100% verified Neco Gce Chemistry obj/theory Nov/dec

*MR"p"* _CHEMISTRY SOLUTIONS

*OBJECTIVES SOLUTIONS*

1-10: AAEBBDCAAC
11-20: ABBEBDDBCD
21-30: BABDCECEEC
31-40: CBDEBBBCBB
41-50: AECBBEDBDE
51-60: ACEBDCCEDB

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*THEORY SOLUTIONS*

2a.

1) Temporary hardness is caused by dissolved calcium hydrogencarbonate (which is removed by boiling).

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2) Permanent hardness is caused by dissolved calcium sulfate (which is not removed by boiling).

2b

1) Temporary Hardness can be Removed By Boiling

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2)Permanent hardness can be removed by … washing soda (sodium carbonate); ion exchange; the use of polyphosphate water softeners.

2bii)
*Advantages*

—Calcium ions in the water are good for children’s teeth and bones.

—Some brewers prefer using hard water for making beer.

2c)

A saturated solution is a chemical solution containing the maximum concentration of a solute dissolved in the solvent.

2ci
saturated solution is used in chemistry to define a solution in which no more solute can be dissolved in the solvent. It is understood thatsaturation of the solution has been achieved when any additional substance that is added results in a solid precipitate or is let off as a gass

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4di) i – Ammonia
ii – hydrochloric acid (HCl)
iii) Diagram A

4dii) i- NaCl
ii- sodium bicarbonate
iii –
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5a
i) increasing the surface area
By adding catalyst to the reaction

5iii)0.896dm^3 of CO2 was produced by 4g of caco3

5. If 100g of caco3—–1mole of co2(22.4dm3)
4g——X
X=4*22.4/100
X=0.896dm3
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