network issues. So u can refer the given above attachment.

Used formulae : -

• Here we used the formula that is

• %=mass of element in 1 mole / molar mass of given compound.

Hope it helps u mate.

Thank you .