ok i need some chemistry help asap. The chloride of an element Z reacts with water according to the following equation: ZCl4 + 2h20 --->zO2 + 4HCl A 1.304 g sample of ZCl4 was added to water. The solid ZO2 was removed by filtration and the resulting solution was made up to 250 cm3 in a volumetric flask. A 25.0cm3 portion of this solution was titrated agaisnt a 0.112 mol dm-3 solution of sodium hydroxide, of which 21.7cm3 were required to reach the end point. Use this information to calculate the number of moles of HCl produced and hence the number of moles of ZCl4 present in the sample. Calculate the relative molecular mass, Mr, of Zcl3. From your answer deduce the relative atomic mass, Ar , of the element Z and hence its identity. Any help very much appreciated.
word- if you had asked this question two years ago; I would know the answer. heh.. all I remember is 22.4 is an important number with moles -- lol (man, I miss elementary chemistry) --- sry man --- random guess tho, i bet the element is S
Ok work backwards: HCl : NaOH = 1:1 relationship as H+ + OH- = H2O. If 4 HCl are produced from 1 ZCl4 then 4x as much NaOH is needed. Its the old comparitive equation which i cant remember!! ARGH!! (M1 - V1)/x = (M2 - V2)/y or something like that, check your notes. Basically: x/y are stiochiometric ratios of HCl to NaOH (1:1) and M1 = moles of HCl, V1 = vol of HCl, M2 = moles of NaOH, V2 = vol of NaOH. Then you only have 1 unknown: moles of HCl which you work out by simple maths after plugging in the rest of the values. Then you know the moles of HCl, divide that by 4 = moles of ZCl4. Then you can get the Molec mass of the compound with n=m/M Then the Ar of Cl = 35.5 so you can get the identity of Z.
Its M2-M1/x = V2-V1/y i think. GCSE was many moons ago although im 3rd year degree level in it so i should know
Na dude, quantum mechanics will do your head I hate maths. Moles aint that bad once you get used to it.
Thanks alot Bindi, Have got so much work atm, 7 as levels (Physics,Chem,Maths,Bio,I.t,Euro studies , Gen studies)
Wail til they tell you that the 2-8-8 electron config they sold you in GCSE is a crock. Then it gets FUN! I HATE THE WAY THEY LIE TO YOU AT GCSE!
I KNOW! Not only that, but they are still telling us NOW stuff that is wrong just to simplify it. Mind you, you start blabbering on about d and f orbitals and orbital symmetrys and eg and t2g orbitals to GCSE kids and theyll start to cry 7 AS levels!! You're insane!
not insane, the teachers are +i like a challenge if you did the other sciences you will find out that they have lied to you sooooo much more. Its quite scary
