Module 2A Chemical Formula and Equations I

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TUISYEN IBNU SINA CHEMISTRY MODULE 2CHEMICAL FORMULAE AND EQUATIONS

Relative molecular mass and relative formula mass

1. Calculate the relative molecular mass of the following substances

Molecule Molecular formula Relative molecular mass

Oxygen O2

Bromine Br 2

Carbon dioxide CO2

Hydrogen chloride HCl

Water H2O

Ammonia NH3

[Relative atomic mass: O,16;Br,80;C,12;H,1;Cl,35.5;N,14]

2. Calculate the relative formula mass of the following substances

CompoundCompound

formulaRelative formula mass

Sodium chloride NaCl

Calcium carbonate CaCO3

Magnesium nitrate Mg(NO3)2

Copper(II) sulphate CuSO4

Aluminium oxide Al2O3

Lead(II) iodide PbI2

Hydrated copper(II) sulphate CuSO4.5H2O

[Relative atomic mass: Na,23; Cl,35.5;Ca,40;C,12;O,16;Mg,24;N,14;Cu,64;S,32;Al,;Pb,;I,]

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Number of molesThe relationship between number of moles and number of particles and mass.

1) Given that there is 0.5 moles of chlorinegas. Calculate the

a) Number of chlorine molecules.

b) Number of chlorine atoms.

2) Given that there is 4.82 x 1021 hydrogenatoms in hydrogen gas . Calculate the

a) Number of moles of hydrogen atoms.

b) Number of moles of hydrogenmolecules

3) Given that there is 0.5 moles carbondioxide gas. Calculate the

a) Number of moles ofcarbondioxide molecules.

b) Number ofoxygenatoms.

4) Given that there is 1.806 x 1024 nitrogenatoms. Calculate the

a) Number of moles of nitrogen atoms.

b) Number of moles of nitrogenmolecules.

5) Given that there is 2.5 moles ofmagnesium chloride, MgCl2. Calculatethe

a) Number of magnesium ion, Mg2+.

6) Calculate the number of moles ofa) 2.8 g of iron,

[RAM: Fe,56]

2

moles mass (g)

X RAM / RMM

RAM / RMMparticles

X (6.02 x 1023 )

(6.02 x 1023 )


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b) Total number of ions in MgCl2 b) 10 g of calcium.[RAM: Ca, 40]

7) Calculate the mass ofa) 3 moles of copper atoms.

[RAM: Cu,64]

b) 0.4 moles of water molecules, H2O.[RAM: H,1; O,16]

c) 2.5 moles of magnesiumcarbonate, MgCO3.[RAM: Mg, 24; C,12; O,16]

8) Calculate the number of moles of thefollowing substances.a) 8 g of copper(II) oxide,CuO

[RAM: Cu,:64;O,16]

b) 2.5 g of zinc carbonate, ZnCO3[RAM:Zn,65;C,12;O,16]

9) Calculate the mass of 1.204 x 1021

Copper atoms.[RAM: Cu,64]

10) Calculate the number of calcium atoms in

100 g of calcium.[ RAM: Ca,40]

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11) Calculate the number of oxygen atomsin 1.6 g of oxygen gas.[RAM: O,16]

12) Calculate the number of molecules thatare present in 0.44g of carbondioxide,CO2.[RAM:C,12;O,16]

13) Calculate the number of moles of720cm3 CO2 gas at room condition.[Molar volume : 24dm3mol-1 at roomcondition]

14) Calculate the number of moles of 560cm3

nitrogen gas at room condition.[Molar volume : 24dm3mol-1 at roomcondition]

15) Calculate the volume of gas that isoccupied by 0.3 mol of oxygen at STP?[Molar volume : 22.4 dm3mol-1 at STP]

16) Calculate the volume of gas that isoccupied by 0.125 mol of sulphur dioxideat STP?[Molar volume : 22.4 dm3mol-1 at STP]

Chemical formulae

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Complete the following table with the right chemical formula.

Anion

Cation

Cl-

Chloride

ion

NO3-

Nitrate

ion

OH-

Hydroxide

ion

SO42-

Sulphate

ion

CO32-

Carbonate ion

O2-

Oxideion

Na+

Sodiumion

Mg2+

Magnesium ion

Fe2+

Iron(II)ion

K+

Potassium ion

Cu2+

Copper(II) ion

Pb2+

Lead(II)ion

Li+

Lithiumion

Zn2+

Zinc ion

Ca2+

Calcium ion

Ba2+

Bariumion

Chemical equation

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Write and balance the chemical equations below using symbols

N CHEMICAL EQUATIONs

1 Sodium + Chlorine sodium Chloride

2 Zinc + Oxygen Zinc oxide

3 Ethene + Oxygen Carbon dioxide + water

4 Lead(II)nitrate decomposes to produces lead(II)oxide, nitogen and oxygen

5 Sodium thhiosulphate + hydrochloric acid sodium chloride + sulphurdioxide +

sulphur + water

6 Copper + silver nitrate Copper(II)nitrate + silver

7 Barium(II) nitrate + sodium sulphate Barium(II)sulphate + sodium nitrate

8 Potassium + water Potassium hydroxide + hydrogen

9 Propanol + Oxygen Carbon dioxide + water

1 Ethane + oxygen Carbon dioxide

UNDERSTANDING CHEMICAL EQUATION

Solve the following calculation problems by using chemical equations.2Mg(s) + O2(g) 2MgO(s)

What is the mass of the oxide formed if 1.2g of magnesium is burnt completely in excessof oxygen? [Relative atomic mass : Mg,24;O,16]

2. CaCO3(s) + 2HCl(aq) CaCl2(aq) + CO2(g) + H2O(l)What is the maximum volume of carbon dioxide gas released when 2g of calciumcarbonate reacts with excess of hydrochloric acid.[Relative atomic mass: Ca,40;C,12;O,16;H,1;Cl,35.5][Molar volume : 22.4dm3mol-1 at STP]

3. Cu(s) + 2AgNO3(aq) Cu(NO3)2(aq) + 2Ag(s)What is the mass of copper powder used to produced 48.6g of silver metal.[Relative atomic mass : Cu,64;Ag,108;N,14;O,16]

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Module 2A Chemical Formula and Equations I