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WAJA F5 Chemistry Chapter 4 : Thermochemistry

CHAPTER 4 : THERMOCHEMISTRYANSWERActivity 1(a) (1) transferred , (2) increases ,(b) (3) absorbs , (4) decreases

Activity 2

(a) Identify the following reactions as exothermic or endothermic reaction

Reaction Exothermic Endothermic(a) Combstion of ethanol !(b) "rning of magnesim !(c) #etralisation between acid and al$ali !(d) %dding water to concentrated sl&hric acid !(e) 'hotosynthesis !(f) Reaction between acid and magnesim !(g) Reaction between acid and calcim carbonate !

(h) issoling ammonim salt in water !(i) *hermal decom&osition of co&&er(ll) carbonate !(+) *hermal decom&osition of inc nitrate !

(b) (1) -. , (2) $/, (3) negatie sign , (4) higher , (0) &ositie sign(c) Twoother exam&les of exothermic and endothermic reaction

Exothermic reaction Endothermic reaction1) 'hysical changes gas liid

liidsolid

'hysical changes solid liid ,

liidgas2) Reaction between reactie metals

(sodim and &otassim) with water Rsting of iron

issoling crystalline salts in water

exam&le C5460.25

Activity 3

(a) (i) 7g 8 .254 7g54 8 .2 -. 9 :4;< $/

(ii) CaC53 Ca5 8 C52 -. 9 8 1

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WAJA F5 Chemistry Chapter 4 : Thermochemistry

(iii) (1) inc , (2) co&&er(II) sl&hate , (3) exothermic , (4) increases , (0) inc ,

(;) co&&er(II) sl&hate , (? $/ , (>) inc , (1?) co&&er(II) sl&hate, (11) one , (12) one , (13) 1>? , (14) &rodced released (10) hydrogen gas, (1;) iodine gas, (1) hydrogen gas (2?) iodine gas, (21) less , (22) 03 , (23) hydrogen gas , (24) iodine gas , (20) two , (2;) 03 (2

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WAJA F5 Chemistry Chapter 4 : Thermochemistry

its salt soltion by a more electro&ositie metal6

(b) (1) 1?0? / , (2) one , (3) one , (4) ?62 x 20 9 ?6??0, (0) ?6??0 mol , (;) ?6??0 1??? () : 21? $/ mol:1

?6??0

(1?) Energy leel diagram

(c) -. 9 : 1;6 = $/ mol :1

(d) 336= ?C

Activity 7

(a) *he heat of netraliation is the heat change when one mole of water is formed from thereaction between an acid and an al$ali6

(b) (1) 136? , (2) 136? , (3) 04;? / , (4) .Cl 8 #a5.#aCl 8 .25 , (0) .88 5.:.25 (;) 1 , () ?61 mol , (1?) ?61 mol , (11) ?61 mol , (12) ?61 mol , (13) 04;? /,

(14) 04;? 9 04;??/ 9 046; $/ , (10) : 046; $/ mol:1 ?61

(1;) Energy leel diagram

(c) 060 $/(d) ;6= ?C

Activity 8

(a) *he heat of combstion is the heat change when one mole of a sbstance is com&letely

brnt in oxygen nder standard conditions6

(b) (1) 202?? /, (2) 352, (3) 2C52, (4) 3.25 , (0) ?6

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WAJA F5 Chemistry Chapter 4 : Thermochemistry

(=) 202?? /, (>) 202?? 9 104;?1262 / 9 104; $/ ,?6?1;3

(1?) Energy leel diagram

(c) (1) 326? , (2) 3?6? , (3) 316? , (4) C.35. , (0) C3.5. , () 4 (1?) 32 , (11) ;? , (12) < , (1;) 2;==? /

(1)