Enthalpy of Neutralization Introduction Energy changes always accompany chemical reactions. If energy‚ in the form of heat‚ is liberated the reaction is exothermic and if energy is absorbed the reaction is endothermic. Thermochemistry is concerned with the measurement of the amount of heat evolved or absorbed. The heat (or enthalpy) of neutralization (∆H) is the heat evolved when an acid and a base react to form a salt plus water. Eq. 1 HNO2(aq) + NAOH(aq) → NaNO2(aq) + H2O(l) + Q Q in the
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Shown below are examples of each type of acid undergoing a reaction with sodium hydroxide. Monoprotic: HCl(aq) + NaOH(aq) → H2O(l) + NaCl(aq) Diprotic: H2SO4(aq) + 2 NaOH(aq) → 2 H2O(l) + Na2SO4(aq) Triprotic: H3PO4(aq) + 3 NaOH(aq) → 3 H2O(l) + Na3PO4(aq) Any acid that has more than one proton that undergoes a reaction with a base is called a polyprotic acid. Citric acid is a weak‚ polyprotic acid that undergoes the following reaction with sodium hydroxide. H3C6H5O7(aq) + 3 NaOH(aq) → 3 H2O(l)
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Weigh out 20.0 g of sucrose and place it into a 250-mL Erlenmeyer flask. Add 100 mL of water and gently shake until all the sucrose has dissolved. To this solution add 0.60 g of dipotassium hydrogen phosphate (K)‚ 1.8 g of sodium phosphate hydrate (Na3PO412HO) and 2.0 g of dried baker’s yeast. Vigorously shake the contents to mix them thoroughly. The Erlenmeyer flask is fitted with a one-hole rubber stopper containing a short piece of glass tubing. Latex tubing (8 -12 in.) is attached to the glass
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Writing Complete Equations Practice For each of the following problems‚ write complete chemical equations to describe the chemical process taking place. Important note: There are a few physical processes on this sheet – You can’t write an equation for a physical process! 1) When lithium hydroxide pellets are added to a solution of sulfuric acid (dihydrogen sulfate)‚ lithium sulfate and water are formed. 2) When dirty water is boiled for purification purposes‚ the temperature is brought up to
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with sodium hydroxide. Monoprotic (x=1): HCl (aq) + NaOH (aq) → H2O (l) + NaCl (aq) Diprotic (x=2): H2SO4 (aq) + 2 NaOH (aq) → 2 H2O (l) + Na2SO4 (aq) Triprotic (x=3): H3PO4 (aq) + 3 NaOH (aq) → 3 H2O (l) + Na3PO4 (aq) Any acid with more than one proton (hydrogen) is called a polyprotic acid. Citric acid is a weak‚ polyprotic acid that undergoes the following reaction with sodium hydroxide: H3C6H5O7 (aq) + 3 NaOH (aq) → 3 H2O (l) + Na3C6H5O7 (aq) You
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CHM 256: BASIC ANALYTICAL CHEMISTRY TUTORIAL 1: INTRODUCTION: ANALYTICAL CHEMISTRY 1. What is chemical analysis? 2. Differentiate between qualitative and quantitative analysis (Oct 2008‚ 2009‚ Dec 2009‚ Apr 2010) 3. Give 7 steps in performing any chemical analysis (Apr 2010) 4. Briefly explain how to prepare the following solutions: a) 1.0 L 10.50 % (w/v) aqueous CH3CH2CH2OH (answer : 105 g) (Oct 2006‚ Oct 2007‚ Oct 2008) b) 500 mL 2.0 M H2SO4 from a commercial reagent‚ at 90% (w/w) purity
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The addition of 6.0 M NH3 in the fifth test tube caused the formation of the deep blue [Cu(NH3)4]2+ complex. The new equilibrium was established from the dissociation reaction of Cu(OH)2 and NH3‚ and the formation of complex [Cu(NH3)4]2+. 1.0 M Na3PO4 was added to the sixth test tube‚ and formed a light blue
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Smelling salts 9 CaCO3 Limestone/chalk 10 Sodium chloride NaCl Table salt 11 Calcium chloride CaCl2 De-icer for snow on roads 12 Calcium hypochlorite Ca(ClO)2 Swimming pool disinfectant 13 Ammonium nitrate NH4NO3 Used in fertilizer 14 Ammonium phosphate Na3PO4 Used in fertilizer 15 Calcium oxide CaO Used to make plaster 16 Carbon dioxide CO2 Dry ice 17 Chromium oxide Cr2O3 Green pigment in paints 18 Copper sulfate CuSO4 Plant root killer 19 Iron(III) chloride FeCl3 Etching solution 20 Magnesium carbonate
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x +(2*2) = 0 ‚ x = 4 b)Sn in SnCl3- : +2 x +( 3* -1 = -1 x=2 c)N in N2H4 : -2 = 2x + 4(1) = 0 x = -2 d) C in C2O4 -2 : +3 2x + (-2) 4 = -2 x= 3 e)N in HNO2): +3 f) Cr in Cr2O72- +6 4.56) a) Mn(s) + NiCl2 (aq) -> MnCl2((aq))+Ni(s) b) Cu(s) + Cr(C2H3O2) (aq)-> NR C) 2Cr(s)+ 3NiSO4(aq) -> Cr2(SO4)3(aq)+ 3Ni(s) d) Pt(s) + HBr(aq) -> NR e) H2 (g) + CuCl2 (aq) -> Cu(s) + 2HCl (aq) 4.64) Calculate the mol of Na + at the two concentrations;
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Datalogging Experiment (4) Acid-base Titration using Method of Double Indicators Student Handout Purposes To determine the composition of the following mixture by double indicator method: 1. NaOH(aq) and Na2CO3(aq) 2. NaHCO3(aq) and Na2CO3(aq) Introduction Consider a mixture of NaOH(aq) and Na2CO3(aq). Reaction between HCl(aq) and Na2CO3(aq) takes place in two stages: HCl(aq) + Na2CO3(aq) ⎯→ NaHCO3(aq) + H2O(l) …………………. (1) HCl(aq) + NaHCO3(aq) ⎯→ NaCl(aq) + CO2(g) + H2O(l) …………. (2) While
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