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- Alkali metals
- Q and J – Q is more reactive than J; this is due to stronger metallic bond.
M and P - P is more reactive them M, this is because P requires to gain a single electron for it to react which M requires two. This indicates that it is more electronegative as compared to M. - The atomic radius of K is smaller them that of L. This is because of increase in nuclear charge across the period.
- Group (IV) period 2.
- As we move down the group, the melting point and the boiling points reduce. This is due to the subsequent increase in the atomic radius down the group which reduces the electrostatic force.
- KP3
- Ionic bond
- Street lightening
In Bulbs - H – 2 .8.8 M – 2 . 8
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- CaCO3(g) + 2HCl(aq) → CaCl2(aq) + H2O(l) + CO2(g)
- Drying agent / To dry carbon (iv) oxide
- Anhydrous calcium chloride
- C(s) + CO2(g) → 2CO(g)
- Reducing property
- Its poisonous
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- Graphite
- K – Covalent
L – weak vanderwalls forces / intermolecular forces - Forms white ppt which dissolves later to form a colourless solution
Ca(OH)2(aq) + CO2(g) → CaCO3(s) + H2O(l)
CaCO3(s) + H2O(l) + CO2(g) → Ca(HCO3)2(aq)
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- Cotton / silk / sisal / banana fibre ( Award 1mk for any correct fibre)
- Last longer
Less easily attacked by acids and alkali (Award any one correct property )
Stronger
Durable -
- Hydrolysis of ethene gas with conc sulphuric acid (deny hydrolysis of alkenes)
- Reagent - Hydrogen gas √½
Catalyst - Nickel √½ - Sodium ethoxide √ (accept the formulae )
- CH3COONa + NaOH → Na2CO3 + CH4 √
- It causes pollution since it is non biodegradable √
- Ethylethanoate √ (deny ester)
- Ester / Alkyalkanoate √
- Step I Dehydration √1/2
(IV) Oxidation √1/2 - Used in manufacturing of margarine √
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- Electrolytic cells uses electrical energy to decompose substances while electrochemical cells produces electrical energy by chemical reaction
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- Anode graphite
Cathode Zinc can - Ions more freely in paste (deny electron)
- Zn(s) → Zn2+(aq) + 2e-
- It oxidizes hydrogen gas to water. Hydrogen bubbles lowers the efficiency of the cell.
- Anode graphite
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- Cathode
2H+(aq) + 2e- → H2(g) √
Anode
4OH-(aq) → 4e- + H2O(l) + O2(g) √ - In dilute NaCl. OH- and H+ ion are preferentially discharged. The ratio of Hydrogen to oxygen atoms in water molecules is 2:1 therefore the volume of hydrogen is larger than that of oxygen.
- Chlorine √
Chloride ions are more concentrated than OH- ions in brine √ - Concentration of electrolyte
Nature of the electrodes used (award any two correct factors)
Position in electrochemical series
- Cathode
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Time t-1 8 0.125 6 0.167 5 0.200 4 0.250 3 0.330 2.5 0.400
All correct award 2mks) - scale √
Correct plotting√
Straight line√ - The rate of reaction is directly proportional to the amount of the catalyst used √
- The rate of production would be lower√ Granular MnO2 has a small surface area compared with powdered MnO2√
- KClO3
39 + 35.5 + 3(16)
= 122.5g √ ½ (molar mass of KClO3 √½)
1Mole 122.5g
? 5g
0.0408mole (moles of KClo3 √½ )
2KClO3 → 2KCl + 3O2 √½
Mole ratio 2:3 (mole ratio √½ )
0.0408
Moles of 0.0408 x 3/2 (working √½ )
Oxygen gas (moles of oxygen √½)
0.0618
24 x 0.0618 = 1. 4694dm3 (answer √½)
Total = 3mks
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- 4CH(s) + 5O2(g) → 4CO2(g) + 2H2O(l)
- Hydrocarbon
- To condense the steam
- Forms white ppt which dissolves later to form a colourless solution
Ca(OH)(aq) + CO2(g) → CaCO3(s) + H2O(l)
CaCO3(s) + H2O(l) + CO2(g) → Ca(HCO3)2(aq) - Put liquid in a boiling tube, heat at boiling. The boiling should be at 1000c at sea level.
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- Copper pyrite
Cuprite (any one)
Chalcocite - Substance X Copper (I) Oxide
Gas G Sulphur (IV) oxide (accept correct formula) - X is denser and immiscible with FeSiO3, so it is tapped off from the bottom of the vessel.
- 2Cu2O(l) + Cu2S(s) → 6Cu(s) + SO2(g) (correct balanced equation √½) (state symbol √½)
- O2 gas produced lead to acid rain
- Impure copper is used as the the anode in a solution of copper (II) sulphate where it dissolves (√½)
Cu(s) → Cu2+ + 2e- ( √½)
At the cathode pure copper in used where copper is deposited on the pure metal.(√½ )
Cu2+ + 2e- → Cu(s) (√½) - Used as electrical cables
Coins
Alloy of copper & Zinc is used in medal (any two correct uses)
- Copper pyrite
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