Novdec Chemistry trial

*CHEMISTRY TRAILS*
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1)What's is enthalpy change of reaction?
b)State the type of enthalpy change that exist in each of the f.f processes
i)C3H8 + 5O2 ---------->3CO2 + 4H20
ii)NaOH +H20 ----------->NaOH
iii)HCl + NaOH -------------> NaCl + H20

2)Consider the following solutions:
Na2So4;CH3COOK;Pb(NO3)2 and MgCl

i)Which of them has /have the a pH?
ii)equal to 7
iii)less than 7

3.Define the ff terms
a.saturated solution
b.Standardized solution

4.Name the precipitate formed when aqueous solutions of the ff pairs of the compounds are mixed:
I.AgNO3 and MgCl2
ii.Pb(NO3)2 and Na2C03
iii.ZnSO4 and BaCl2

5.a.Give the main constituents and one use of each of the ff alloys:
I)Duralumin. ii)Brass

b.Name two substances that act as reducing agents in the extraction of iron and write equations to show their reducing action.