{"id":21,"date":"2014-10-21T09:39:44","date_gmt":"2014-10-21T09:39:44","guid":{"rendered":"http:\/\/blogs.glowscotland.org.uk\/gc\/hyndsechchemu3hwrk\/volumetric-analysis\/"},"modified":"2014-10-21T09:52:10","modified_gmt":"2014-10-21T09:52:10","slug":"volumetric-analysis","status":"publish","type":"page","link":"https:\/\/blogs.glowscotland.org.uk\/gc\/hyndsechchemu3hwrk\/volumetric-analysis\/","title":{"rendered":"Volumetric Analysis"},"content":{"rendered":"

1.<\/strong>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 25 cm3<\/sup> of a solution of sodium hydroxide was added to a flask and titrated with a 0.2 mol l-1<\/sup> solution of hydrochloric acid.<\/p>\n

HCl + NaOH <\/em><\/strong>\u2192<\/em><\/strong> NaCl + H2<\/sub>O<\/em><\/strong><\/p>\n

The experiment was carried out three times and the volumes of HCl titrated in each experiment are shown in the table.<\/p>\n\n\n\n\n\n\n
Titration<\/td>\nVolume of 0.2 mol l-1<\/sup> solution of HCl (cm3<\/sup>)<\/td>\n<\/tr>\n
1<\/td>\n11.3<\/td>\n<\/tr>\n
2<\/td>\n10.4<\/td>\n<\/tr>\n
3<\/td>\n10.6<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\u00a0<\/p>\n

Calculate the concentration of the NaOH solution in mol l \u20131<\/sup>.<\/p>\n

2.<\/strong>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 20 cm3<\/sup> of a solution of potassium hydroxide was added to a flask and titrated with a 0.1 mol l-1<\/sup> solution of hydrochloric acid.<\/p>\n

\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 HCl + KOH \u2192 KCl + H2<\/sub>O<\/p>\n

The experiment was carried out three times and the volumes of HCl titrated in each experiment are shown in the table.<\/p>\n\n\n\n\n\n\n
Titration<\/td>\nVolume of 0.2 mol l-1<\/sup> solution of HCl (cm3<\/sup>)<\/td>\n<\/tr>\n
1<\/td>\n20.6<\/td>\n<\/tr>\n
2<\/td>\n19.9<\/td>\n<\/tr>\n
3<\/td>\n20.0<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\u00a0<\/p>\n

Calculate the concentration of the KOH solution in mol l \u20131<\/sup>.<\/p>\n

3.<\/strong>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 10 cm3<\/sup> of a solution of KOH was added to a flask and titrated with a 0.05 mol l-1<\/sup> solution of H2<\/sub>SO4<\/sub>.<\/p>\n

\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 H2<\/sub>SO4<\/sub> + 2KOH \u2192 K2<\/sub>SO4<\/sub>\u00a0 + 2H2<\/sub>O<\/p>\n

The experiment was carried out three times and the volumes of HCl titrated in each experiment are shown in the table.<\/p>\n\n\n\n\n\n\n
Titration<\/td>\nVolume of 0.2 mol l-1<\/sup> solution of HCl (cm3<\/sup>)<\/td>\n<\/tr>\n
1<\/td>\n15.9<\/td>\n<\/tr>\n
2<\/td>\n15.2<\/td>\n<\/tr>\n
3<\/td>\n15.3<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\u00a0<\/p>\n

Calculate the concentration of the KOH solution in mol l \u20131<\/sup>.<\/p>\n

4.<\/strong>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 Rhubarb leaves contain oxalic acid, (COOH)2<\/sub>. A pupil found that it required 17 cm3<\/sup> of 0.001 mol l-1<\/sup> of sodium hydroxide to neutralise 25 cm3<\/sup> of a solution made from rhubarb leaves.\u00a0 Calculate the concentration of oxalic acid in the solution given that the equation for the reaction is:<\/p>\n

\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 (COOH)2<\/sub> + 2NaOH \u00e0 Na2<\/sub>(COO)2 <\/sub>+ 2H2<\/sub>O<\/p>\n

5.<\/strong>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 Acidified potassium permanganate can be used to determine the concentration of hydrogen peroxide solution; the solutions react in the ratio of<\/p>\n

\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 2 mol of potassium permanganate: 5mol of hydrogen peroxide.<\/strong><\/p>\n

In an analysis it is found that 16.8 cm3<\/sup> of 0.025 mol l-1<\/sup> potassium permanganate reacts exactly with a 50 cm3<\/sup> sample of hydrogen peroxide solution. What is the concentration, in mol l-1<\/sup> of the hydrogen peroxide solution?<\/p>\n

6.<\/strong>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 Iodine reacts with thiosulphate ions as follows:<\/p>\n

\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 I2<\/sub>(aq)\u00a0 +\u00a0\u00a0\u00a0 2S2<\/sub>O3<\/sub>2-<\/sup>(aq)\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 2I –<\/sup>(aq)\u00a0\u00a0\u00a0\u00a0 +\u00a0\u00a0\u00a0 S4<\/sub>O6<\/sub>2-<\/sup>(aq)<\/p>\n

In an experiment it was found that 1.2 x 10-5<\/sup> mol of iodine reacted with 3.0 cm3<\/sup> of the sodium thiosulphate solution.\u00a0 Use this information to calculate the concentration of the thiosulphate solution in mol l-1<\/sup>.<\/p>\n

7.<\/strong>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 Vitamin C, C6<\/sub>H8<\/sub>O6<\/sub>, is a powerful reducing agent. The concentration of vitamin C in a solutioncan be found by titrating it with a standard solution of iodine, using starch as an indicator. The equation for the reaction is:<\/p>\n

\u00a0\u00a0\u00a0\u00a0\u00a0 C6<\/sub>H8<\/sub>O6<\/sub>(aq)\u00a0 +\u00a0 I2<\/sub>(aq)\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 C6<\/sub>H6<\/sub>O6<\/sub>(aq)\u00a0\u00a0 +\u00a0\u00a0\u00a0 2H+<\/sup>(aq)\u00a0\u00a0 +\u00a0 2I–<\/sup>(aq)<\/p>\n

A vitamin C tablet was crushed and dissolved in some water. The solution was then transferred \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 to a standard 250 cm3<\/sup> flask and made up to the 250 cm3<\/sup> mark with distilled water.<\/p>\n

In one investigation it was found that an average of 29.5 cm3 <\/sup>of 0.02 mol l-1<\/sup> iodine solution was \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 required to react completely with 25.0 cm3 <\/sup>of vitamin C solution.<\/p>\n

Use this result to calculate the mass, in grams, of vitamin C in the tablet.<\/p>\n

8.<\/strong>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 Hydrogen sulfide, H2<\/sub>S, can cause an unpleasant smell in water supplies. The concentration of hydrogen sulfide can be measured by titrating with a chlorine standard solution. The equation for the reaction taking place is<\/p>\n

\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 4Cl2(aq) <\/sub>\u00a0+ H2<\/sub>S(aq)<\/sub> \u00a0+ 4H2<\/sub>O(<\/sub>l<\/sub>)<\/sub> \u2192 SO4<\/sub>2\u2212<\/sup>(aq) <\/sub>+ 10H+<\/sup>(aq)<\/sub> \u00a0+ 8Cl\u2212<\/sup>(aq)<\/sub><\/p>\n

50\u00b70 cm3<\/sup> samples of water were titrated using a 0\u2219010 mol l\u22121<\/sup> chlorine solution.<\/p>\n

(a) Name an appropriate piece of apparatus which could be used to measure out the water \u00a0samples.<\/p>\n

(b) What is meant by the term standard solution?<\/p>\n

(c) An average of 29\u00b74 cm3<\/sup> of 0\u2219010 mol l\u22121 <\/sup>chlorine solution was required to react completely with a 50\u00b70 cm3<\/sup> sample of water. Calculate the hydrogen sulfide concentration, in mol l\u22121<\/sup>, present in the water sample. Show your working clearly.<\/p>\n

9.<\/strong>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 A compound known as ethylenediaminetetraacetic acid (EDTA) is useful for measuring the \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 quantities of certain metal ions in solution.\u00a0 For example, Ca2+<\/sup> ions and EDTA react in a 1 mol:1 mol ratio.<\/p>\n

It is found that 14.6 cm3<\/sup> of 0.1 mol l-1<\/sup> EDTA reacts exactly with a 25cm3\u00a0 <\/sup>sample of a solution containing Ca2+<\/sup> ions.\u00a0<\/p>\n

Calculate the concentration, in mol l-1<\/sup>, of the calcium ion solution.<\/p>\n

\u00a0<\/strong><\/p>\n

10.\u00a0\u00a0\u00a0\u00a0\u00a0 <\/strong>Trichloromethane , is insoluble in water.\u00a0 When ammonia is added to the beaker containing water and trichloromethane, the ammonia dissolves in bith solvents giving different concentrations.<\/p>\n

\u00a0<\/strong><\/p>\n

\u00a0<\/strong><\/p>\n

\u00a0<\/strong><\/p>\n

\u00a0<\/strong><\/p>\n

\u00a0<\/strong><\/p>\n

\u00a0<\/strong><\/p>\n

\u00a0<\/strong><\/p>\n

\u00a0<\/strong><\/p>\n

\u00a0<\/strong><\/p>\n

\u00a0<\/strong><\/p>\n

\u00a0<\/strong><\/p>\n

\u00a0<\/strong><\/p>\n

is called the partition coefficient.<\/p>\n

This can be found by titrating the ammnia in each layer against diluute hydrochloric acid.<\/p>\n

(a) How could the end points of the titrations be observed?<\/p>\n

(b) The concentration of ammonia in water was calculated from three titrations.<\/p>\n

The titre volumes were as follows<\/p>\n

1st<\/sup> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 24.7 cm3<\/sup><\/p>\n

2nd<\/sup> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 24.0 cm3<\/sup><\/p>\n

3rd<\/sup>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 23.9 cm3<\/sup><\/p>\n

(c) What volume of dilute hydrochloric acid would be used to calculate the concentration of water in ammonia?<\/p>\n

(d) The concentration of ammonia in water was found to be 1.7 mol \u2113-1<\/sup>.\u00a0 For the ammonia in terachloromethane, it was found that 18.4 cm3<\/sup> of dilute hydrochloric acid, concentration\u00a0 0.050 mol \u2113-1<\/sup> was required to neutralise 20 cm3<\/sup> of the ammonia solution.<\/p>\n

(e) Calculate the value for the partition coefficient of ammonia between water and trichloromethane.<\/p>\n

11.<\/strong> A 50\u00b70cm3 <\/sup>sample of contaminated water containing chromate ions was titrated and found t require 27\u00b74 cm3<\/sup> of 0\u00b70200 mol \u2113 \u20131<\/sup> iron(II) sulphate solution to reach the end-point.<\/p>\n

The redox equation for the reaction is:<\/p>\n

\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 3Fe2+<\/sup>(aq) + CrO4<\/sub>2\u2013<\/sup>(aq) + 8H+<\/sup>(aq) \u2192 3Fe3+<\/sup>(aq) + Cr3+<\/sup>(aq) + 4H2<\/sub>O(\u2113 )<\/p>\n

Calculate the chromate ion concentration, in mol l\u20131<\/sup>, present in the sample of water.<\/p>\n

\u00a0<\/strong><\/p>\n

12.<\/strong>\u00a0\u00a0\u00a0\u00a0\u00a0 An average of 21\u00b76cm3<\/sup> of 0\u00b70150 mol \u2113 \u20131<\/sup> acidified permanganate solution was required to react completely with the nitrite ions in a 25\u00b70 cm3<\/sup> sample of river water.<\/p>\n

The equation for the reaction taking place is:<\/p>\n

2MnO4<\/sub>\u2013<\/sup>(aq) + 5NO2<\/sub>\u2013<\/sup>(aq) + 6H+<\/sup>(aq) \u2192 2Mn2+<\/sup>(aq) + 5NO3<\/sub>\u2013<\/sup>(aq) + 3H2<\/sub>O(\u2113)<\/p>\n

Calculate the nitrite ion concentration, in mol l\u20131<\/sup>, in the river water.<\/p>\n","protected":false},"excerpt":{"rendered":"

1.\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 25 cm3 of a solution of sodium hydroxide was added to a flask and titrated with a 0.2 mol l-1 solution of hydrochloric acid. HCl + NaOH \u2192 NaCl + H2O The experiment was carried out three times and the volumes of HCl titrated in each experiment are shown in the table. Titration Volume … Continue reading “Volumetric Analysis”<\/span><\/a><\/p>\n","protected":false},"author":2454,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"open","ping_status":"open","template":"","meta":{"footnotes":""},"class_list":["post-21","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/blogs.glowscotland.org.uk\/gc\/hyndsechchemu3hwrk\/wp-json\/wp\/v2\/pages\/21","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blogs.glowscotland.org.uk\/gc\/hyndsechchemu3hwrk\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/blogs.glowscotland.org.uk\/gc\/hyndsechchemu3hwrk\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/blogs.glowscotland.org.uk\/gc\/hyndsechchemu3hwrk\/wp-json\/wp\/v2\/users\/2454"}],"replies":[{"embeddable":true,"href":"https:\/\/blogs.glowscotland.org.uk\/gc\/hyndsechchemu3hwrk\/wp-json\/wp\/v2\/comments?post=21"}],"version-history":[{"count":1,"href":"https:\/\/blogs.glowscotland.org.uk\/gc\/hyndsechchemu3hwrk\/wp-json\/wp\/v2\/pages\/21\/revisions"}],"predecessor-version":[{"id":51,"href":"https:\/\/blogs.glowscotland.org.uk\/gc\/hyndsechchemu3hwrk\/wp-json\/wp\/v2\/pages\/21\/revisions\/51"}],"wp:attachment":[{"href":"https:\/\/blogs.glowscotland.org.uk\/gc\/hyndsechchemu3hwrk\/wp-json\/wp\/v2\/media?parent=21"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}