CHEMISTRY FORM 4 PREPARATION FOR

STANDARDIZED TEST

QUESTION 1:

An experiment is conducted to investigate the effect of temperature on the rate of reaction. 5 set of 50cm3 of 1.0 mol dm-3 sulphuric acid is reacted with 5g of magnesium ribbon at a different temperature.

DOES THE TEMPERATURE AFFECT THE RATE OF REACTION BETWEEN SULPHURIC ACID AND MAGNESIUM RIBBON?

a) State a problem statement for above experiment.

[2 m ]

b) Identify all the variables in this experiment.

i) Manipulated variable

ii) Responding variable

iii) Controlled variable

TEMPERATURE OF ACID

RATE OF REACTION

CONCENTRATION AND VOLUME OF ACID, MASS OF MAGNESIUM RIBBON

c) State one suitable hypothesis for this experiment.

THE HIGHER THE TEMPERATURE , THE HIGHER THE RATE OF REACTION BETWEEN SULPHURIC ACID AND MAGNESIUM RIBBON.

QUESTION 2:A group of students has carried out an experiment to determine the melting point of substance Y. A boiling tube contained substance Y solid is heated in a water bath. The temperature of substance Y is recorded every 30 seconds. The result is as shown in table 2 below.

Time(min)

0 ½ 1 1½ 2 2½ 3 3½

Temp.(o C)

60.0 64.0 68.0 72.0 76.0 80.0 80.0 80.0

Time(min)

4 4 ½ 5 5½ 6 6½ 7 7½

Temp.(o C)

80.0 80.0 80.0 80.0 80.0 83.0 86.0 89.0

a) Draw a graph of the temperature against time for the experiment and locate the melting point for substance Y [4 m]

b) Explain why there is no change in temperature from min 2½ to 6 min

HEAT ABSORB BY THE PARTICLES IS USE TO OVERCOME THE ATTRACTIVE FORCES BETWEEN THE PARTICLES

c) Draw the arrangement of particles at 2 minutes of heating. [1m]

QUESTION 3Table 3 shows the proton number and nucleon number for atom V, W, X, Y and Z

Atom Proton number

Nucleon number

V 1 1W 1 2X 3 7Y 6 12Z 20 40

Based on information given in Table 3, answer the following questions.

a) What is meant by nucleon number? [1 m]TOTAL NUMBER OF PROTON AND NEUTRON IN THE NUCLEUS OF AN ATOM

b) What is the number of neutron for particle W ? [1 m] 1

c) Write the electron arrangement for atom: [1 m]V : 1

Z: 2.8.8.2

d) Draw the structure of atom X

[1 m]

e) Which of the above atoms are isotopes? Explain your answer. [2 m]

V AND W. BOTH ATOMS HAVE SAME PROTON NUMBER BUT DIFFERENT NUCLEON NUMBER

ORV AND W. BOTH ATOMS HAVE SAME NUMBER OF PROTON BUT DIFFERENT NUMBER OF NEUTRON

f) How many valence electrons in atom X? [1 m]

Electron arrangement: 2.1

Therefore; valence electron = 1

Seminar form four= revision for selaras 1- april 2011

4) An experiment was conducted in order to determine the empirical formula of magnesium oxide.a) Give the meaning of empirical

formula.IS THE FORMULA THAT GIVES THE

SIMPLEST WHOLE NUMBER RATIO OF ATOM OF EACH ELEMENT IN A

COMPOUND

–Why must the magnesium ribbon be cleaned with sandpaper?

–Why does the crucible need to be

covered with its lid as soon as the magnesium start burning?

TO REMOVE THE OXIDE LAYER

TO PREVENT THE WHITE FUMES FROM ESCAPING

d) Description Mass, gMass of crucible + lid 22.30Mass of crucible + lid + magnesium 24.70Mass of crucible + lid + magnesium oxide

26.30

i) Calculate the mass of mg used. MASS OF Mg = (24.70-22.30)

= 2.4 g

ii) Calculate the mass of oxygen that reacts with magnesium.

iii) Calculate the number of moles of magnesium used.

MASS OF OXYGEN = 26.30-24.70 = 1.6

MOLE OF MAGNESIUM = 2.4 / 24 = 0.1

iv) Calculate the number of moles of oxygen that has reacted.

MOLE OF OXYGEN = 1.6/16 = 0.1

v) Determine the empirical formula of magnesium oxide. Mg: O

0.1 : 0.11 : 1MgO

The reaction between hydrochloric acid and zinc carbonate was written below. hydrochloric acid + zinc carbonate zinc chloride + carbon dioxide + water

a) Write the chemical formula for zinc chloride.

Rewrite the equation above as chemical equation. [2 m]

hydrochloric acid + zinc carbonate zinc chloride + carbon dioxide + water

HCl +2 ZnCO3

ZnCl2 + CO2 + H2O

If 12.5 g of zinc carbonate react completely in the reaction above calculate,i) the number of mole of hydrochloric acid being used? [3m]

2HCl + ZnCO3 ZnCl2 + CO2 + H2O

ii) the mass of zinc chloride obtained. 2HCl + ZnCO3

ZnCl2 + CO2 + H2O

iii) the vol of gas collected at room temp

2HCl + ZnCO3 ZnCl2 + CO2 + H2O