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Percentage Composition

An analysis o...

Question

An analysis of Pyrex glass showed the presence of 12.9% of $B_{2} O_{3}$ , 2.2% of $A l_{2} O_{3}$ , 3.8% of $N a_{2} O$ , 0.4% of $K_{2} O$ and the remaining was $S i O_{2}$ . What is the ratio of silicon to boron atoms in the glass?

1 : 7.3

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3.65 : 1

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1 : 4.3

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4.3 : 1

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Solution

The correct option is B $3.65 : 1$
Let us assume 100 g pyrex glass
Percentage of $B_{2} O_{3} = 12.9 %$
Mass of $B_{2} O_{3} = 12.9 g$
Percentage of $S i O_{2} = 100 - [12.9 + 2.2 + 3.8 + 0.4] = 80.7 %$
Mass of $S i O_{2} = 80.7 g$
Number of moles of $B_{2} O_{3} = \frac{Mass}{Molar mass} = \frac{12.9}{70} = 0.184$
Number of moles of boron atoms $= 2 \times 0.184$
Number of moles of $S i O_{2} = \frac{Mass}{Molar mass} = \frac{80.7}{60} = 1.345$
Number of moles of silicon atoms $= 1.345$
$\frac{Number of atoms of silicon}{Number of atoms of boron} = \frac{N_{A} \times 1.345}{N_{A} \times 0.184 \times 2} = \frac{3.65}{1}$
Where, $N_{A}$ = Avogadro′s number

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Similar questions

Q. An analysis of Pyrex glass showed the presence of 12.9% of

B_{2} O_{3}

, 2.2% of

A l_{2} O_{3}

, 3.8% of

N a_{2} O

, 0.4% of

K_{2} O

and the remaining was

S i O_{2}

. What is the ratio of silicon to boron atoms in the glass?

Q. An analysis of pyrex glass showed 12.9%

B_{2} O_{3}

, 2.2%

A l_{2} O_{3}

, 3.8%

N a_{2} O

, 0.4%

K_{2} O

and remaining is

S i O_{2}

. What is the ratio of silicon to boron atoms in the glass?

The constituents used in the manufacturing of different types of glasses are given below.

Silica( ${SiO}_{2}$ ), Sodium Carbonate ( ${Na}_{2} {CO}_{3}$ ), Calcium Carbonate ( ${CaCO}_{3}$ ), Potassium Carbonate( $K_{2} {CO}_{3}$ ), Boron Oxide ( $B_{2} O_{3}$ ), Alumina ( ${Al}_{2} O_{3}$ ) and Lead Oxide ( $PbO$ )

Choose the option/s that correctly matches the constituents and its use.

Q. What is the chief constituent of Pyrex glass ?

N a_{2} O

M g O

A l_{2} O_{3}

and

S i O_{2}

have heat of formation equal to

- 416, - 602, - 1676

and

- 911

k J m o l^{- 1}

respectively. The most stable oxide is:

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Percentage Composition

Standard XII Chemistry

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An analysis of Pyrex glass showed the presence of 12.9% of B2O3, 2.2% of Al2O3, 3.8% of Na2O, 0.4% of K2O and the remaining was SiO2. What is the ratio of silicon to boron atoms in the glass?

An analysis of Pyrex glass showed the presence of 12.9% of $B_{2} O_{3}$ , 2.2% of $A l_{2} O_{3}$ , 3.8% of $N a_{2} O$ , 0.4% of $K_{2} O$ and the remaining was $S i O_{2}$ . What is the ratio of silicon to boron atoms in the glass?