revision chap 3

8/13/2019 Revision Chap 3

1/12

CHAPTER 3

CHEMICAL FORMULAE

AND EQUATIONS

REVISION


2/12

earning TargetsA student should be able to:

Understand and apply the concepts of relative atomic mass and

relative molecular mass

Analyze the relationship between the number of moles and the

number of particles

Analyze the relationship between the number of moles of a

substance and its mass

Analyze the relationship between the number of moles of a gas and

its volumeSynthesize chemical formulae

Interpret chemical equations

Practice scientific attitudes and values in investigating matter


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CONCEPT MAPFORMULAE AND CHEMICAL EQUATIONS

Atom

Empirical formula Chemical formula Molecular formula

Products of

reactionReactants Chemical equation

Volume ofgas

Number of

particlesNumber ofmoles

Molecule

Relative atomic

mass,Ar

in gram

Relative

molecular mass

Relative

atomic mass

Relative molecular

mass,Mr

in gramMass of

matter

Molar mass


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GANBATTEMINNA SAN


5/12

QUESTIONS Chapter 2) State the processes involve in the changes of

states of matter. (from solid to liquid and viceversa)

What is sublimation? State the examples ofsubstances that undergo sublimation process.

What is nucleon number?

What are isotopes?

What is the use of C-14 isotope, cobalt-60 andradioisotopes?


6/12

QUESTIONS Chapter 3) What is the meaning of relative atomic mass?

What is the meaning of relative molecular

mass?

Why C-12 is used as a standard?

Adrenaline is produced by the adrenal gland.

Adrenaline has the formula C9

H13

NOx

. If itsr.m.m. is 183, determine the value of x.


7/12

QUESTIONS Chapter 3) What do you understand about Avogadros

number/constant, NA?

Calculate the number of particles in:

a)0.75 mole of aluminium atoms, Al

b)1.2 mole of chloride ions, Cl-

c)0.07 mole of carbon dioxide molecules, CO2.

[r.a.m.: Al=27, Cl=35.5, C=12, O=16, NA=6 X

1023mol-1]


8/12

QUESTIONS Chapter 3) Calculate the mass of the following substances:

a)1.2 X1022zinc atoms

[r.a.m.: Zn=65, NA=6 X 1023mol-1]

Calculate the number of molecules present at s.t.p. in

a)0.28 dm3 of N2gas

b)448 cm3

of carbon monoxide, CO gas[1 mole of gas occupied a volume of 22.4 dm3 at

s.t.p., NA= 6 X 1023mol-1]


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QUESTIONS Chapter 3)

What is empirical formula? What is molecularformula?

A gaseous hydrocarbon X contains 85.7% of

carbon by weight. 4.2g of the gas X occupies avolume of 3.36 dm3at s.t.p.

a)Determine the empirical formula of X.

b)Determine the relative molecular mass of X.

c)What is the molecular formula of X?

[r.a.m.:H=1, C=12; 1 mol of gas occupies a volumeof 22.4 dm3at s.t.p.]


10/12

QUESTIONS Chapter 3)Write the chemical formulae of: Solid calcium carbonate reacts with aqueous

hydrochloric acid to form calcium chloride,carbon dioxide gas and water.

What is reactant? What is products? How do youdifferentiate reactant and product?

Write down the symbols which appear in a

chemical equation for heating substance, gasevolved, precipitate formed, reversible reaction,react, produced/yields, solid state, liquid state,gas state and aqueous state.


11/12

QUESTIONS Chapter 3)

The chemical name of baking powder is sodiumbicarbonate (NaHCO3). When sodium bicarbonate isheated, it decomposes to sodium carbonate, carbondioxide and water.

a)Write a balanced chemical equation for thedecomposition of sodium bicarbonate when it isheated.

b)If 2.1g of sodium bicarbonate is heated, calculate the

volume in cm3

of CO2produced at room temperature.[r.a.m.: H=1,C=12,O=16,Na=23; 1 mol of gas occupies avolume of 24 dm3 at room temperature]


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revision chap 3

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