(i) A compound has the following percentage composition by mass: carbon 14.4%, hydrogen 1.2% and chlorine 84.5%. Determine the empirical formula of this compound. Work correct to 1 decimal place. (H = 1; C = 12; Cl = 35.5) (ii) The relative molecular mass of this compound is 168, so what is it's molecular formula?

(i) Element | % composition | At. wt. | Relative no. of atoms| Simplest ratio --------|---------------|---------|----------------------|---- Carbon | 14.4 | 12 | = 1.2 | = 1 Hydrogen | 1.2 | 1 | = 1.2 | = 1 chlorine | 84.5 | 35.5 | = 2.38 | = 1.98 = 2 Simplest ratio of whole numbers = C : H : Cl = 1 : 1 : 2 Hence, empirical formula is CHCl 2 Empirical formula weight = 12 + 1 + 2(35.5) = 84 g Relative molecular mass = 168 Molecular formula = n[E.F.] = 2[CHCl 2 ] = C 2 H 2 Cl 4 Molecular formula = C 2 H 2 Cl 4

(a) A hydrate of calcium sulphate CaSO4.xH₂O contains 21% water of crystallisation. Find the value of x.
(b) What volume of hydrogen and oxygen measured at S.T.P. will be required to prepare 1.8 g of water.
(c) How much volume will be occupied by 2g of dry oxygen at 27°C and 740 mm pressure?
(d) What would be the mass of CO₂ occupying a volume of 44 litres at 25°C and 750 mm pressure?
(e) 1 g of a mixture of sodium chloride and sodium nitrate is dissolved in water. On adding silver nitrate solution, 1.435 g of AgCl is precipitated.
AgNO₃ (aq) + NaCl (aq) ⟶ AgCl (s) + NaNO₃
Calculate the percentage of NaCl in the mixture.

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From the equation:
C + 2H₂SO₄ ⟶ CO₂ + 2H₂O + 2SO₂
Calculate:
(i) The mass of carbon oxidized by 49 g of sulphuric acid.
(ii) The volume of sulphur dioxide measured at STP, liberated at the same time.

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Find the percentage of
(a) oxygen in magnesium nitrate crystals [Mg(NO₃)₂.6H₂O].
(b) boron in Na₂B₄O₇.10H₂O. H=1,B=11,O=16,Na=23.
(c) phosphorus in the fertilizer superphosphate Ca(H₂PO₄)₂

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What mass of copper hydroxide is precipitated by using 200 g of sodium hydroxide?
2NaOH + CuSO₄ ⟶ Na₂SO₄ + Cu(OH)₂ ↓
[Cu = 64, Na = 23, S = 32, H = 1]

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Chemistry

Mole Concept

Related Questions

From the equation:
C + 2H₂SO₄ ⟶ CO₂ + 2H₂O + 2SO₂
Calculate:
(i) The mass of carbon oxidized by 49 g of sulphuric acid.
(ii) The volume of sulphur dioxide measured at STP, liberated at the same time.

Find the percentage of
(a) oxygen in magnesium nitrate crystals [Mg(NO₃)₂.6H₂O].
(b) boron in Na₂B₄O₇.10H₂O. H=1,B=11,O=16,Na=23.
(c) phosphorus in the fertilizer superphosphate Ca(H₂PO₄)₂

What mass of copper hydroxide is precipitated by using 200 g of sodium hydroxide?
2NaOH + CuSO₄ ⟶ Na₂SO₄ + Cu(OH)₂ ↓
[Cu = 64, Na = 23, S = 32, H = 1]

Chemistry

Mole Concept

Related Questions

From the equation:C + 2H2SO4 ⟶ CO2 + 2H2O + 2SO2Calculate:(i) The mass of carbon oxidized by 49 g of sulphuric acid.(ii) The volume of sulphur dioxide measured at STP, liberated at the same time.

Find the percentage of(a) oxygen in magnesium nitrate crystals [Mg(NO3)2.6H2O].(b) boron in Na2B4O7.10H2O. H=1,B=11,O=16,Na=23.(c) phosphorus in the fertilizer superphosphate Ca(H2PO4)2

What mass of copper hydroxide is precipitated by using 200 g of sodium hydroxide?2NaOH + CuSO4 ⟶ Na2SO4 + Cu(OH)2 ↓[Cu = 64, Na = 23, S = 32, H = 1]

From the equation:
C + 2H₂SO₄ ⟶ CO₂ + 2H₂O + 2SO₂
Calculate:
(i) The mass of carbon oxidized by 49 g of sulphuric acid.
(ii) The volume of sulphur dioxide measured at STP, liberated at the same time.

Find the percentage of
(a) oxygen in magnesium nitrate crystals [Mg(NO₃)₂.6H₂O].
(b) boron in Na₂B₄O₇.10H₂O. H=1,B=11,O=16,Na=23.
(c) phosphorus in the fertilizer superphosphate Ca(H₂PO₄)₂

What mass of copper hydroxide is precipitated by using 200 g of sodium hydroxide?
2NaOH + CuSO₄ ⟶ Na₂SO₄ + Cu(OH)₂ ↓
[Cu = 64, Na = 23, S = 32, H = 1]