A. ?Hsolution of NaOH(s) Phase Change: Mass of NaOH: 1.58 g ?T for reaction A :

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Explanation / Answer

Q = Cp *DT * mass Q= 4.184 J/gC * 10.5 * 50 Q = 2196.6 J or 2197 J 2.25g yields 2197 J so 1 mole equals 40 g 1 mole is 17.78 times the amount originally given, so the energy released will also be 17.78 times the amount. so, 39063J or 39.063 kJ @i neva 4get It is understood that the solid KHP was dissolved in water before it was titrated with NaOH solution. This is how you standardize a base solution. You have to know the mass of your KHP so you can determine the amount of mole of NaOH reacted at a given volume, and hence the molar vconcentration of NaOH. To do this, start with the balance chemical equation of the reaction. KHP is a MONOPROTIC acid, meaning it only got 1 titratable acid. Thus, KHP is neutralized as follows KHP + NAOH ------> NaKP + H2O You need only 1 mol of NaOH to completely neutralize 1 mol of KHP. The molar mass of KHP is 204.22 g/mol. You have to determine the amount of KHP reacted in moles moles KHP = 1.883-g KHP (1 mol/ 204.22 g) = 0.00922 mol KHP Next, find the equivalent moles of NaOH reacted mole NaOH = 0.00922 mol KHP (1 mol NaOH/ 1 mol KHP) = 0.00922 mol NaOH Thus, the molarity of your NaOH solution is [NaOH] = 0.00922 mol / (34.85/1000) L = 0.2646 M

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