Balance the following four equations on the line provided by writing the symboli

Question

Balance the following four equations on the line provided by writing the symbolic equation with the appropriately correct coefficients. (60)

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1. Zinc reacts with hydrochloric acid

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2. ammonium chloride reacts with potassium hydroxide

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3. pentane (C5H12) burns (reacts with oxygen)in the engine of your lawn mower

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4. aluminum bromide reacts with silver nitrate

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5. 92.4 g. of water cool from 85oC to 8.2oC. Determine the amount of heat lost. With this heat, what mass of water could have its temperature raised 20oC? (20)

6. Determine the specific heat of iron if 40.22 g. of the material can be heated from 12.4oC to 25.1oC by 38.30 joules. (20)

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1. Zinc reacts with hydrochloric acid

__________________________________________________________________________

2. ammonium chloride reacts with potassium hydroxide

__________________________________________________________________________

3. pentane (C5H12) burns (reacts with oxygen)in the engine of your lawn mower

___________________________________________________________________________

4. aluminum bromide reacts with silver nitrate

___________________________________________________________________________

5. 92.4 g. of water cool from 85oC to 8.2oC. Determine the amount of heat lost. With this heat, what mass of water could have its temperature raised 20oC? (20)

6. Determine the specific heat of iron if 40.22 g. of the material can be heated from 12.4oC to 25.1oC by 38.30 joules. (20)

Explanation / Answer

1) Zn + 2HCl -> ZnCl2 + H2

2) NH4Cl + KOH -> NH4OH + KCl

3) C5H12 + 8O2 -> 5CO2+ 6H2O

4) AlBr3 + 3AgNO3 -> Al(NO3)3 + 3AgBr

5) Mass = 92.4gm
Temperature change = 85 - 8.2 = 76.80C
Specific Heat = 4.2 Joules/gm Celcius
   Heat evolved = mass * specific heat * temperature change= 92.4 *4.2 * 76.8 =29,804 Joules

For rising 200C, mass = Heat/ (specific heat* Temperature change)
= 29,804/(4.2*20)
   = 354.8gm

6) Mass = 40.22 gm
   Energy = 38.3 Joules
   Temperature Change = 25.1 -12.4 = 12.7oC
   specific heat = 38.3/40.22*12.7
   = 0.075 Joules/gmCelcius

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