(a) A flask contains 3.2 g of sulphur dioxide. Calculate the following :
(i) The moles of sulphur dioxide present in the flask.
(ii) the number of molecules of sulphur dioxide present in the flask.
(iii) the volume occupied by 3.2 g of sulphur dioxide at STP.
(S = 32, O = 16)
(b) A n experiment showed that in a lead chloride solution 6.21 g of lead is combined with 4.26 g of chlorine. What is the empirical formula of this chloride?
(Pb = 2107; Cl = 35.5).

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Solution

A)
The molar mass of SO2 is 64 g
1. Number of moles of SO2 in flask = Given mass of SO2/Molar mass
= $fraction numerator 3.2 g over denominator 64 space g m o l to the power of negative 1 end exponent end fraction$
= 0.05 moles
2. Number of molecules of SO2 = Number of moles x Avogadro Number
= 0.05 x 6.022 x
= 3.01 x molecules of
3. Volume occupied by the SO2 at S.T.P : PV = nRT (1)
P = 1 atm
n = 0.05 moles
R = 0.0821 L atm
T = 273 K
Putting the values in eq (1) we get
V = $fraction numerator 0.05 cross times 0.0821 cross times 273 over denominator 1 end fraction$
= 1.12 L
OR
Volume occupied of 1 mole of gas at STP = 22.4 L
Therefore volume occupied by 0.05 mole of gas = 22.4 L x 0.05
= 1.12 L
b) Wt. of Pb=6.21g

Wt. of Cl= 4.26g

total wt. = 10.47

$T h e r f o r e, p e r c e n t a g e o f P b = 6.21 \div 10.47 \times 100 = 59.3$

$p e r c e n t a g e o f C l = 4.27 \div 10.47 \times 100 = 40.69$

element % At. Wt. Relative ratio Simple ratio

Pb 59.7 207 59.7/207=0.286 0.286/0.286=1

Cl 40.69 35.5 40.69/35.5=1.46 1.46/0.286=4

$t h e r e f o r e, e m p i r i c a l f o r m u l a = P b C l_{4}$

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Similar questions

(a) A flask contains 3.2 g of sulphur dioxide. Calculate the following:
(i) The moles of sulphur dioxide present in the flask.
(ii) The number of molecules of sulphur dioxide present in the flask.
(iii) The volume occupied by 3.2 g of sulphur dioxide at STP. (S = 32, O = 16)

(b) The reaction of potassium permanganate (VII) with acidified iron (II) sulphate is given below:
2KMnO₄ + 10FeSO₄ + 8H₂SO₄ $\overset{}{\to}$ K₂SO₄ + 2MnSO₄ + 5Fe₂(SO₄)₃ + 8H₂O
If 15.8 g of potassium permanganate (VII) was used in the reaction, calculate the mass of iron (II) sulphate used in the above reaction. (K = 39, Mn = 55, Fe = 56, S = 32, O = 16)

A flask contains 3.2 g of sulphur dioxide. Calculate the followings:

i) The number of molecules of sulphur dioxide at STP.

ii) The volume occupied by 3.2 g of sulphur dioxide at STP.

(S = 32, O = 16)

An experiment showed that in a lead chloride solution, 6.21 g of lead combined with 4.26 g of chlorine.

What is the empirical formula of this chloride? [Pb = 207, Cl = 35.5]

Q. An experiment showed that a lead chloride solution is formed when 6.21 g of lead combines with 4.26 g of chlorine. What is the empirical formula of this chloride?

[Pb = 207; Cl = 35.5]

(a) Calculate the mass of nitrogen supplied to the soil by 5 kg of urea $[C O (N H_{2})_{2}]$
$[O = 16 : N = 14; C = 12; H = 1]$
(b) Calculate the volume occupied by 320 g of sulphur dioxide at STP $[S = 32; O = 16]$

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element	%	At. Wt.	Relative ratio	Simple ratio
Pb	59.7	207	59.7/207=0.286	0.286/0.286=1
Cl	40.69	35.5	40.69/35.5=1.46	1.46/0.286=4