What is the molar concentration of a potassium permanganate solution Evidence

? 4 marks

Titration of 10.0 mL of Acidified 0.100 mol/L FeSO₄(aq) with KMnO₄(aq)

Trial Final buret reading Initial buret reading (mL) Volume of KMnO­₄(aq)­ added (mL)

1. 11.3 0.1. 11.2

2. 21.9 11.3 10.2

3 32.5 21.9 10.6

4 43.1 32.5 10.6

Analysis:

10 FeSO₄(aq) + 2 KMnO₄(aq) + 8 H₂SO₄(aq) → 5 Fe₂(SO₄)₃(aq) + K₂SO₄(aq) + 2 MnSO₄(aq) + 8H₂O(l)

Make sure all your answers have the correct number of significant digits and units. 

Analysis:

1) Find average volume of KMnO₄(aq) used. 1 mark

2) Find the moles of KMnO₄(aq).  1 mark

3) What is the molar ratio (unknown:known)? 1 mark

4) Find the concentration of the FeSO₄(aq) solution. 1 mark

Ammonia is a very useful chemical; our society consumes it in huge quantities. Farmers use the pure substance in liquid form as a fertilizer. Pure liquid ammonia is called anhydrous, which means "without water," to distinguish it from aqueous solutions. In solution, ammonia has an outstanding ability to loosen dirt, oil, and grease, so it is commonly used in premixed home cleaners such as window cleaning sprays, along with other ingredients. Aqueous ammonia is also sold in most stores for household use, to be diluted at home to make solutions for cleaning and wax stripping Such solutions can legally be anywhere from 5% to 30% ammonia by weight. A student wishing to find the concentration of ammonia in a commercial solution decides to make an analysis, titrating 10.00 mL samples of NH3(aq) with a standardized solution of 1.48 mol/L HCl(aq). Her first trials use more than 50 mL (a burette full) of the acid, so she throws out the results and prepares a new ammonia sample solution by diluting the original commercial solution 10:1, that is, increasing a volume tenfold to reduce the concentration to precisely one-tenth of the original value. Using the Table found on page 332 Nelson Chemistry Textbook  complete the Analysis of her investigation report.

Table 2: Titration of 10.00 mL of NH₃(aq) with 1.48 mol/L of HCl(aq)

Trial. final burette reading (mL) initial burette reading (mL). volume of HCl (aq) added (mL). colour at endpoint

1 15.0  0.3 - yellow

2 29.1. 15.0 - green

3  43.0  29.1 - green

4    14.4  0.4    - green

 Please have your answers in the correct number of significant digits and units. 

Analysis:

1) Average volume of HCl(aq) used. 1 mark

2) Moles of ammonia used. 1 mark

3) Molar ratio of Coefficients (Unknown:Known)1 mark

4) Concentration of of the ammonia solution not including the dilution factor. 1 mark

5) Concentration of the Original ammonia solution. 1 mark (hint: diluting by 10:1)