Seminar revision on chapter intro to chemistry, structure of atom, chemical formula and equations

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 50cm 3 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? ,[object Object]

[object Object],[object Object],[object Object],[object Object],TEMPERATURE OF ACID RATE OF REACTION ,[object Object]

[object Object],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 3 Table 3 shows the proton number and nucleon number for atom V, W, X, Y and Z Atom Proton number Nucleon number V 1 1 W 1 2 X 3 7 Y 6 12 Z 20 40

[object Object],[object Object],TOTAL NUMBER OF PROTON AND NEUTRON IN THE NUCLEUS OF AN ATOM

[object Object],1 ,[object Object],V : 1 Z: 2.8.8.2

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

[object Object],Electron arrangement: 2.1 Therefore; valence electron = 1

Seminar form four= revision for selaras 1- april 2011

[object Object],[object Object],IS THE FORMULA THAT GIVES THE SIMPLEST WHOLE NUMBER RATIO OF ATOM OF EACH ELEMENT IN A COMPOUND

[object Object],[object Object],[object Object],TO REMOVE THE OXIDE LAYER TO PREVENT THE WHITE FUMES FROM ESCAPING

[object Object],MASS OF Mg = (24.70-22.30) = 2.4 g d) Description Mass, g Mass of crucible + lid 22.30 Mass of crucible + lid + magnesium 24.70 Mass of crucible + lid + magnesium oxide 26.30

[object Object],[object Object],MASS OF OXYGEN = 26.30-24.70 = 1.6 MOLE OF MAGNESIUM = 2.4 / 24 = 0.1

[object Object],MOLE OF OXYGEN = 1.6/16 = 0.1 ,[object Object],Mg: O 0.1 : 0.1 1 : 1 MgO

[object Object],[object Object]

Rewrite the equation above as chemical equation. [2 m] hydrochloric acid + zinc carbonate  zinc chloride + carbon dioxide + water HCl + 2 ZnCO 3  ZnCl 2 + CO 2 + H 2 O

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 + ZnCO 3  ZnCl 2 + CO 2 + H 2 O

ii) the mass of zinc chloride obtained. 2HCl + ZnCO 3  ZnCl 2 + CO 2 + H 2 O

iii) the vol of gas collected at room temp 2HCl + ZnCO 3  ZnCl 2 + CO 2 + H 2 O

Seminar revision on chapter intro to chemistry, structure of atom, chemical formula and equations

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