Chemo P5 tips

[user]

guys can anyone just clear me one thing ? if there is a question on solubility and the question asks for plotting a graph for it and says to plot a line of best fit so if i dont plot a curve and instead plot a line of best fit !! will i loose a mark ??

and btw line of best fit doesnt necessarily mean thats a straight line..it cud be a curve too...dont forget that

 

[larina]

guys can anyone just clear me one thing ? if there is a question on solubility and the question asks for plotting a graph for it and says to plot a line of best fit so if i dont plot a curve and instead plot a line of best fit !! will i loose a mark ??

depends.... if the points are in a curve shape, u hav to draw a curve of best fit and if the points come in a staright line, then u have to make a staright line of best fit...

 

[Abdulrab]

but u mean to say ill not loose a mark in both the cases ?

 

[larina]

some1 explain to me dependent and independent variables ??

independent variable is what u've got on the x-axis i.e. u change it
dependent varaible is what u have on the y-axis, it varies with the independent vaireable

 

[larina]

its not gonna come !!

it can come in bio

 

[larina]

but u mean to say ill not loose a mark in both the cases ?

nope...if the points are going in a curve path, then u have to draw a curve ofcourse

 

[Abdulrab]

nope...if the points are going in a curve path, then u have to draw a curve ofcourse

thanku

 

[larina]

thanku

ur welcome

 

[angelicsuccubus]

http://www.xtremepapers.com/papers/... AS Level/Chemistry (9701)/9701_s10_qp_51.pdf
how do you calculate the volume in 1 a?

 

[BazD]

Let's

http://www.xtremepapers.com/papers/... AS Level/Chemistry (9701)/9701_s10_qp_51.pdf
how do you calculate the volume in 1 a?

assume you take your x value as 20cm3, now I believe you would know that to neutralize 20 cm3 of 3moldm-3 NaOH you will need 20cm3 of 3moldm-3 h2so4.
Now calculate no of moles in 20 cm3 of 3moldm-3 H2SO4 , put this value of moles in this eqn 2=(no.of moles) / (volume needed)
The above eqn basically is trying to calculate volume needed when u use 2 moldm-3 conc of h2so4.
We calculated value of moles to know how many are needed to neutralize our choice of volume of solution.
answer then is 30 cm3

 

[angelicsuccubus]

Let's
assume you take your x value as 20cm3, now I believe you would know that to neutralize 20 cm3 of 3moldm-3 NaOH you will need 20cm3 of 3moldm-3 h2so4.
Now calculate no of moles in 20 cm3 of 3moldm-3 H2SO4 , put this value of moles in this eqn 2=(no.of moles) / (volume needed)
The above eqn basically is trying to calculate volume needed when u use 2 moldm-3 conc of h2so4.
We calculated value of moles to know how many are needed to neutralize our choice of volume of solution.
answer then is 30 cm3

ehh... at the risk of soundin like a complete idiot, I don't think I got it.

 

[angelicsuccubus]

okay, experiments that have showed up so far (I think I'm doing this more for myself than anyone else, considering you're all asleep)

• Hydrochloric acid and magnesium ribbon (investigating rate of reaction of gas produced)
• Determining the formula of the chloride
• Determining the enthalpy change of combustion
• Determining the relative formula mass (decomposing basic carbonate)
• Thermal decomposition of caesium nitrate
• Determine the transition temperature (solubility question)
• Acid-base neutralisation

• Confirming the formula of magnesium oxide is MgO
  
  okay Im tired .. but from what I can see, should have studied A2 syllabus for this -_- .. a lota perioidic trends..
  
  
  
  
  
  

 

[zenyatales]

how do you calculate the volume in 1 a?

For 2 mol of NaOH --- 1 mol of H2SO4 has been required (according to the balanced equation given)
For 1 mol of NaOH --- we'd need 0.5 mol of H2SO4.

Since we have the volume and concentration of NaOH, we can find the no. of moles of NaOH in that solution.
n = v * c
= (let) 0.050 * 3
=0.15 moles

Then we 'd need half the no. of moles of H2SO4,i.e 0.075 moles, and we are given the conc. so that makes :
v = n / c
= o.o75 / 2
= 37.5 cm3 of H2SO4

 

[shamil]

some1 explain to me dependent and independent variables ??

independant variable is what we change in the experiment and is on the X axis. The dependant variable is what is affected when we change the independant variable

 

[zenyatales]

http://www.xtremepapers.com/papers/... AS Level/Chemistry (9701)/9701_w10_qp_53.pdf

Q. no. 1 c :- How to ensure that none of the oxygen is lost ?
Generally, how do you prepare 'divided flasks' ? To prevent the loss of gas produced in the equation ?

http://www.xtremepapers.com/papers/... AS Level/Chemistry (9701)/9701_s07_er.pdf
1d vii.

 

[Romeo10]

How can I calculate the slop of the graphhhh ?? Plz answer my exam is after 12 hours ??

 

[hassam]

thats easy.....delta y/delta x
cn smone tell me waht moles to divide by when calclating enthaloy change of neutralization

 

[zenyatales]

for enthalpy change of neutralisation, divide by the no. of moles of that-which-is-not-in-excess ?

 

[smzimran]

thats easy.....delta y/delta x
cn smone tell me waht moles to divide by when calclating enthaloy change of neutralization

Divide by moles of limiting reactant

 

[miss irfan]

How can I calculate the slop of the graphhhh ?? Plz answer my exam is after 12 hours ??

the limiting ones. if acid is limiting then divide by acid moles.