Question

Please help me with this please fast

Answer 1

Let the Atomic mass of Element X be : P amu

Where : 1 Atomic mass unit (amu) = 1.66 × 10⁻²⁴ grams

As Molar mass of an Element is equal to Atomic mass of respective element  expressed in grams, We can say that :

$:\implies$  One mole of atoms of Element X weighs : P grams

Let the Atomic mass of Element Y be : Q amu

$:\implies$  One mole of atoms of Element Y weighs : Q grams

Given : 0.1 mole of XY₂ has weight 10 grams

$:\implies$  1 mole of XY₂ weighs 100 grams

We should realize that : One mole of XY₂ contains One mole of X atoms and One mole of Y₂ Molecules

$:\implies$  1 mole of X atoms + 1 mole of Y₂ molecules = 100 grams

☆  Weight of 1 mole of Y₂ Molecules = Weight of 2 Moles of Y atoms

$:\implies$  1 mole of X atoms + 2 moles of Y atoms = 100 grams

$:\implies$  P grams + 2Q grams = 100 grams

$:\implies$  P + 2Q = 100 -------- [1]

Given : 0.05 mole of X₃Y₂ has a weight 9 grams

$:\implies$  0.1 mole of X₃Y₂ has a weight of 18 grams

$:\implies$  1 mole of X₃Y₂ has a weight of 180 grams

One mole of X₃Y₂ contains One mole of X₃ Molecules and One mole of Y₂ Molecules

$:\implies$  1 mole of X₃ Molecules + 1 mole of Y₂ molecules = 180 grams

☆  Weight of 1 mole of X₃ Molecules = Weight of 3 Moles of X atoms

$:\implies$  3 mole of X atoms + 2 moles of Y atoms = 180 grams

$:\implies$  3P grams + 2Q grams = 180 grams

$:\implies$  3P + 2Q = 180 -------- [2]

Subtracting Equation [1] from Equation [2], We get :

$:\implies$  (3P + 2Q) - (P + 2Q) = 180 - 100

$:\implies$  (3P - P) + (2Q - 2Q) = 80

$:\implies$  2P = 80

$:\implies$  P = 40

$:\implies$  One mole of atoms of Element X weighs : 40 grams

$:\implies$  Atomic mass of Element X  : 40 amu  

Substituting value of P in Equation [1], We get :

$:\implies$  40 + 2Q = 100

$:\implies$  2Q = 100 - 40

$:\implies$  2Q = 60

$:\implies$  Q = 30

$:\implies$  One mole of atoms of Element Y weighs : 30 grams

$:\implies$  Atomic mass of Element Y  : 30 amu

Answers :

$\bigstar\;\;\textsf{Atomic mass of Element X = 40 amu}$

$\bigstar\;\;\textsf{Atomic mass of Element Y = 30 amu}$