Revision balance the equation

Chemical equation

1. Balance the following equations

(a) CaCO3  CaO + CO2

(b) NaNO3  NaNO2 + O2

(c) Na + O2  Na2O

(d) NaHCO3  Na2CO2 + CO2 + H2O

(e) CH4 + O2  CO + H2O

(f) Fe2O3 + CO  Fe + CO2

(g) Fe2O3 + C  Fe + CO

(h) Al + HCl  AlCl3 + H2

(i) MnO2 + HCl  MnCl2 + Cl2 + H2O

2. 11. 3g of potassium chlorate(I) KClO is heated strongly to produce potassium chloride and oxygen in laboratory.Find the volume of gas produced at s.t.p
( 1 mole gas = 22.4dm3, K= 39, Cl=35.5 )

3. An aqueous solution of sodium thiosulphate Na2S2O3, reacts with dilute hydrochloric acid to produce sodium chloride,sulphur dioxide,sulphur and water.
If 15.8g sodium thiosulphate is used, calculate
(a) the mass of sodium chloride produce
(b) the mass of sulphur produced
(c) the volume of sulphur dioxide produced
(d) the number of molecules of sulphur dioxide produced
( S=32, O=16, Na=23, 1 mole gas at s.t.p= 22.4dm3)

4. Ammonia is obtained through the following reaction.
N2 + 3H2  2NH3
Calculate the number of moles and volumes of nitrogen and hydrogen used in the
reaction if 3.2 moles of ammonia are produce at s.t.p

5. Write down the chemical equations of thefollowing reactions
(a) Buthane,C4H10 is heated in air to produce carbon and water
(b) Ammonia reacs with copper(II) oxide to produce copper,nitrogen and water
(c) Aluminium reacts with iron(III) oxide to give iron and aluminium oxide
(d) Magnesium carbonate produces magnesium chloride,carbon dioxide and water when dilute nitric acid is added to it.

exercise 30 sept2009

Exercise : Chemical formula and equation

Answer all the question given below.

1. Determine the relative molecular mass ( or relative formula mass) of each of the following
compounds:
(a) H2SO4 (b) Cu(NO3)2
(c) CoCl2.6H2O (d) glucose, C6H12O6
( Relative atomic mass : H;1 , C;12 , N;14 , O;16, S;32, Cl;35.5, Co;59, Cu;64 )

2. Calculate the number of particles in
(a) 12.8 g copper,Cu
(b) 1.2 mole of chloride ions,Cl-
( NA = 6.02 x 1023 particles)

3. Calculate the number of atoms in
(a) 0.125 mole of methane gas,CH4
(b) 36 g of glucose, C6H12O6

4. Determine the mass for each of the following substances:
(a) 1.25 mole of helium gas
(b) 2/5 mole of cobalt,Co
( Relative atomic mass He;4 , Co;59 )

5. Calculate the mass of following substances:
(a) 1.2 x 1022 zinc atoms
(b) 3 x 1023 ethanol (C2H5OH) molecules
( C;12, H;1 , O;16, Zn;65, NA= 6.02 x 1023 )

7. Calculate the number of moles of 672 cm3 of carbon dioxide gas at s.t.p
( 1 mol gas occupies 22.4 dm3 at stp)

8. Calculate the volume occupied by 1.4 g of ethane gas,C2H4 at room temperature and pressure.
( 1 mol gas occupies a volume of 24 dm3 at room temperature)

9. Cocaine,C17H21O4 is a drug .Calculate the number of cocaine molecules present in 6.06 g of the drug
( Relative atomic mass: H;1, C;12, N;14, O;16 , Na ;14 , NA= 6.02 x 1023 )

10. Caffein contains 49.5% carbon,5.2% hydrogen,28.9% nitrogen and 16.4% oxygen by weight.
Determine the empirical formula of caffeine.
( relative atomic mass H;1, C;12, N;14 , O;16 )

Revision:Periodic Table

1. Element are arranged in the modern Periodic Table based on their
A number of protons C nucleon number
B number of neutrons D atomic radius

2. Element P is placed above element Q in the same group in the Periodic Table
If element Q has 20 protons in the nucleus of its atom ,what is the electron
arrangement for the atoms of element P?
A 2.2 C 2.8.6
B 2.8.2 D 2.8.8.2

3. Accros Periods 3, one of the properties of elements increases.Which of the
following is the property?
A Electronegativity C Boiling point
B Atomic size D Electrical conductivity

4. Oxide ions and oxygen atoms are different in their
A number of protons C number of electron
B number of neutrons D nucleon number

5. Atom X reacts with chlorine to form a covalent compound with the formula
XCl. What is atom X?

A Sodium C Barium
B Carbon D Hydrogen

6. Compound Y is made up of one metal atom and two non-metal atoms.Which are the
properties of compound Y?
I highly volatile
II Conducts electricity in liquid state
III high melting point and boiling point
IV Highly soluble in organic solvent

A I and II only C I, II and IV only
B II and III only D II, III and IV only