chemistry question

[perrychan527]

The melting temp of benzoic acid is 122'C. The student's sample was impure. Suggest how the melting temp of the sample would differ from that of pure benzoic acid.
Aan: lower than 122'C. Melt over a range of temp/sharp.
Can anyone explain it? Thank mates

2. now KMnO4 is titrated against Fe(II) solution. When making up the solution of the iron(II) salt, another student, by mistake, added too much dilute sulphuric acid to the graduated flask before shaking the contents so that the total volume was over 250cm3. Explain the effect this mistake would have on the student's volume of potassium manganate(VII) solution used in the titration.
Ans: The volume of potassium manganate(VII) used will be smaller than the correct figure.
can anyone explain? thanks

[perrychan527]

anyone can help???

[nid404]

1) Melting points of impure substances happens over a range of temperatures, lower than the pure substance.  You must know this.

2) I need to see the whole question.

[cashem'up]

The melting temp of benzoic acid is 122'C. The student's sample was impure. Suggest how the melting temp of the sample would differ from that of pure benzoic acid.
Aan: lower than 122'C. Melt over a range of temp/sharp.
Can anyone explain it? Thank mates

2. now KMnO4 is titrated against Fe(II) solution. When making up the solution of the iron(II) salt, another student, by mistake, added too much dilute sulphuric acid to the graduated flask before shaking the contents so that the total volume was over 250cm3. Explain the effect this mistake would have on the student's volume of potassium manganate(VII) solution used in the titration.
Ans: The volume of potassium manganate(VII) used will be smaller than the correct figure.
can anyone explain? thanks

1 . nid already answered
2 . now when u are titrating u are asked to make a solution of 250 cm3 of iron salt howeevr it goes above 250 bcos u added more h2SO4. Now usually u r supposd to pippete 25cm3 out of this 250......so now there will be less mole fe per cm3 or in simpler terms......just imagine u will have less Fe in 25cm3 as there will be slightly more H2SO4 than usual and thus less KMNo4 is reqd to complete the reaction

[abuelzouz]

is this cie or edexcel

[cashem'up]

is this cie or edexcel

no idea the point is its chemistry........lolz