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Published byHortense Small Modified over 9 years ago
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Neutralization, Titration & Concentration
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Neutralization For an acid to effectively neutralize a base (or vice versa) the number of moles of acid and base must be equal
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Example How many moles of sodium hydroxide are required to neutralize 45.0 mL of a 0.120 mol/L H 2 SO 4 solution? 1. Write a balanced equation.
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2NaOH (aq) + H 2 SO 4(aq) 2H 2 O (l) + Na 2 SO 4(aq) 2. Determine the # of moles to be neutralized (calculate the number of moles of H 2 SO 4 )
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2NaOH (aq) + H 2 SO 4(aq) 2H 2 O (l) + Na 2 SO 4(aq) 3. Use the coefficients to calculate the number of moles required for neutralization.
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Extension 2NaOH (aq) + H 2 SO 4(aq) 2H 2 O (l) + Na 2 SO 4(aq) 4. If you used 30.0 mL of NaOH to neutralize the H2SO4, what is the concentration of the NaOH?
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Titrations Requirements: – Standard an acid or base where you know the [concentration] – Indicator a substance in which the completed titration (change from acidic to basic or vice versa) will be demonstrated by a colour change
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Titrations cont’d When the concentration of the acid and the base are equal, we have reached the “equivalence point” This is where: #Moles acid = #moles base The end point is reached when one drop of titrate permanently changes the colour of the indicator
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Vinegar (aka Acetic Acid) was titrated with Sodium Hydroxide to determine the concentration of acetic acid present. A volume of 41.6 mL of 1.00 mol/L NaOH was required to neutralize a 50.0 mL sample of vinegar, indicated by a pink colour change. What was the concentration of the vinegar? 1. Write a balanced equation
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2. Calculate the moles of the standard that were required to neutralize the unknown concentration of vinegar * At the equivalence point the moles acid = moles base
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NaOH (aq) + CH 3 COOH (aq) CH 3 COONa (aq) + H 2 O 3. Use the coefficients to figure out the mole ratio (notice it is 1:1 in this equation and therefore #moles CH 3 COOH = #moles NaOH
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Calculate the concentration of CH 3 COOH
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Example: How many moles of sodium hydroxide are required to neutralize 0.20 moles of nitric acid?
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Example: How many millilitres of 0.45 mol/L HCl solution must be added to 25.0 mL of a 1.00 mol/L KOH solution to make a neutral solution?
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